IT. Expert System.

Android Reference

Activity


android.app

Class Activity

  • All Implemented Interfaces:
    ComponentCallbacks, ComponentCallbacks2, KeyEvent.Callback, LayoutInflater.Factory, LayoutInflater.Factory2, View.OnCreateContextMenuListener, Window.Callback
    Direct Known Subclasses:
    AccessibilityInjectorTestActivity, AccountAuthenticatorActivity, ActivityGroup, AddColumn, AdjacentListsWithAdjacentISVsInside, AdjacentVerticalRectLists, AliasActivity, AutoCompleteTextViewSimple, BaselineAlignmentCenterGravity, BaselineAlignmentZeroWidthAndWeight, BaselineButtons, BasicAnimatorActivity, BigCache, BitmapDrawable, BrightnessLimit, CameraEffectsRecordingSample, CellSpan, ChooseAccountActivity, ChooseAccountTypeActivity, ChooseTypeAndAccountActivity, ClearTop, DescendantFocusability, Disabled, DrawableBgMinSize, ExpandableListActivity, FillInWrap, FixedWidth, FocusAfterRemoval, FragmentActivity, FrameLayoutGravity, FrameLayoutMargin, GlobalFocusChange, GoneParentFocusedChild, GrantCredentialsPermissionActivity, GridInHorizontal, GridInVertical, GridPadding, GridScenario, GridScrollListener, GridThrasher, HorizontalFocusSearch, HorizontalGravity, HorizontalOrientationVerticalAlignment, Include, InterrogationActivity, LaunchpadActivity, LinearLayoutEditTexts, LinearLayoutGrid, ListActivity, ListDividers, ListInHorizontal, ListInVertical, ListOfEditTexts, ListOfInternalSelectionViews, ListRecyclerProfiling, ListScenario, ListViewHeight, LLEditTextThenButton, LLOfButtons1, LLOfTwoFocusableInTouchMode, Longpress, MenuScenario, Merge, MutateDrawable, NativeActivity, PopupWindowVisibility, PreDrawListener, RadioGroupActivity, RemoteViewsActivity, RequestFocus, RequestRectangleVisible, RequestRectangleVisibleWithInternalScroll, RunQueue, ScrollViewButtonsAndLabels, ScrollViewScenario, SearchableActivity, StubbedView, SubActivityScreen, SyncActivityTooManyDeletes, TestedActivity, TestedScreen, TranslucentFancyActivity, VerticalFocusSearch, VerticalGravity, ViewAttachTestActivity, ViewGroupChildren, Visibility, VisibilityCallback, Weight, Weight, WeightSum, ZeroSized


    public class Activity
    extends ContextThemeWrapper
    implements LayoutInflater.Factory2, Window.Callback, KeyEvent.Callback, View.OnCreateContextMenuListener, ComponentCallbacks2
    An activity is a single, focused thing that the user can do. Almost all activities interact with the user, so the Activity class takes care of creating a window for you in which you can place your UI with setContentView(int). While activities are often presented to the user as full-screen windows, they can also be used in other ways: as floating windows (via a theme with android.R.attr#windowIsFloating set) or embedded inside of another activity (using ActivityGroup). There are two methods almost all subclasses of Activity will implement:
    • onCreate(android.os.Bundle) is where you initialize your activity. Most importantly, here you will usually call setContentView(int) with a layout resource defining your UI, and using findViewById(int) to retrieve the widgets in that UI that you need to interact with programmatically.
    • onPause() is where you deal with the user leaving your activity. Most importantly, any changes made by the user should at this point be committed (usually to the ContentProvider holding the data).

    To be of use with Context.startActivity(), all activity classes must have a corresponding <activity> declaration in their package's AndroidManifest.xml.

    Topics covered here:

    1. Fragments
    2. Activity Lifecycle
    3. Configuration Changes
    4. Starting Activities and Getting Results
    5. Saving Persistent State
    6. Permissions
    7. Process Lifecycle

    Developer Guides

    The Activity class is an important part of an application's overall lifecycle, and the way activities are launched and put together is a fundamental part of the platform's application model. For a detailed perspective on the structure of an Android application and how activities behave, please read the Application Fundamentals and Tasks and Back Stack developer guides.

    You can also find a detailed discussion about how to create activities in the Activities developer guide.

    Fragments

    Starting with Build.VERSION_CODES.HONEYCOMB, Activity implementations can make use of the Fragment class to better modularize their code, build more sophisticated user interfaces for larger screens, and help scale their application between small and large screens.

    Activity Lifecycle

    Activities in the system are managed as an activity stack. When a new activity is started, it is placed on the top of the stack and becomes the running activity -- the previous activity always remains below it in the stack, and will not come to the foreground again until the new activity exits.

    An activity has essentially four states:

    • If an activity in the foreground of the screen (at the top of the stack), it is active or running.
    • If an activity has lost focus but is still visible (that is, a new non-full-sized or transparent activity has focus on top of your activity), it is paused. A paused activity is completely alive (it maintains all state and member information and remains attached to the window manager), but can be killed by the system in extreme low memory situations.
    • If an activity is completely obscured by another activity, it is stopped. It still retains all state and member information, however, it is no longer visible to the user so its window is hidden and it will often be killed by the system when memory is needed elsewhere.
    • If an activity is paused or stopped, the system can drop the activity from memory by either asking it to finish, or simply killing its process. When it is displayed again to the user, it must be completely restarted and restored to its previous state.

    The following diagram shows the important state paths of an Activity. The square rectangles represent callback methods you can implement to perform operations when the Activity moves between states. The colored ovals are major states the Activity can be in.

    state diagram for an android activity lifecycle.

    There are three key loops you may be interested in monitoring within your activity:

    • The entire lifetime of an activity happens between the first call to onCreate(android.os.Bundle) through to a single final call to onDestroy(). An activity will do all setup of "global" state in onCreate(), and release all remaining resources in onDestroy(). For example, if it has a thread running in the background to download data from the network, it may create that thread in onCreate() and then stop the thread in onDestroy().
    • The visible lifetime of an activity happens between a call to onStart() until a corresponding call to onStop(). During this time the user can see the activity on-screen, though it may not be in the foreground and interacting with the user. Between these two methods you can maintain resources that are needed to show the activity to the user. For example, you can register a BroadcastReceiver in onStart() to monitor for changes that impact your UI, and unregister it in onStop() when the user no longer sees what you are displaying. The onStart() and onStop() methods can be called multiple times, as the activity becomes visible and hidden to the user.
    • The foreground lifetime of an activity happens between a call to onResume() until a corresponding call to onPause(). During this time the activity is in front of all other activities and interacting with the user. An activity can frequently go between the resumed and paused states -- for example when the device goes to sleep, when an activity result is delivered, when a new intent is delivered -- so the code in these methods should be fairly lightweight.

    The entire lifecycle of an activity is defined by the following Activity methods. All of these are hooks that you can override to do appropriate work when the activity changes state. All activities will implement onCreate(android.os.Bundle) to do their initial setup; many will also implement onPause() to commit changes to data and otherwise prepare to stop interacting with the user. You should always call up to your superclass when implementing these methods.

     public class Activity extends ApplicationContext {
         protected void onCreate(Bundle savedInstanceState);
    
         protected void onStart();
         
         protected void onRestart();
    
         protected void onResume();
    
         protected void onPause();
    
         protected void onStop();
    
         protected void onDestroy();
     }
     

    In general the movement through an activity's lifecycle looks like this:

    Method Description Killable? Next
    onCreate() Called when the activity is first created. This is where you should do all of your normal static set up: create views, bind data to lists, etc. This method also provides you with a Bundle containing the activity's previously frozen state, if there was one.

    Always followed by onStart().

    No onStart()
    onRestart() Called after your activity has been stopped, prior to it being started again.

    Always followed by onStart()

    No onStart()
    onStart() Called when the activity is becoming visible to the user.

    Followed by onResume() if the activity comes to the foreground, or onStop() if it becomes hidden.

    No onResume() or onStop()
    onResume() Called when the activity will start interacting with the user. At this point your activity is at the top of the activity stack, with user input going to it.

    Always followed by onPause().

    No onPause()
    onPause() Called when the system is about to start resuming a previous activity. This is typically used to commit unsaved changes to persistent data, stop animations and other things that may be consuming CPU, etc. Implementations of this method must be very quick because the next activity will not be resumed until this method returns.

    Followed by either onResume() if the activity returns back to the front, or onStop() if it becomes invisible to the user.

    Pre-Build.VERSION_CODES.HONEYCOMB onResume() or
    onStop()
    onStop() Called when the activity is no longer visible to the user, because another activity has been resumed and is covering this one. This may happen either because a new activity is being started, an existing one is being brought in front of this one, or this one is being destroyed.

    Followed by either onRestart() if this activity is coming back to interact with the user, or onDestroy() if this activity is going away.

    Yes onRestart() or
    onDestroy()
    onDestroy() The final call you receive before your activity is destroyed. This can happen either because the activity is finishing (someone called finish() on it, or because the system is temporarily destroying this instance of the activity to save space. You can distinguish between these two scenarios with the isFinishing() method. Yes nothing

    Note the "Killable" column in the above table -- for those methods that are marked as being killable, after that method returns the process hosting the activity may killed by the system at any time without another line of its code being executed. Because of this, you should use the onPause() method to write any persistent data (such as user edits) to storage. In addition, the method onSaveInstanceState(Bundle) is called before placing the activity in such a background state, allowing you to save away any dynamic instance state in your activity into the given Bundle, to be later received in onCreate(android.os.Bundle) if the activity needs to be re-created. See the Process Lifecycle section for more information on how the lifecycle of a process is tied to the activities it is hosting. Note that it is important to save persistent data in onPause() instead of onSaveInstanceState(android.os.Bundle) because the latter is not part of the lifecycle callbacks, so will not be called in every situation as described in its documentation.

