public class ListActivity extends Activity
ListActivity hosts a ListView
object that can
be bound to different data sources, typically either an array or a Cursor
holding query results. Binding, screen layout, and row layout are discussed
in the following sections.
Screen Layout
ListActivity has a default layout that consists of a single, full-screen list
in the center of the screen. However, if you desire, you can customize the
screen layout by setting your own view layout with setContentView() in
onCreate(). To do this, your own view MUST contain a ListView object with the
id "@android:id/list" (or android.R.id#list
if it's in code)
Optionally, your custom view can contain another view object of any type to display when the list view is empty. This "empty list" notifier must have an id "android:id/empty". Note that when an empty view is present, the list view will be hidden when there is no data to display.
The following code demonstrates an (ugly) custom screen layout. It has a list with a green background, and an alternate red "no data" message.
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingLeft="8dp" android:paddingRight="8dp"> <ListView android:id="@android:id/list" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#00FF00" android:layout_weight="1" android:drawSelectorOnTop="false"/> <TextView android:id="@android:id/empty" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#FF0000" android:text="No data"/> </LinearLayout>
Row Layout
You can specify the layout of individual rows in the list. You do this by specifying a layout resource in the ListAdapter object hosted by the activity (the ListAdapter binds the ListView to the data; more on this later).
A ListAdapter constructor takes a parameter that specifies a layout resource for each row. It also has two additional parameters that let you specify which data field to associate with which object in the row layout resource. These two parameters are typically parallel arrays.
Android provides some standard row layout resources. These are in the
android.R.layout
class, and have names such as simple_list_item_1,
simple_list_item_2, and two_line_list_item. The following layout XML is the
source for the resource two_line_list_item, which displays two data
fields,one above the other, for each list row.
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical"> <TextView android:id="@+id/text1" android:textSize="16sp" android:textStyle="bold" android:layout_width="match_parent" android:layout_height="wrap_content"/> <TextView android:id="@+id/text2" android:textSize="16sp" android:layout_width="match_parent" android:layout_height="wrap_content"/> </LinearLayout>
You must identify the data bound to each TextView object in this layout. The syntax for this is discussed in the next section.
Binding to Data
You bind the ListActivity's ListView object to data using a class that
implements the ListAdapter
interface.
Android provides two standard list adapters:
SimpleAdapter
for static data (Maps),
and SimpleCursorAdapter
for Cursor
query results.
The following code from a custom ListActivity demonstrates querying the Contacts provider for all contacts, then binding the Name and Company fields to a two line row layout in the activity's ListView.
public class MyListAdapter extends ListActivity {
@Override
protected void onCreate(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
// We'll define a custom screen layout here (the one shown above), but
// typically, you could just use the standard ListActivity layout.
setContentView(R.layout.custom_list_activity_view);
// Query for all people contacts using the Contacts.People
convenience class.
// Put a managed wrapper around the retrieved cursor so we don't have to worry about
// requerying or closing it as the activity changes state.
mCursor = this.getContentResolver().query(People.CONTENT_URI, null, null, null, null);
startManagingCursor(mCursor);
// Now create a new list adapter bound to the cursor.
// SimpleListAdapter is designed for binding to a Cursor.
ListAdapter adapter = new SimpleCursorAdapter(
this, // Context.
android.R.layout.two_line_list_item, // Specify the row template to use (here, two columns bound to the two retrieved cursor
rows).
mCursor, // Pass in the cursor to bind to.
new String[] {People.NAME, People.COMPANY}, // Array of cursor columns to bind to.
new int[] {android.R.id.text1, android.R.id.text2}); // Parallel array of which template objects to bind to those columns.
// Bind to our new adapter.
setListAdapter(adapter);
}
}
Modifier and Type | Field and Description |
---|---|
protected ListAdapter |
mAdapter
This field should be made private, so it is hidden from the SDK.
|
protected ListView |
mList
This field should be made private, so it is hidden from the SDK.