    Be aware that these semantics will change slightly between applications targeting platforms starting with Build.VERSION_CODES.HONEYCOMB vs. those targeting prior platforms. Starting with Honeycomb, an application is not in the killable state until its onStop() has returned. This impacts when onSaveInstanceState(Bundle) may be called (it may be safely called after onPause() and allows and application to safely wait until onStop() to save persistent state.

    For those methods that are not marked as being killable, the activity's process will not be killed by the system starting from the time the method is called and continuing after it returns. Thus an activity is in the killable state, for example, between after onPause() to the start of onResume().

    Configuration Changes

    If the configuration of the device (as defined by the Resources.Configuration class) changes, then anything displaying a user interface will need to update to match that configuration. Because Activity is the primary mechanism for interacting with the user, it includes special support for handling configuration changes.

    Unless you specify otherwise, a configuration change (such as a change in screen orientation, language, input devices, etc) will cause your current activity to be destroyed, going through the normal activity lifecycle process of onPause(), onStop(), and onDestroy() as appropriate. If the activity had been in the foreground or visible to the user, once onDestroy() is called in that instance then a new instance of the activity will be created, with whatever savedInstanceState the previous instance had generated from onSaveInstanceState(android.os.Bundle).

    This is done because any application resource, including layout files, can change based on any configuration value. Thus the only safe way to handle a configuration change is to re-retrieve all resources, including layouts, drawables, and strings. Because activities must already know how to save their state and re-create themselves from that state, this is a convenient way to have an activity restart itself with a new configuration.

    In some special cases, you may want to bypass restarting of your activity based on one or more types of configuration changes. This is done with the android:configChanges attribute in its manifest. For any types of configuration changes you say that you handle there, you will receive a call to your current activity's onConfigurationChanged(android.content.res.Configuration) method instead of being restarted. If a configuration change involves any that you do not handle, however, the activity will still be restarted and onConfigurationChanged(android.content.res.Configuration) will not be called.

    Starting Activities and Getting Results

    The startActivity(android.content.Intent) method is used to start a new activity, which will be placed at the top of the activity stack. It takes a single argument, an Intent, which describes the activity to be executed.

    Sometimes you want to get a result back from an activity when it ends. For example, you may start an activity that lets the user pick a person in a list of contacts; when it ends, it returns the person that was selected. To do this, you call the startActivityForResult(Intent, int) version with a second integer parameter identifying the call. The result will come back through your onActivityResult(int, int, android.content.Intent) method.

    When an activity exits, it can call setResult(int) to return data back to its parent. It must always supply a result code, which can be the standard results RESULT_CANCELED, RESULT_OK, or any custom values starting at RESULT_FIRST_USER. In addition, it can optionally return back an Intent containing any additional data it wants. All of this information appears back on the parent's Activity.onActivityResult(), along with the integer identifier it originally supplied.

    If a child activity fails for any reason (such as crashing), the parent activity will receive a result with the code RESULT_CANCELED.

     public class MyActivity extends Activity {
         ...
    
         static final int PICK_CONTACT_REQUEST = 0;
    
         protected boolean onKeyDown(int keyCode, KeyEvent event) {
             if (keyCode == KeyEvent.KEYCODE_DPAD_CENTER) {
                 // When the user center presses, let them pick a contact.
                 startActivityForResult(
                     new Intent(Intent.ACTION_PICK,
                     new Uri("content://contacts")),
                     PICK_CONTACT_REQUEST);
                return true;
             }
             return false;
         }
    
         protected void onActivityResult(int requestCode, int resultCode,
                 Intent data) {
             if (requestCode == PICK_CONTACT_REQUEST) {
                 if (resultCode == RESULT_OK) {
                     // A contact was picked.  Here we will just display it
                     // to the user.
                     startActivity(new Intent(Intent.ACTION_VIEW, data));
                 }
             }
         }
     }
     

    Saving Persistent State

    There are generally two kinds of persistent state than an activity will deal with: shared document-like data (typically stored in a SQLite database using a content provider) and internal state such as user preferences.

    For content provider data, we suggest that activities use a "edit in place" user model. That is, any edits a user makes are effectively made immediately without requiring an additional confirmation step. Supporting this model is generally a simple matter of following two rules:

    • When creating a new document, the backing database entry or file for it is created immediately. For example, if the user chooses to write a new e-mail, a new entry for that e-mail is created as soon as they start entering data, so that if they go to any other activity after that point this e-mail will now appear in the list of drafts.

    • When an activity's onPause() method is called, it should commit to the backing content provider or file any changes the user has made. This ensures that those changes will be seen by any other activity that is about to run. You will probably want to commit your data even more aggressively at key times during your activity's lifecycle: for example before starting a new activity, before finishing your own activity, when the user switches between input fields, etc.

    This model is designed to prevent data loss when a user is navigating between activities, and allows the system to safely kill an activity (because system resources are needed somewhere else) at any time after it has been paused. Note this implies that the user pressing BACK from your activity does not mean "cancel" -- it means to leave the activity with its current contents saved away. Canceling edits in an activity must be provided through some other mechanism, such as an explicit "revert" or "undo" option.

    See the content package for more information about content providers. These are a key aspect of how different activities invoke and propagate data between themselves.

    The Activity class also provides an API for managing internal persistent state associated with an activity. This can be used, for example, to remember the user's preferred initial display in a calendar (day view or week view) or the user's default home page in a web browser.

    Activity persistent state is managed with the method getPreferences(int), allowing you to retrieve and modify a set of name/value pairs associated with the activity. To use preferences that are shared across multiple application components (activities, receivers, services, providers), you can use the underlying Context.getSharedPreferences() method to retrieve a preferences object stored under a specific name. (Note that it is not possible to share settings data across application packages -- for that you will need a content provider.)

    Here is an excerpt from a calendar activity that stores the user's preferred view mode in its persistent settings:

     public class CalendarActivity extends Activity {
         ...
    
         static final int DAY_VIEW_MODE = 0;
         static final int WEEK_VIEW_MODE = 1;
    
         private SharedPreferences mPrefs;
         private int mCurViewMode;
    
         protected void onCreate(Bundle savedInstanceState) {
             super.onCreate(savedInstanceState);
    
             SharedPreferences mPrefs = getSharedPreferences();
             mCurViewMode = mPrefs.getInt("view_mode", DAY_VIEW_MODE);
         }
    
         protected void onPause() {
             super.onPause();
     
             SharedPreferences.Editor ed = mPrefs.edit();
             ed.putInt("view_mode", mCurViewMode);
             ed.commit();
         }
     }
     

    Permissions

    The ability to start a particular Activity can be enforced when it is declared in its manifest's <activity> tag. By doing so, other applications will need to declare a corresponding <uses-permission> element in their own manifest to be able to start that activity.

    When starting an Activity you can set Intent.FLAG_GRANT_READ_URI_PERMISSION and/or Intent.FLAG_GRANT_WRITE_URI_PERMISSION on the Intent. This will grant the Activity access to the specific URIs in the Intent. Access will remain until the Activity has finished (it will remain across the hosting process being killed and other temporary destruction). As of Build.VERSION_CODES.GINGERBREAD, if the Activity was already created and a new Intent is being delivered to onNewIntent(Intent), any newly granted URI permissions will be added to the existing ones it holds.

    See the Security and Permissions document for more information on permissions and security in general.

    Process Lifecycle

    The Android system attempts to keep application process around for as long as possible, but eventually will need to remove old processes when memory runs low. As described in Activity Lifecycle, the decision about which process to remove is intimately tied to the state of the user's interaction with it. In general, there are four states a process can be in based on the activities running in it, listed here in order of importance. The system will kill less important processes (the last ones) before it resorts to killing more important processes (the first ones).

    1. The foreground activity (the activity at the top of the screen that the user is currently interacting with) is considered the most important. Its process will only be killed as a last resort, if it uses more memory than is available on the device. Generally at this point the device has reached a memory paging state, so this is required in order to keep the user interface responsive.

    2. A visible activity (an activity that is visible to the user but not in the foreground, such as one sitting behind a foreground dialog) is considered extremely important and will not be killed unless that is required to keep the foreground activity running.

    3. A background activity (an activity that is not visible to the user and has been paused) is no longer critical, so the system may safely kill its process to reclaim memory for other foreground or visible processes. If its process needs to be killed, when the user navigates back to the activity (making it visible on the screen again), its onCreate(android.os.Bundle) method will be called with the savedInstanceState it had previously supplied in onSaveInstanceState(android.os.Bundle) so that it can restart itself in the same state as the user last left it.

    4. An empty process is one hosting no activities or other application components (such as Service or BroadcastReceiver classes). These are killed very quickly by the system as memory becomes low. For this reason, any background operation you do outside of an activity must be executed in the context of an activity BroadcastReceiver or Service to ensure that the system knows it needs to keep your process around.

    Sometimes an Activity may need to do a long-running operation that exists independently of the activity lifecycle itself. An example may be a camera application that allows you to upload a picture to a web site. The upload may take a long time, and the application should allow the user to leave the application will it is executing. To accomplish this, your Activity should start a Service in which the upload takes place. This allows the system to properly prioritize your process (considering it to be more important than other non-visible applications) for the duration of the upload, independent of whether the original activity is paused, stopped, or finished.

    • Constructor Detail

      • Activity

        public Activity()
    • Method Detail

      • getIntent

        public Intent getIntent()
        Return the intent that started this activity.
      • getApplication

        public final Application getApplication()
        Return the application that owns this activity.
      • isChild

        public final boolean isChild()
        Is this activity embedded inside of another activity?
      • getParent

        public final Activity getParent()
        Return the parent activity if this view is an embedded child.
      • getWindowManager

        public WindowManager getWindowManager()
        Retrieve the window manager for showing custom windows.
      • getWindow

        public Window getWindow()
        Retrieve the current Window for the activity. This can be used to directly access parts of the Window API that are not available through Activity/Screen.
        Returns:
        Window The current window, or null if the activity is not visual.
      • getLoaderManager

        public LoaderManager getLoaderManager()
        Return the LoaderManager for this fragment, creating it if needed.
      • onPostCreate

        protected void onPostCreate(Bundle savedInstanceState)
        Called when activity start-up is complete (after onStart() and onRestoreInstanceState(android.os.Bundle) have been called). Applications will generally not implement this method; it is intended for system classes to do final initialization after application code has run.

        Derived classes must call through to the super class's implementation of this method. If they do not, an exception will be thrown.

        Parameters:
        savedInstanceState - If the activity is being re-initialized after previously being shut down then this Bundle contains the data it most recently supplied in onSaveInstanceState(android.os.Bundle). Note: Otherwise it is null.
        See Also:
        onCreate(android.os.Bundle)
      • onPostResume

        protected void onPostResume()
        Called when activity resume is complete (after onResume() has been called). Applications will generally not implement this method; it is intended for system classes to do final setup after application resume code has run.

        Derived classes must call through to the super class's implementation of this method. If they do not, an exception will be thrown.

        See Also:
        onResume()
      • onSaveInstanceState

        protected void onSaveInstanceState(Bundle outState)
        Called to retrieve per-instance state from an activity before being killed so that the state can be restored in onCreate(android.os.Bundle) or onRestoreInstanceState(android.os.Bundle) (the Bundle populated by this method will be passed to both).

        This method is called before an activity may be killed so that when it comes back some time in the future it can restore its state. For example, if activity B is launched in front of activity A, and at some point activity A is killed to reclaim resources, activity A will have a chance to save the current state of its user interface via this method so that when the user returns to activity A, the state of the user interface can be restored via onCreate(android.os.Bundle) or onRestoreInstanceState(android.os.Bundle).

        Do not confuse this method with activity lifecycle callbacks such as onPause(), which is always called when an activity is being placed in the background or on its way to destruction, or onStop() which is called before destruction. One example of when onPause() and onStop() is called and not this method is when a user navigates back from activity B to activity A: there is no need to call onSaveInstanceState(android.os.Bundle) on B because that particular instance will never be restored, so the system avoids calling it. An example when onPause() is called and not onSaveInstanceState(android.os.Bundle) is when activity B is launched in front of activity A: the system may avoid calling onSaveInstanceState(android.os.Bundle) on activity A if it isn't killed during the lifetime of B since the state of the user interface of A will stay intact.

        The default implementation takes care of most of the UI per-instance state for you by calling View.onSaveInstanceState() on each view in the hierarchy that has an id, and by saving the id of the currently focused view (all of which is restored by the default implementation of onRestoreInstanceState(android.os.Bundle)). If you override this method to save additional information not captured by each individual view, you will likely want to call through to the default implementation, otherwise be prepared to save all of the state of each view yourself.

        If called, this method will occur before onStop(). There are no guarantees about whether it will occur before or after onPause().

        Parameters:
        outState - Bundle in which to place your saved state.
        See Also:
        onCreate(android.os.Bundle), onRestoreInstanceState(android.os.Bundle), onPause()
      • onPause

        protected void onPause()
        Called as part of the activity lifecycle when an activity is going into the background, but has not (yet) been killed. The counterpart to onResume().

        When activity B is launched in front of activity A, this callback will be invoked on A. B will not be created until A's onPause() returns, so be sure to not do anything lengthy here.

        This callback is mostly used for saving any persistent state the activity is editing, to present a "edit in place" model to the user and making sure nothing is lost if there are not enough resources to start the new activity without first killing this one. This is also a good place to do things like stop animations and other things that consume a noticeable amount of CPU in order to make the switch to the next activity as fast as possible, or to close resources that are exclusive access such as the camera.

        In situations where the system needs more memory it may kill paused processes to reclaim resources. Because of this, you should be sure that all of your state is saved by the time you return from this function. In general onSaveInstanceState(android.os.Bundle) is used to save per-instance state in the activity and this method is used to store global persistent data (in content providers, files, etc.)

        After receiving this call you will usually receive a following call to onStop() (after the next activity has been resumed and displayed), however in some cases there will be a direct call back to onResume() without going through the stopped state.

        Derived classes must call through to the super class's implementation of this method. If they do not, an exception will be thrown.

        See Also:
        onResume(), onSaveInstanceState(android.os.Bundle), onStop()
      • onUserLeaveHint

        protected void onUserLeaveHint()
        Called as part of the activity lifecycle when an activity is about to go into the background as the result of user choice. For example, when the user presses the Home key, onUserLeaveHint() will be called, but when an incoming phone call causes the in-call Activity to be automatically brought to the foreground, onUserLeaveHint() will not be called on the activity being interrupted. In cases when it is invoked, this method is called right before the activity's onPause() callback.

        This callback and onUserInteraction() are intended to help activities manage status bar notifications intelligently; specifically, for helping activities determine the proper time to cancel a notfication.

        See Also:
        onUserInteraction()
      • onCreateThumbnail

        public boolean onCreateThumbnail(Bitmap outBitmap,
                                Canvas canvas)
        Generate a new thumbnail for this activity. This method is called before pausing the activity, and should draw into outBitmap the imagery for the desired thumbnail in the dimensions of that bitmap. It can use the given canvas, which is configured to draw into the bitmap, for rendering if desired.

        The default implementation returns fails and does not draw a thumbnail; this will result in the platform creating its own thumbnail if needed.

        Parameters:
        outBitmap - The bitmap to contain the thumbnail.
        canvas - Can be used to render into the bitmap.
        Returns:
        Return true if you have drawn into the bitmap; otherwise after you return it will be filled with a default thumbnail.
        See Also:
        onCreateDescription(), onSaveInstanceState(android.os.Bundle), onPause()
      • onCreateDescription

        public CharSequence onCreateDescription()
        Generate a new description for this activity. This method is called before pausing the activity and can, if desired, return some textual description of its current state to be displayed to the user.

        The default implementation returns null, which will cause you to inherit the description from the previous activity. If all activities return null, generally the label of the top activity will be used as the description.

        Returns:
        A description of what the user is doing. It should be short and sweet (only a few words).
        See Also:
        onCreateThumbnail(android.graphics.Bitmap, android.graphics.Canvas), onSaveInstanceState(android.os.Bundle), onPause()
      • onStop

        protected void onStop()
        Called when you are no longer visible to the user. You will next receive either onRestart(), onDestroy(), or nothing, depending on later user activity.

        Note that this method may never be called, in low memory situations where the system does not have enough memory to keep your activity's process running after its onPause() method is called.

        Derived classes must call through to the super class's implementation of this method. If they do not, an exception will be thrown.

        See Also:
        onRestart(), onResume(), onSaveInstanceState(android.os.Bundle), onDestroy()
      • onDestroy

        protected void onDestroy()
        Perform any final cleanup before an activity is destroyed. This can happen either because the activity is finishing (someone called finish() on it, or because the system is temporarily destroying this instance of the activity to save space. You can distinguish between these two scenarios with the isFinishing() method.

        Note: do not count on this method being called as a place for saving data! For example, if an activity is editing data in a content provider, those edits should be committed in either onPause() or onSaveInstanceState(android.os.Bundle), not here. This method is usually implemented to free resources like threads that are associated with an activity, so that a destroyed activity does not leave such things around while the rest of its application is still running. There are situations where the system will simply kill the activity's hosting process without calling this method (or any others) in it, so it should not be used to do things that are intended to remain around after the process goes away.

        Derived classes must call through to the super class's implementation of this method. If they do not, an exception will be thrown.

        See Also:
        onPause(), onStop(), finish(), isFinishing()
      • onConfigurationChanged

        public void onConfigurationChanged(Configuration newConfig)
        Called by the system when the device configuration changes while your activity is running. Note that this will only be called if you have selected configurations you would like to handle with the android.R.attr#configChanges attribute in your manifest. If any configuration change occurs that is not selected to be reported by that attribute, then instead of reporting it the system will stop and restart the activity (to have it launched with the new configuration).

        At the time that this function has been called, your Resources object will have been updated to return resource values matching the new configuration.