|
DEFAULT_KEYS_DIALER, DEFAULT_KEYS_DISABLE, DEFAULT_KEYS_SEARCH_GLOBAL, DEFAULT_KEYS_SEARCH_LOCAL, DEFAULT_KEYS_SHORTCUT, FOCUSED_STATE_SET, RESULT_CANCELED, RESULT_FIRST_USER, RESULT_OK
ACCESSIBILITY_SERVICE, ACCOUNT_SERVICE, ACTIVITY_SERVICE, ALARM_SERVICE, APPWIDGET_SERVICE, AUDIO_SERVICE, BACKUP_SERVICE, BIND_ABOVE_CLIENT, BIND_ADJUST_WITH_ACTIVITY, BIND_ALLOW_OOM_MANAGEMENT, BIND_AUTO_CREATE, BIND_DEBUG_UNBIND, BIND_IMPORTANT, BIND_NOT_FOREGROUND, BIND_NOT_VISIBLE, BIND_VISIBLE, BIND_WAIVE_PRIORITY, BLUETOOTH_SERVICE, CLIPBOARD_SERVICE, CONNECTIVITY_SERVICE, CONTEXT_IGNORE_SECURITY, CONTEXT_INCLUDE_CODE, CONTEXT_RESTRICTED, COUNTRY_DETECTOR, DEVICE_POLICY_SERVICE, DISPLAY_SERVICE, DOWNLOAD_SERVICE, DROPBOX_SERVICE, INPUT_METHOD_SERVICE, INPUT_SERVICE, KEYGUARD_SERVICE, LAYOUT_INFLATER_SERVICE, LOCATION_SERVICE, MEDIA_ROUTER_SERVICE, MODE_APPEND, MODE_ENABLE_WRITE_AHEAD_LOGGING, MODE_MULTI_PROCESS, MODE_PRIVATE, MODE_WORLD_READABLE, MODE_WORLD_WRITEABLE, NETWORK_POLICY_SERVICE, NETWORK_STATS_SERVICE, NETWORKMANAGEMENT_SERVICE, NFC_SERVICE, NOTIFICATION_SERVICE, NSD_SERVICE, POWER_SERVICE, SCHEDULING_POLICY_SERVICE, SEARCH_SERVICE, SENSOR_SERVICE, SERIAL_SERVICE, SIP_SERVICE, STATUS_BAR_SERVICE, STORAGE_SERVICE, TELEPHONY_SERVICE, TEXT_SERVICES_MANAGER_SERVICE, THROTTLE_SERVICE, UI_MODE_SERVICE, UPDATE_LOCK_SERVICE, USB_SERVICE, USER_SERVICE, VIBRATOR_SERVICE, WALLPAPER_SERVICE, WIFI_P2P_SERVICE, WIFI_SERVICE, WINDOW_SERVICE
TRIM_MEMORY_BACKGROUND, TRIM_MEMORY_COMPLETE, TRIM_MEMORY_MODERATE, TRIM_MEMORY_RUNNING_CRITICAL, TRIM_MEMORY_RUNNING_LOW, TRIM_MEMORY_RUNNING_MODERATE, TRIM_MEMORY_UI_HIDDEN
Constructor and Description |
---|
ListActivity() |
Modifier and Type | Method and Description |
---|---|
ListAdapter |
getListAdapter()
Get the ListAdapter associated with this activity's ListView.
|
ListView |
getListView()
Get the activity's list view widget.
|
long |
getSelectedItemId()
Get the cursor row ID of the currently selected list item.
|
int |
getSelectedItemPosition()
Get the position of the currently selected list item.
|
void |
onContentChanged()
Updates the screen state (current list and other views) when the
content changes.
|
protected void |
onDestroy()
Perform any final cleanup before an activity is destroyed.
|
protected void |
onListItemClick(ListView l,
View v,
int position,
long id)
This method will be called when an item in the list is selected.
|
protected void |
onRestoreInstanceState(Bundle state)
Ensures the list view has been created before Activity restores all
of the view states.
|
void |
setListAdapter(ListAdapter adapter)
Provide the cursor for the list view.
|
void |
setSelection(int position)
Set the currently selected list item to the specified
position with the adapter's data
|
addContentView, closeContextMenu, closeOptionsMenu, createPendingResult, dismissDialog, dispatchGenericMotionEvent, dispatchKeyEvent, dispatchKeyShortcutEvent, dispatchPopulateAccessibilityEvent, dispatchTouchEvent, dispatchTrackballEvent, dump, findViewById, finish, finishActivity, finishActivityFromChild, finishAffinity, finishFromChild, getActionBar, getActivityToken, getApplication, getCallingActivity, getCallingPackage, getChangingConfigurations, getComponentName, getCurrentFocus, getFragmentManager, getIntent, getLastNonConfigurationInstance, getLayoutInflater, getLoaderManager, getLocalClassName, getMenuInflater, getParent, getParentActivityIntent, getPreferences, getRequestedOrientation, getSystemService, getTaskId, getTitle, getTitleColor, getVolumeControlStream, getWindow, getWindowManager, hasWindowFocus, invalidateOptionsMenu, isChangingConfigurations, isChild, isDestroyed, isFinishing, isImmersive, isResumed, isTaskRoot, managedQuery, managedQuery, moveTaskToBack, navigateUpTo, navigateUpToFromChild, onActionModeFinished, onActionModeStarted, onActivityResult, onApplyThemeResource, onAttachedToWindow, onAttachFragment, onBackPressed, onChildTitleChanged, onConfigurationChanged, onContextItemSelected, onContextMenuClosed, onCreate, onCreateContextMenu, onCreateDescription, onCreateDialog, onCreateDialog, onCreateNavigateUpTaskStack, onCreateOptionsMenu, onCreatePanelMenu, onCreatePanelView, onCreateThumbnail, onCreateView, onCreateView, onDetachedFromWindow, onGenericMotionEvent, onKeyDown, onKeyLongPress, onKeyMultiple, onKeyShortcut, onKeyUp, onLowMemory, onMenuItemSelected, onMenuOpened, onNavigateUp, onNavigateUpFromChild, onNewIntent, onOptionsItemSelected, onOptionsMenuClosed, onPanelClosed, onPause, onPostCreate, onPostResume, onPrepareDialog, onPrepareDialog, onPrepareNavigateUpTaskStack, onPrepareOptionsMenu, onPreparePanel, onRestart, onResume, onRetainNonConfigurationInstance, onSaveInstanceState, onSearchRequested, onStart, onStop, onTitleChanged, onTouchEvent, onTrackballEvent, onTrimMemory, onUserInteraction, onUserLeaveHint, onWindowAttributesChanged, onWindowFocusChanged, onWindowStartingActionMode, openContextMenu, openOptionsMenu, overridePendingTransition, recreate, registerForContextMenu, removeDialog, requestWindowFeature, runOnUiThread, setContentView, setContentView, setContentView, setDefaultKeyMode, setFeatureDrawable, setFeatureDrawableAlpha, setFeatureDrawableResource, setFeatureDrawableUri, setFinishOnTouchOutside, setImmersive, setIntent, setPersistent, setProgress, setProgressBarIndeterminate, setProgressBarIndeterminateVisibility, setProgressBarVisibility, setRequestedOrientation, setResult, setResult, setSecondaryProgress, setTitle, setTitle, setTitleColor, setVisible, setVolumeControlStream, shouldUpRecreateTask, showDialog, showDialog, startActionMode, startActivities, startActivities, startActivity, startActivity, startActivityAsUser, startActivityAsUser, startActivityForResult, startActivityForResult, startActivityFromChild, startActivityFromChild, startActivityFromFragment, startActivityFromFragment, startActivityIfNeeded, startActivityIfNeeded, startIntentSender, startIntentSender, startIntentSenderForResult, startIntentSenderForResult, startIntentSenderFromChild, startIntentSenderFromChild, startManagingCursor, startNextMatchingActivity, startNextMatchingActivity, startSearch, stopManagingCursor, takeKeyEvents, triggerSearch, unregisterForContextMenu
applyOverrideConfiguration, attachBaseContext, getResources, getTheme, getThemeResId, setTheme
bindService, bindService, checkCallingOrSelfPermission, checkCallingOrSelfUriPermission, checkCallingPermission, checkCallingUriPermission, checkPermission, checkUriPermission, checkUriPermission, clearWallpaper, createConfigurationContext, createDisplayContext, createPackageContext, createPackageContextAsUser, databaseList, deleteDatabase, deleteFile, enforceCallingOrSelfPermission, enforceCallingOrSelfUriPermission, enforceCallingPermission, enforceCallingUriPermission, enforcePermission, enforceUriPermission, enforceUriPermission, fileList, getApplicationContext, getApplicationInfo, getAssets, getBaseContext, getCacheDir, getClassLoader, getCompatibilityInfo, getContentResolver, getDatabasePath, getDir, getExternalCacheDir, getExternalFilesDir, getFilesDir, getFileStreamPath, getMainLooper, getObbDir, getPackageCodePath, getPackageManager, getPackageName, getPackageResourcePath, getSharedPreferences, getSharedPrefsFile, getWallpaper, getWallpaperDesiredMinimumHeight, getWallpaperDesiredMinimumWidth, grantUriPermission, isRestricted, openFileInput, openFileOutput, openOrCreateDatabase, openOrCreateDatabase, peekWallpaper, registerReceiver, registerReceiver, registerReceiverAsUser, removeStickyBroadcast, removeStickyBroadcastAsUser, revokeUriPermission, sendBroadcast, sendBroadcast, sendBroadcastAsUser, sendBroadcastAsUser, sendOrderedBroadcast, sendOrderedBroadcast, sendOrderedBroadcastAsUser, sendStickyBroadcast, sendStickyBroadcastAsUser, sendStickyOrderedBroadcast, sendStickyOrderedBroadcastAsUser, setWallpaper, setWallpaper, startActivitiesAsUser, startInstrumentation, startService, startServiceAsUser, stopService, stopServiceAsUser, unbindService, unregisterReceiver
getString, getString, getText, obtainStyledAttributes, obtainStyledAttributes, obtainStyledAttributes, obtainStyledAttributes, registerComponentCallbacks, unregisterComponentCallbacks
protected ListAdapter mAdapter
protected ListView mList
protected void onListItemClick(ListView l, View v, int position, long id)
l
- The ListView where the click happenedv
- The view that was clicked within the ListViewposition
- The position of the view in the listid
- The row id of the item that was clickedprotected void onRestoreInstanceState(Bundle state)
onRestoreInstanceState
in class Activity
state
- the data most recently supplied in Activity.onSaveInstanceState(android.os.Bundle)
.Activity.onRestoreInstanceState(Bundle)
protected void onDestroy()
Activity
Activity.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 Activity.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 Activity.onPause()
or
Activity.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.
onDestroy
in class Activity
Activity.onDestroy()
public void onContentChanged()
onContentChanged
in interface Window.Callback
onContentChanged
in class Activity
Activity.onContentChanged()
public void setListAdapter(ListAdapter adapter)
public void setSelection(int position)
position
- public int getSelectedItemPosition()
public long getSelectedItemId()
public ListView getListView()
public ListAdapter getListAdapter()