        Specified by:
        onConfigurationChanged in interface ComponentCallbacks
        Parameters:
        newConfig - The new device configuration.
      • getChangingConfigurations

        public int getChangingConfigurations()
        If this activity is being destroyed because it can not handle a configuration parameter being changed (and thus its onConfigurationChanged(Configuration) method is not being called), then you can use this method to discover the set of changes that have occurred while in the process of being destroyed. Note that there is no guarantee that these will be accurate (other changes could have happened at any time), so you should only use this as an optimization hint.
        Returns:
        Returns a bit field of the configuration parameters that are changing, as defined by the Configuration class.
      • getLastNonConfigurationInstance

        @Deprecated
        public Object getLastNonConfigurationInstance()
        Deprecated. Use the new Fragment API Fragment.setRetainInstance(boolean) instead; this is also available on older platforms through the Android compatibility package.
        Retrieve the non-configuration instance data that was previously returned by onRetainNonConfigurationInstance(). This will be available from the initial onCreate(android.os.Bundle) and onStart() calls to the new instance, allowing you to extract any useful dynamic state from the previous instance.

        Note that the data you retrieve here should only be used as an optimization for handling configuration changes. You should always be able to handle getting a null pointer back, and an activity must still be able to restore itself to its previous state (through the normal onSaveInstanceState(Bundle) mechanism) even if this function returns null.

        Returns:
        Returns the object previously returned by onRetainNonConfigurationInstance().
      • onRetainNonConfigurationInstance

        public Object onRetainNonConfigurationInstance()
        Deprecated. Use the new Fragment API Fragment.setRetainInstance(boolean) instead; this is also available on older platforms through the Android compatibility package.
        Called by the system, as part of destroying an activity due to a configuration change, when it is known that a new instance will immediately be created for the new configuration. You can return any object you like here, including the activity instance itself, which can later be retrieved by calling getLastNonConfigurationInstance() in the new activity instance. If you are targeting Build.VERSION_CODES.HONEYCOMB or later, consider instead using a Fragment with Fragment.setRetainInstance(boolean.

        This function is called purely as an optimization, and you must not rely on it being called. When it is called, a number of guarantees will be made to help optimize configuration switching:

        • The function will be called between onStop() and onDestroy().
        • A new instance of the activity will always be immediately created after this one's onDestroy() is called. In particular, no messages will be dispatched during this time (when the returned object does not have an activity to be associated with).
        • The object you return here will always be available from the getLastNonConfigurationInstance() method of the following activity instance as described there.

        These guarantees are designed so that an activity can use this API to propagate extensive state from the old to new activity instance, from loaded bitmaps, to network connections, to evenly actively running threads. Note that you should not propagate any data that may change based on the configuration, including any data loaded from resources such as strings, layouts, or drawables.

        The guarantee of no message handling during the switch to the next activity simplifies use with active objects. For example if your retained state is an AsyncTask you are guaranteed that its call back functions (like AsyncTask.onPostExecute(Result)) will not be called from the call here until you execute the next instance's onCreate(Bundle). (Note however that there is of course no such guarantee for AsyncTask.doInBackground(Params...) since that is running in a separate thread.)

        Returns:
        Return any Object holding the desired state to propagate to the next activity instance.
      • onLowMemory

        public void onLowMemory()
        Description copied from interface: ComponentCallbacks
        This is called when the overall system is running low on memory, and would like actively running process to try to tighten their belt. While the exact point at which this will be called is not defined, generally it will happen around the time all background process have been killed, that is before reaching the point of killing processes hosting service and foreground UI that we would like to avoid killing.

        Applications that want to be nice can implement this method to release any caches or other unnecessary resources they may be holding on to. The system will perform a gc for you after returning from this method.

        Specified by:
        onLowMemory in interface ComponentCallbacks
      • getFragmentManager

        public FragmentManager getFragmentManager()
        Return the FragmentManager for interacting with fragments associated with this activity.
      • findViewById

        public View findViewById(int id)
        Finds a view that was identified by the id attribute from the XML that was processed in onCreate(android.os.Bundle).
        Returns:
        The view if found or null otherwise.
      • getActionBar

        public ActionBar getActionBar()
        Retrieve a reference to this activity's ActionBar.
        Returns:
        The Activity's ActionBar, or null if it does not have one.
      • setContentView

        public void setContentView(View view,
                          ViewGroup.LayoutParams params)
        Set the activity content to an explicit view. This view is placed directly into the activity's view hierarchy. It can itself be a complex view hierarchy.
        Parameters:
        view - The desired content to display.
        params - Layout parameters for the view.
        See Also:
        setContentView(android.view.View), setContentView(int)
      • addContentView

        public void addContentView(View view,
                          ViewGroup.LayoutParams params)
        Add an additional content view to the activity. Added after any existing ones in the activity -- existing views are NOT removed.
        Parameters:
        view - The desired content to display.
        params - Layout parameters for the view.
      • setFinishOnTouchOutside

        public void setFinishOnTouchOutside(boolean finish)
        Sets whether this activity is finished when touched outside its window's bounds.
      • onKeyDown

        public boolean onKeyDown(int keyCode,
                        KeyEvent event)
        Called when a key was pressed down and not handled by any of the views inside of the activity. So, for example, key presses while the cursor is inside a TextView will not trigger the event (unless it is a navigation to another object) because TextView handles its own key presses.

        If the focused view didn't want this event, this method is called.

        The default implementation takes care of KeyEvent.KEYCODE_BACK by calling onBackPressed(), though the behavior varies based on the application compatibility mode: for Build.VERSION_CODES.ECLAIR or later applications, it will set up the dispatch to call onKeyUp(int, android.view.KeyEvent) where the action will be performed; for earlier applications, it will perform the action immediately in on-down, as those versions of the platform behaved.

        Other additional default key handling may be performed if configured with setDefaultKeyMode(int).

        Specified by:
        onKeyDown in interface KeyEvent.Callback
        Parameters:
        keyCode - The value in event.getKeyCode().
        event - Description of the key event.
        Returns:
        Return true to prevent this event from being propagated further, or false to indicate that you have not handled this event and it should continue to be propagated.
        See Also:
        onKeyUp(int, android.view.KeyEvent), KeyEvent
      • onKeyLongPress

        public boolean onKeyLongPress(int keyCode,
                             KeyEvent event)
        Default implementation of KeyEvent.Callback.onKeyLongPress(): always returns false (doesn't handle the event).
        Specified by:
        onKeyLongPress in interface KeyEvent.Callback
        Parameters:
        keyCode - The value in event.getKeyCode().
        event - Description of the key event.
        Returns:
        If you handled the event, return true. If you want to allow the event to be handled by the next receiver, return false.
      • onKeyUp

        public boolean onKeyUp(int keyCode,
                      KeyEvent event)
        Called when a key was released and not handled by any of the views inside of the activity. So, for example, key presses while the cursor is inside a TextView will not trigger the event (unless it is a navigation to another object) because TextView handles its own key presses.

        The default implementation handles KEYCODE_BACK to stop the activity and go back.

        Specified by:
        onKeyUp in interface KeyEvent.Callback
        Parameters:
        keyCode - The value in event.getKeyCode().
        event - Description of the key event.
        Returns:
        Return true to prevent this event from being propagated further, or false to indicate that you have not handled this event and it should continue to be propagated.
        See Also:
        onKeyDown(int, android.view.KeyEvent), KeyEvent
      • onKeyMultiple

        public boolean onKeyMultiple(int keyCode,
                            int repeatCount,
                            KeyEvent event)
        Default implementation of KeyEvent.Callback.onKeyMultiple(): always returns false (doesn't handle the event).
        Specified by:
        onKeyMultiple in interface KeyEvent.Callback
        Parameters:
        keyCode - The value in event.getKeyCode().
        repeatCount - Number of pairs as returned by event.getRepeatCount().
        event - Description of the key event.
        Returns:
        If you handled the event, return true. If you want to allow the event to be handled by the next receiver, return false.
      • onBackPressed

        public void onBackPressed()
        Called when the activity has detected the user's press of the back key. The default implementation simply finishes the current activity, but you can override this to do whatever you want.
      • onKeyShortcut

        public boolean onKeyShortcut(int keyCode,
                            KeyEvent event)
        Called when a key shortcut event is not handled by any of the views in the Activity. Override this method to implement global key shortcuts for the Activity. Key shortcuts can also be implemented by setting the shortcut property of menu items.
        Parameters:
        keyCode - The value in event.getKeyCode().
        event - Description of the key event.
        Returns:
        True if the key shortcut was handled.
      • onTouchEvent

        public boolean onTouchEvent(MotionEvent event)
        Called when a touch screen event was not handled by any of the views under it. This is most useful to process touch events that happen outside of your window bounds, where there is no view to receive it.
        Parameters:
        event - The touch screen event being processed.
        Returns:
        Return true if you have consumed the event, false if you haven't. The default implementation always returns false.
      • onTrackballEvent

        public boolean onTrackballEvent(MotionEvent event)
        Called when the trackball was moved and not handled by any of the views inside of the activity. So, for example, if the trackball moves while focus is on a button, you will receive a call here because buttons do not normally do anything with trackball events. The call here happens before trackball movements are converted to DPAD key events, which then get sent back to the view hierarchy, and will be processed at the point for things like focus navigation.
        Parameters:
        event - The trackball event being processed.
        Returns:
        Return true if you have consumed the event, false if you haven't. The default implementation always returns false.
      • onGenericMotionEvent

        public boolean onGenericMotionEvent(MotionEvent event)
        Called when a generic motion event was not handled by any of the views inside of the activity.

        Generic motion events describe joystick movements, mouse hovers, track pad touches, scroll wheel movements and other input events. The source of the motion event specifies the class of input that was received. Implementations of this method must examine the bits in the source before processing the event. The following code example shows how this is done.

        Generic motion events with source class InputDevice.SOURCE_CLASS_POINTER are delivered to the view under the pointer. All other generic motion events are delivered to the focused view.

        See View.onGenericMotionEvent(MotionEvent) for an example of how to handle this event.

        Parameters:
        event - The generic motion event being processed.
        Returns:
        Return true if you have consumed the event, false if you haven't. The default implementation always returns false.
      • onUserInteraction

        public void onUserInteraction()
        Called whenever a key, touch, or trackball event is dispatched to the activity. Implement this method if you wish to know that the user has interacted with the device in some way while your activity is running. This callback and onUserLeaveHint() are intended to help activities manage status bar notifications intelligently; specifically, for helping activities determine the proper time to cancel a notfication.

        All calls to your activity's onUserLeaveHint() callback will be accompanied by calls to onUserInteraction(). This ensures that your activity will be told of relevant user activity such as pulling down the notification pane and touching an item there.

        Note that this callback will be invoked for the touch down action that begins a touch gesture, but may not be invoked for the touch-moved and touch-up actions that follow.

        See Also:
        onUserLeaveHint()
      • onWindowFocusChanged

        public void onWindowFocusChanged(boolean hasFocus)
        Called when the current Window of the activity gains or loses focus. This is the best indicator of whether this activity is visible to the user. The default implementation clears the key tracking state, so should always be called.

        Note that this provides information about global focus state, which is managed independently of activity lifecycles. As such, while focus changes will generally have some relation to lifecycle changes (an activity that is stopped will not generally get window focus), you should not rely on any particular order between the callbacks here and those in the other lifecycle methods such as onResume().

        As a general rule, however, a resumed activity will have window focus... unless it has displayed other dialogs or popups that take input focus, in which case the activity itself will not have focus when the other windows have it. Likewise, the system may display system-level windows (such as the status bar notification panel or a system alert) which will temporarily take window input focus without pausing the foreground activity.

        Specified by:
        onWindowFocusChanged in interface Window.Callback
        Parameters:
        hasFocus - Whether the window of this activity has focus.
        See Also:
        hasWindowFocus(), onResume(), View.onWindowFocusChanged(boolean)
      • hasWindowFocus

        public boolean hasWindowFocus()
        Returns true if this activity's main window currently has window focus. Note that this is not the same as the view itself having focus.
        Returns:
        True if this activity's main window currently has window focus.
        See Also:
        onWindowAttributesChanged(android.view.WindowManager.LayoutParams)
      • dispatchKeyEvent

        public boolean dispatchKeyEvent(KeyEvent event)
        Called to process key events. You can override this to intercept all key events before they are dispatched to the window. Be sure to call this implementation for key events that should be handled normally.
        Specified by:
        dispatchKeyEvent in interface Window.Callback
        Parameters:
        event - The key event.
        Returns:
        boolean Return true if this event was consumed.
      • dispatchKeyShortcutEvent

        public boolean dispatchKeyShortcutEvent(KeyEvent event)
        Called to process a key shortcut event. You can override this to intercept all key shortcut events before they are dispatched to the window. Be sure to call this implementation for key shortcut events that should be handled normally.
        Specified by:
        dispatchKeyShortcutEvent in interface Window.Callback
        Parameters:
        event - The key shortcut event.
        Returns:
        True if this event was consumed.
      • dispatchTouchEvent

        public boolean dispatchTouchEvent(MotionEvent ev)
        Called to process touch screen events. You can override this to intercept all touch screen events before they are dispatched to the window. Be sure to call this implementation for touch screen events that should be handled normally.
        Specified by:
        dispatchTouchEvent in interface Window.Callback
        Parameters:
        ev - The touch screen event.
        Returns:
        boolean Return true if this event was consumed.
      • dispatchTrackballEvent

        public boolean dispatchTrackballEvent(MotionEvent ev)
        Called to process trackball events. You can override this to intercept all trackball events before they are dispatched to the window. Be sure to call this implementation for trackball events that should be handled normally.
        Specified by:
        dispatchTrackballEvent in interface Window.Callback
        Parameters:
        ev - The trackball event.
        Returns:
        boolean Return true if this event was consumed.
      • dispatchGenericMotionEvent

        public boolean dispatchGenericMotionEvent(MotionEvent ev)
        Called to process generic motion events. You can override this to intercept all generic motion events before they are dispatched to the window. Be sure to call this implementation for generic motion events that should be handled normally.
        Specified by:
        dispatchGenericMotionEvent in interface Window.Callback
        Parameters:
        ev - The generic motion event.
        Returns:
        boolean Return true if this event was consumed.
      • onMenuOpened

        public boolean onMenuOpened(int featureId,
                           Menu menu)
        Called when a panel's menu is opened by the user. This may also be called when the menu is changing from one type to another (for example, from the icon menu to the expanded menu).
        Specified by:
        onMenuOpened in interface Window.Callback
        Parameters:
        featureId - The panel that the menu is in.
        menu - The menu that is opened.
        Returns:
        The default implementation returns true.
      • invalidateOptionsMenu

        public void invalidateOptionsMenu()
        Declare that the options menu has changed, so should be recreated. The onCreateOptionsMenu(Menu) method will be called the next time it needs to be displayed.
      • onCreateOptionsMenu

        public boolean onCreateOptionsMenu(Menu menu)
        Initialize the contents of the Activity's standard options menu. You should place your menu items in to menu.

        This is only called once, the first time the options menu is displayed. To update the menu every time it is displayed, see onPrepareOptionsMenu(android.view.Menu).

        The default implementation populates the menu with standard system menu items. These are placed in the Menu.CATEGORY_SYSTEM group so that they will be correctly ordered with application-defined menu items. Deriving classes should always call through to the base implementation.

        You can safely hold on to menu (and any items created from it), making modifications to it as desired, until the next time onCreateOptionsMenu() is called.

        When you add items to the menu, you can implement the Activity's onOptionsItemSelected(android.view.MenuItem) method to handle them there.

        Parameters:
        menu - The options menu in which you place your items.
        Returns:
        You must return true for the menu to be displayed; if you return false it will not be shown.
        See Also:
        onPrepareOptionsMenu(android.view.Menu), onOptionsItemSelected(android.view.MenuItem)
      • onPrepareOptionsMenu

        public boolean onPrepareOptionsMenu(Menu menu)
        Prepare the Screen's standard options menu to be displayed. This is called right before the menu is shown, every time it is shown. You can use this method to efficiently enable/disable items or otherwise dynamically modify the contents.

        The default implementation updates the system menu items based on the activity's state. Deriving classes should always call through to the base class implementation.

        Parameters:
        menu - The options menu as last shown or first initialized by onCreateOptionsMenu().
        Returns:
        You must return true for the menu to be displayed; if you return false it will not be shown.
        See Also:
        onCreateOptionsMenu(android.view.Menu)
      • onOptionsItemSelected

        public boolean onOptionsItemSelected(MenuItem item)
        This hook is called whenever an item in your options menu is selected. The default implementation simply returns false to have the normal processing happen (calling the item's Runnable or sending a message to its Handler as appropriate). You can use this method for any items for which you would like to do processing without those other facilities.

        Derived classes should call through to the base class for it to perform the default menu handling.

        Parameters:
        item - The menu item that was selected.
        Returns:
        boolean Return false to allow normal menu processing to proceed, true to consume it here.
        See Also:
        onCreateOptionsMenu(android.view.Menu)
      • onNavigateUp

        public boolean onNavigateUp()
        This method is called whenever the user chooses to navigate Up within your application's activity hierarchy from the action bar.

        If the attribute parentActivityName was specified in the manifest for this activity or an activity-alias to it, default Up navigation will be handled automatically. If any activity along the parent chain requires extra Intent arguments, the Activity subclass should override the method onPrepareNavigateUpTaskStack(TaskStackBuilder) to supply those arguments.

        See Tasks and Back Stack from the developer guide and Navigation from the design guide for more information about navigating within your app.

        See the TaskStackBuilder class and the Activity methods getParentActivityIntent(), shouldUpRecreateTask(Intent), and navigateUpTo(Intent) for help implementing custom Up navigation. The AppNavigation sample application in the Android SDK is also available for reference.

        Returns:
        true if Up navigation completed successfully and this Activity was finished, false otherwise.
      • onNavigateUpFromChild

        public boolean onNavigateUpFromChild(Activity child)
        This is called when a child activity of this one attempts to navigate up. The default implementation simply calls onNavigateUp() on this activity (the parent).
        Parameters:
        child - The activity making the call.
      • onCreateNavigateUpTaskStack

        public void onCreateNavigateUpTaskStack(TaskStackBuilder builder)
        Define the synthetic task stack that will be generated during Up navigation from a different task.

        The default implementation of this method adds the parent chain of this activity as specified in the manifest to the supplied TaskStackBuilder. Applications may choose to override this method to construct the desired task stack in a different way.

        This method will be invoked by the default implementation of onNavigateUp() if shouldUpRecreateTask(Intent) returns true when supplied with the intent returned by getParentActivityIntent().

        Applications that wish to supply extra Intent parameters to the parent stack defined by the manifest should override onPrepareNavigateUpTaskStack(TaskStackBuilder).

        Parameters:
        builder - An empty TaskStackBuilder - the application should add intents representing the desired task stack
      • onPrepareNavigateUpTaskStack

        public void onPrepareNavigateUpTaskStack(TaskStackBuilder builder)
        Prepare the synthetic task stack that will be generated during Up navigation from a different task.

        This method receives the TaskStackBuilder with the constructed series of Intents as generated by onCreateNavigateUpTaskStack(TaskStackBuilder). If any extra data should be added to these intents before launching the new task, the application should override this method and add that data here.

        Parameters:
        builder - A TaskStackBuilder that has been populated with Intents by onCreateNavigateUpTaskStack.
      • onOptionsMenuClosed

        public void onOptionsMenuClosed(Menu menu)
        This hook is called whenever the options menu is being closed (either by the user canceling the menu with the back/menu button, or when an item is selected).
        Parameters:
        menu - The options menu as last shown or first initialized by onCreateOptionsMenu().
      • openOptionsMenu

        public void openOptionsMenu()
        Programmatically opens the options menu. If the options menu is already open, this method does nothing.
      • closeOptionsMenu

        public void closeOptionsMenu()
        Progammatically closes the options menu. If the options menu is already closed, this method does nothing.
      • onCreateContextMenu

        public void onCreateContextMenu(ContextMenu menu,
                               View v,
                               ContextMenu.ContextMenuInfo menuInfo)
        Called when a context menu for the view is about to be shown. Unlike onCreateOptionsMenu(Menu), this will be called every time the context menu is about to be shown and should be populated for the view (or item inside the view for AdapterView subclasses, this can be found in the menuInfo)).

        Use onContextItemSelected(android.view.MenuItem) to know when an item has been selected.

        It is not safe to hold onto the context menu after this method returns. Called when the context menu for this view is being built. It is not safe to hold onto the menu after this method returns.

        Specified by:
        onCreateContextMenu in interface View.OnCreateContextMenuListener
        Parameters:
        menu - The context menu that is being built
        v - The view for which the context menu is being built
        menuInfo - Extra information about the item for which the context menu should be shown. This information will vary depending on the class of v.
      • registerForContextMenu

        public void registerForContextMenu(View view)
        Registers a context menu to be shown for the given view (multiple views can show the context menu). This method will set the View.OnCreateContextMenuListener on the view to this activity, so #onCreateContextMenu(ContextMenu, View, ContextMenuInfo) will be called when it is time to show the context menu.
        Parameters:
        view - The view that should show a context menu.
        See Also:
        unregisterForContextMenu(View)
      • openContextMenu

        public void openContextMenu(View view)
        Programmatically opens the context menu for a particular view. The view should have been added via registerForContextMenu(View).
        Parameters:
        view - The view to show the context menu for.
      • closeContextMenu

        public void closeContextMenu()
        Programmatically closes the most recently opened context menu, if showing.
      • onContextItemSelected

        public boolean onContextItemSelected(MenuItem item)
        This hook is called whenever an item in a context menu is selected. The default implementation simply returns false to have the normal processing happen (calling the item's Runnable or sending a message to its Handler as appropriate). You can use this method for any items for which you would like to do processing without those other facilities.

        Use MenuItem.getMenuInfo() to get extra information set by the View that added this menu item.

        Derived classes should call through to the base class for it to perform the default menu handling.

        Parameters:
        item - The context menu item that was selected.
        Returns:
        boolean Return false to allow normal context menu processing to proceed, true to consume it here.
      • onContextMenuClosed

        public void onContextMenuClosed(Menu menu)
        This hook is called whenever the context menu is being closed (either by the user canceling the menu with the back/menu button, or when an item is selected).
        Parameters:
        menu - The context menu that is being closed.
      • onPrepareDialog

        @Deprecated
        protected void onPrepareDialog(int id,
                                      Dialog dialog,
                                      Bundle args)
        Deprecated. Use the new DialogFragment class with FragmentManager instead; this is also available on older platforms through the Android compatibility package.
        Provides an opportunity to prepare a managed dialog before it is being shown. The default implementation calls through to onPrepareDialog(int, Dialog) for compatibility.

        Override this if you need to update a managed dialog based on the state of the application each time it is shown. For example, a time picker dialog might want to be updated with the current time. You should call through to the superclass's implementation. The default implementation will set this Activity as the owner activity on the Dialog.

        Parameters:
        id - The id of the managed dialog.
        dialog - The dialog.
        args - The dialog arguments provided to showDialog(int, Bundle).
        See Also:
        onCreateDialog(int, Bundle), showDialog(int), dismissDialog(int), removeDialog(int)
      • onSearchRequested

        public boolean onSearchRequested()
        This hook is called when the user signals the desire to start a search.

        You can use this function as a simple way to launch the search UI, in response to a menu item, search button, or other widgets within your activity. Unless overidden, calling this function is the same as calling startSearch(null, false, null, false), which launches search for the current activity as specified in its manifest, see SearchManager.

        You can override this function to force global search, e.g. in response to a dedicated search key, or to block search entirely (by simply returning false).

        Specified by:
        onSearchRequested in interface Window.Callback
        Returns:
        Returns true if search launched, and false if activity blocks it. The default implementation always returns true.
        See Also:
        SearchManager
      • startSearch

        public void startSearch(String initialQuery,
                       boolean selectInitialQuery,
                       Bundle appSearchData,
                       boolean globalSearch)
        This hook is called to launch the search UI.

        It is typically called from onSearchRequested(), either directly from Activity.onSearchRequested() or from an overridden version in any given Activity. If your goal is simply to activate search, it is preferred to call onSearchRequested(), which may have been overriden elsewhere in your Activity. If your goal is to inject specific data such as context data, it is preferred to override onSearchRequested(), so that any callers to it will benefit from the override.

        Parameters:
        initialQuery - Any non-null non-empty string will be inserted as pre-entered text in the search query box.
        selectInitialQuery - If true, the intial query will be preselected, which means that any further typing will replace it. This is useful for cases where an entire pre-formed query is being inserted. If false, the selection point will be placed at the end of the inserted query. This is useful when the inserted query is text that the user entered, and the user would expect to be able to keep typing. This parameter is only meaningful if initialQuery is a non-empty string.
        appSearchData - An application can insert application-specific context here, in order to improve quality or specificity of its own searches. This data will be returned with SEARCH intent(s). Null if no extra data is required.
        globalSearch - If false, this will only launch the search that has been specifically defined by the application (which is usually defined as a local search). If no default search is defined in the current application or activity, global search will be launched. If true, this will always launch a platform-global (e.g. web-based) search instead.
        See Also:
        SearchManager, onSearchRequested()
      • triggerSearch

        public void triggerSearch(String query,
                         Bundle appSearchData)
        Similar to startSearch(java.lang.String, boolean, android.os.Bundle, boolean), but actually fires off the search query after invoking the search dialog. Made available for testing purposes.
        Parameters:
        query - The query to trigger. If empty, the request will be ignored.
        appSearchData - An application can insert application-specific context here, in order to improve quality or specificity of its own searches. This data will be returned with SEARCH intent(s). Null if no extra data is required.
      • takeKeyEvents

        public void takeKeyEvents(boolean get)
        Request that key events come to this activity. Use this if your activity has no views with focus, but the activity still wants a chance to process key events.
        See Also:
        Window.takeKeyEvents(boolean)
      • requestWindowFeature

        public final boolean requestWindowFeature(int featureId)
        Enable extended window features. This is a convenience for calling getWindow().requestFeature().
        Parameters:
        featureId - The desired feature as defined in Window.
        Returns:
        Returns true if the requested feature is supported and now enabled.
        See Also:
        Window.requestFeature(int)
      • startActivityForResult

        public void startActivityForResult(Intent intent,
                                  int requestCode,
                                  Bundle options)
        Launch an activity for which you would like a result when it finished. When this activity exits, your onActivityResult() method will be called with the given requestCode. Using a negative requestCode is the same as calling startActivity(android.content.Intent) (the activity is not launched as a sub-activity).

        Note that this method should only be used with Intent protocols that are defined to return a result. In other protocols (such as Intent.ACTION_MAIN or Intent.ACTION_VIEW), you may not get the result when you expect. For example, if the activity you are launching uses the singleTask launch mode, it will not run in your task and thus you will immediately receive a cancel result.

        As a special case, if you call startActivityForResult() with a requestCode >= 0 during the initial onCreate(Bundle savedInstanceState)/onResume() of your activity, then your window will not be displayed until a result is returned back from the started activity. This is to avoid visible flickering when redirecting to another activity.

        This method throws ActivityNotFoundException if there was no Activity found to run the given Intent.

        Parameters:
        intent - The intent to start.
        requestCode - If >= 0, this code will be returned in onActivityResult() when the activity exits.
        options - Additional options for how the Activity should be started. See Context.startActivity(Intent, Bundle) for more details.
        Throws:
        ActivityNotFoundException
        See Also:
        startActivity(android.content.Intent)
      • startActivityAsUser

        public void startActivityAsUser(Intent intent,
                               UserHandle user)
        Description copied from class: Context
        Version of Context.startActivity(Intent) that allows you to specify the user the activity will be started for. This is not available to applications that are not pre-installed on the system image. Using it requires holding the INTERACT_ACROSS_USERS_FULL permission.
        Overrides:
        startActivityAsUser in class ContextWrapper
        Parameters:
        intent - The description of the activity to start.
        user - The UserHandle of the user to start this activity for.
      • startActivityAsUser

        public void startActivityAsUser(Intent intent,
                               Bundle options,
                               UserHandle user)
        Description copied from class: Context
        Version of Context.startActivity(Intent, Bundle) that allows you to specify the user the activity will be started for. This is not available to applications that are not pre-installed on the system image. Using it requires holding the INTERACT_ACROSS_USERS_FULL permission.
        Overrides:
        startActivityAsUser in class ContextWrapper
        Parameters:
        intent - The description of the activity to start.
        options - Additional options for how the Activity should be started. May be null if there are no options. See ActivityOptions for how to build the Bundle supplied here; there are no supported definitions for building it manually.
      • startNextMatchingActivity

        public boolean startNextMatchingActivity(Intent intent)
        Same as calling startNextMatchingActivity(Intent, Bundle) with no options.
        Parameters:
        intent - The intent to dispatch to the next activity. For correct behavior, this must be the same as the Intent that started your own activity; the only changes you can make are to the extras inside of it.
        Returns:
        Returns a boolean indicating whether there was another Activity to start: true if there was a next activity to start, false if there wasn't. In general, if true is returned you will then want to call finish() on yourself.
      • startNextMatchingActivity

        public boolean startNextMatchingActivity(Intent intent,
                                        Bundle options)
        Special version of starting an activity, for use when you are replacing other activity components. You can use this to hand the Intent off to the next Activity that can handle it. You typically call this in onCreate(android.os.Bundle) with the Intent returned by getIntent().
        Parameters:
        intent - The intent to dispatch to the next activity. For correct behavior, this must be the same as the Intent that started your own activity; the only changes you can make are to the extras inside of it.
        options - Additional options for how the Activity should be started. See Context.startActivity(Intent, Bundle) for more details.
        Returns:
        Returns a boolean indicating whether there was another Activity to start: true if there was a next activity to start, false if there wasn't. In general, if true is returned you will then want to call finish() on yourself.
      • overridePendingTransition

        public void overridePendingTransition(int enterAnim,
                                     int exitAnim)
        Call immediately after one of the flavors of startActivity(Intent) or finish() to specify an explicit transition animation to perform next.

        As of Build.VERSION_CODES.JELLY_BEAN an alternative to using this with starting activities is to supply the desired animation information through a ActivityOptions bundle to {@link #startActivity(Intent, Bundle) or a related function. This allows you to specify a custom animation even when starting an activity from outside the context of the current top activity.

        Parameters:
        enterAnim - A resource ID of the animation resource to use for the incoming activity. Use 0 for no animation.
        exitAnim - A resource ID of the animation resource to use for the outgoing activity. Use 0 for no animation.
      • setResult

        public final void setResult(int resultCode)
        Call this to set the result that your activity will return to its caller.
        Parameters:
        resultCode - The result code to propagate back to the originating activity, often RESULT_CANCELED or RESULT_OK
        See Also:
        RESULT_CANCELED, RESULT_OK, RESULT_FIRST_USER, setResult(int, Intent)
      • setResult

        public final void setResult(int resultCode,
                     Intent data)
        Call this to set the result that your activity will return to its caller.

        As of Build.VERSION_CODES.GINGERBREAD, the Intent you supply here can have Intent.FLAG_GRANT_READ_URI_PERMISSION and/or Intent.FLAG_GRANT_WRITE_URI_PERMISSION set. This will grant the Activity receiving the result access to the specific URIs in the Intent. Access will remain until the Activity has finished (it will remain across the hosting process being killed and other temporary destruction) and will be added to any existing set of URI permissions it already holds.

        Parameters:
        resultCode - The result code to propagate back to the originating activity, often RESULT_CANCELED or RESULT_OK
        data - The data to propagate back to the originating activity.
        See Also:
        RESULT_CANCELED, RESULT_OK, RESULT_FIRST_USER, setResult(int)
      • getCallingPackage

        public String getCallingPackage()
        Return the name of the package that invoked this activity. This is who the data in setResult() will be sent to. You can use this information to validate that the recipient is allowed to receive the data.

        Note: if the calling activity is not expecting a result (that is it did not use the startActivityForResult(android.content.Intent, int) form that includes a request code), then the calling package will be null.

        Returns:
        The package of the activity that will receive your reply, or null if none.
      • getCallingActivity

        public ComponentName getCallingActivity()
        Return the name of the activity that invoked this activity. This is who the data in setResult() will be sent to. You can use this information to validate that the recipient is allowed to receive the data.

        Note: if the calling activity is not expecting a result (that is it did not use the startActivityForResult(android.content.Intent, int) form that includes a request code), then the calling package will be null.

        Returns:
        String The full name of the activity that will receive your reply, or null if none.
      • setVisible

        public void setVisible(boolean visible)
        Control whether this activity's main window is visible. This is intended only for the special case of an activity that is not going to show a UI itself, but can't just finish prior to onResume() because it needs to wait for a service binding or such. Setting this to false allows you to prevent your UI from being shown during that time.

        The default value for this is taken from the android.R.attr#windowNoDisplay attribute of the activity's theme.

      • isFinishing

        public boolean isFinishing()
        Check to see whether this activity is in the process of finishing, either because you called finish() on it or someone else has requested that it finished. This is often used in onPause() to determine whether the activity is simply pausing or completely finishing.
        Returns:
        If the activity is finishing, returns true; else returns false.
        See Also:
        finish()
      • isDestroyed

        public boolean isDestroyed()
        Returns true if the final onDestroy() call has been made on the Activity, so this instance is now dead.
      • isChangingConfigurations

        public boolean isChangingConfigurations()
        Check to see whether this activity is in the process of being destroyed in order to be recreated with a new configuration. This is often used in onStop() to determine whether the state needs to be cleaned up or will be passed on to the next instance of the activity via onRetainNonConfigurationInstance().
        Returns:
        If the activity is being torn down in order to be recreated with a new configuration, returns true; else returns false.
      • recreate

        public void recreate()
        Cause this Activity to be recreated with a new instance. This results in essentially the same flow as when the Activity is created due to a configuration change -- the current instance will go through its lifecycle to onDestroy() and a new instance then created after it.
      • finish

        public void finish()
        Call this when your activity is done and should be closed. The ActivityResult is propagated back to whoever launched you via onActivityResult().
      • finishAffinity

        public void finishAffinity()
        Finish this activity as well as all activities immediately below it in the current task that have the same affinity. This is typically used when an application can be launched on to another task (such as from an ACTION_VIEW of a content type it understands) and the user has used the up navigation to switch out of the current task and in to its own task. In this case, if the user has navigated down into any other activities of the second application, all of those should be removed from the original task as part of the task switch.

        Note that this finish does not allow you to deliver results to the previous activity, and an exception will be thrown if you are trying to do so.

      • finishFromChild

        public void finishFromChild(Activity child)
        This is called when a child activity of this one calls its finish() method. The default implementation simply calls finish() on this activity (the parent), finishing the entire group.
        Parameters:
        child - The activity making the call.
        See Also:
        finish()
      • finishActivity

        public void finishActivity(int requestCode)
        Force finish another activity that you had previously started with startActivityForResult(android.content.Intent, int).
        Parameters:
        requestCode - The request code of the activity that you had given to startActivityForResult(). If there are multiple activities started with this request code, they will all be finished.
      • finishActivityFromChild

        public void finishActivityFromChild(Activity child,
                                   int requestCode)
        This is called when a child activity of this one calls its finishActivity().
        Parameters:
        child - The activity making the call.
        requestCode - Request code that had been used to start the activity.
      • onActivityResult

        protected void onActivityResult(int requestCode,
                            int resultCode,
                            Intent data)
        Called when an activity you launched exits, giving you the requestCode you started it with, the resultCode it returned, and any additional data from it. The resultCode will be RESULT_CANCELED if the activity explicitly returned that, didn't return any result, or crashed during its operation.

        You will receive this call immediately before onResume() when your activity is re-starting.

        Parameters:
        requestCode - The integer request code originally supplied to startActivityForResult(), allowing you to identify who this result came from.
        resultCode - The integer result code returned by the child activity through its setResult().
        data - An Intent, which can return result data to the caller (various data can be attached to Intent "extras").
        See Also:
        startActivityForResult(android.content.Intent, int), createPendingResult(int, android.content.Intent, int), setResult(int)
      • setRequestedOrientation

        public void setRequestedOrientation(int requestedOrientation)
        Change the desired orientation of this activity. If the activity is currently in the foreground or otherwise impacting the screen orientation, the screen will immediately be changed (possibly causing the activity to be restarted). Otherwise, this will be used the next time the activity is visible.
        Parameters:
        requestedOrientation - An orientation constant as used in ActivityInfo.screenOrientation.
      • getRequestedOrientation

        public int getRequestedOrientation()
        Return the current requested orientation of the activity. This will either be the orientation requested in its component's manifest, or the last requested orientation given to setRequestedOrientation(int).
        Returns:
        Returns an orientation constant as used in ActivityInfo.screenOrientation.
      • getTaskId

        public int getTaskId()
        Return the identifier of the task this activity is in. This identifier will remain the same for the lifetime of the activity.
        Returns:
        Task identifier, an opaque integer.
      • isTaskRoot

        public boolean isTaskRoot()
        Return whether this activity is the root of a task. The root is the first activity in a task.
        Returns:
        True if this is the root activity, else false.
      • moveTaskToBack

        public boolean moveTaskToBack(boolean nonRoot)
        Move the task containing this activity to the back of the activity stack. The activity's order within the task is unchanged.
        Parameters:
        nonRoot - If false then this only works if the activity is the root of a task; if true it will work for any activity in a task.
        Returns:
        If the task was moved (or it was already at the back) true is returned, else false.
      • getLocalClassName

        public String getLocalClassName()
        Returns class name for this activity with the package prefix removed. This is the default name used to read and write settings.
        Returns:
        The local class name.
      • getComponentName

        public ComponentName getComponentName()
        Returns complete component name of this activity.
        Returns:
        Returns the complete component name for this activity
      • setTitle

        public void setTitle(CharSequence title)
        Change the title associated with this activity. If this is a top-level activity, the title for its window will change. If it is an embedded activity, the parent can do whatever it wants with it.
      • setTitle

        public void setTitle(int titleId)
        Change the title associated with this activity. If this is a top-level activity, the title for its window will change. If it is an embedded activity, the parent can do whatever it wants with it.
      • setTitleColor

        public void setTitleColor(int textColor)
      • getTitleColor

        public final int getTitleColor()
      • onTitleChanged

        protected void onTitleChanged(CharSequence title,
                          int color)
      • onChildTitleChanged

        protected void onChildTitleChanged(Activity childActivity,
                               CharSequence title)
      • setProgressBarVisibility

        public final void setProgressBarVisibility(boolean visible)
        Sets the visibility of the progress bar in the title.

        In order for the progress bar to be shown, the feature must be requested via requestWindowFeature(int).

        Parameters:
        visible - Whether to show the progress bars in the title.
      • setProgressBarIndeterminateVisibility

        public final void setProgressBarIndeterminateVisibility(boolean visible)
        Sets the visibility of the indeterminate progress bar in the title.

        In order for the progress bar to be shown, the feature must be requested via requestWindowFeature(int).

        Parameters:
        visible - Whether to show the progress bars in the title.
      • setProgressBarIndeterminate

        public final void setProgressBarIndeterminate(boolean indeterminate)
        Sets whether the horizontal progress bar in the title should be indeterminate (the circular is always indeterminate).

        In order for the progress bar to be shown, the feature must be requested via requestWindowFeature(int).

        Parameters:
        indeterminate - Whether the horizontal progress bar should be indeterminate.
      • setProgress

        public final void setProgress(int progress)
        Sets the progress for the progress bars in the title.

        In order for the progress bar to be shown, the feature must be requested via requestWindowFeature(int).

        Parameters:
        progress - The progress for the progress bar. Valid ranges are from 0 to 10000 (both inclusive). If 10000 is given, the progress bar will be completely filled and will fade out.
      • setSecondaryProgress

        public final void setSecondaryProgress(int secondaryProgress)
        Sets the secondary progress for the progress bar in the title. This progress is drawn between the primary progress (set via setProgress(int) and the background. It can be ideal for media scenarios such as showing the buffering progress while the default progress shows the play progress.

        In order for the progress bar to be shown, the feature must be requested via requestWindowFeature(int).

        Parameters:
        secondaryProgress - The secondary progress for the progress bar. Valid ranges are from 0 to 10000 (both inclusive).
      • setVolumeControlStream

        public final void setVolumeControlStream(int streamType)
        Suggests an audio stream whose volume should be changed by the hardware volume controls.

        The suggested audio stream will be tied to the window of this Activity. If the Activity is switched, the stream set here is no longer the suggested stream. The client does not need to save and restore the old suggested stream value in onPause and onResume.

        Parameters:
        streamType - The type of the audio stream whose volume should be changed by the hardware volume controls. It is not guaranteed that the hardware volume controls will always change this stream's volume (for example, if a call is in progress, its stream's volume may be changed instead). To reset back to the default, use AudioManager.USE_DEFAULT_STREAM_TYPE.
      • getVolumeControlStream

        public final int getVolumeControlStream()
        Gets the suggested audio stream whose volume should be changed by the harwdare volume controls.
        Returns:
        The suggested audio stream type whose volume should be changed by the hardware volume controls.
        See Also:
        setVolumeControlStream(int)
      • runOnUiThread

        public final void runOnUiThread(Runnable action)
        Runs the specified action on the UI thread. If the current thread is the UI thread, then the action is executed immediately. If the current thread is not the UI thread, the action is posted to the event queue of the UI thread.
        Parameters:
        action - the action to run on the UI thread
      • dump

        public void dump(String prefix,
                FileDescriptor fd,
                PrintWriter writer,
                String[] args)
        Print the Activity's state into the given stream. This gets invoked if you run "adb shell dumpsys activity <activity_component_name>".
        Parameters:
        prefix - Desired prefix to prepend at each line of output.
        fd - The raw file descriptor that the dump is being sent to.
        writer - The PrintWriter to which you should dump your state. This will be closed for you after you return.
        args - additional arguments to the dump request.
      • isImmersive

        public boolean isImmersive()
        Bit indicating that this activity is "immersive" and should not be interrupted by notifications if possible. This value is initially set by the manifest property android:immersive but may be changed at runtime by setImmersive(boolean).
        See Also:
        ActivityInfo.FLAG_IMMERSIVE
      • startActionMode

        public ActionMode startActionMode(ActionMode.Callback callback)
        Start an action mode.
        Parameters:
        callback - Callback that will manage lifecycle events for this context mode
        Returns:
        The ContextMode that was started, or null if it was canceled
        See Also:
        ActionMode
      • onWindowStartingActionMode

        public ActionMode onWindowStartingActionMode(ActionMode.Callback callback)
        Give the Activity a chance to control the UI for an action mode requested by the system.

        Note: If you are looking for a notification callback that an action mode has been started for this activity, see onActionModeStarted(ActionMode).

        Specified by:
        onWindowStartingActionMode in interface Window.Callback
        Parameters:
        callback - The callback that should control the new action mode
        Returns:
        The new action mode, or null if the activity does not want to provide special handling for this action mode. (It will be handled by the system.)
      • onActionModeStarted

        public void onActionModeStarted(ActionMode mode)
        Notifies the Activity that an action mode has been started. Activity subclasses overriding this method should call the superclass implementation.
        Specified by:
        onActionModeStarted in interface Window.Callback
        Parameters:
        mode - The new action mode.
      • onActionModeFinished

        public void onActionModeFinished(ActionMode mode)
        Notifies the activity that an action mode has finished. Activity subclasses overriding this method should call the superclass implementation.
        Specified by:
        onActionModeFinished in interface Window.Callback
        Parameters:
        mode - The action mode that just finished.
      • shouldUpRecreateTask

        public boolean shouldUpRecreateTask(Intent targetIntent)
        Returns true if the app should recreate the task when navigating 'up' from this activity by using targetIntent.

        If this method returns false the app can trivially call navigateUpTo(Intent) using the same parameters to correctly perform up navigation. If this method returns false, the app should synthesize a new task stack by using TaskStackBuilder or another similar mechanism to perform up navigation.

        Parameters:
        targetIntent - An intent representing the target destination for up navigation
        Returns:
        true if navigating up should recreate a new task stack, false if the same task should be used for the destination
      • navigateUpTo

        public boolean navigateUpTo(Intent upIntent)
        Navigate from this activity to the activity specified by upIntent, finishing this activity in the process. If the activity indicated by upIntent already exists in the task's history, this activity and all others before the indicated activity in the history stack will be finished.

        If the indicated activity does not appear in the history stack, this will finish each activity in this task until the root activity of the task is reached, resulting in an "in-app home" behavior. This can be useful in apps with a complex navigation hierarchy when an activity may be reached by a path not passing through a canonical parent activity.

        This method should be used when performing up navigation from within the same task as the destination. If up navigation should cross tasks in some cases, see shouldUpRecreateTask(Intent).

        Parameters:
        upIntent - An intent representing the target destination for up navigation
        Returns:
        true if up navigation successfully reached the activity indicated by upIntent and upIntent was delivered to it. false if an instance of the indicated activity could not be found and this activity was simply finished normally.
      • navigateUpToFromChild

        public boolean navigateUpToFromChild(Activity child,
                                    Intent upIntent)
        This is called when a child activity of this one calls its navigateUpTo(android.content.Intent) method. The default implementation simply calls navigateUpTo(upIntent) on this activity (the parent).
        Parameters:
        child - The activity making the call.
        upIntent - An intent representing the target destination for up navigation
        Returns:
        true if up navigation successfully reached the activity indicated by upIntent and upIntent was delivered to it. false if an instance of the indicated activity could not be found and this activity was simply finished normally.
      • getParentActivityIntent

        public Intent getParentActivityIntent()
        Obtain an Intent that will launch an explicit target activity specified by this activity's logical parent. The logical parent is named in the application's manifest by the parentActivityName attribute. Activity subclasses may override this method to modify the Intent returned by super.getParentActivityIntent() or to implement a different mechanism of retrieving the parent intent entirely.
        Returns:
        a new Intent targeting the defined parent of this activity or null if there is no valid parent.
      • getActivityToken

        public final IBinder getActivityToken()
      • isResumed

        public final boolean isResumed()


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