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JSONObject


org.json

Class JSONObject



  • public class JSONObject
    extends Object
    A modifiable set of name/value mappings. Names are unique, non-null strings. Values may be any mix of JSONObjects, JSONArrays, Strings, Booleans, Integers, Longs, Doubles or NULL. Values may not be null, NaNs, infinities, or of any type not listed here.

    This class can coerce values to another type when requested.

    • When the requested type is a boolean, strings will be coerced using a case-insensitive comparison to "true" and "false".
    • When the requested type is a double, other Number types will be coerced using doubleValue. Strings that can be coerced using Double.valueOf(String) will be.
    • When the requested type is an int, other Number types will be coerced using intValue. Strings that can be coerced using Double.valueOf(String) will be, and then cast to int.
    • When the requested type is a long, other Number types will be coerced using longValue. Strings that can be coerced using Double.valueOf(String) will be, and then cast to long. This two-step conversion is lossy for very large values. For example, the string "9223372036854775806" yields the long 9223372036854775807.
    • When the requested type is a String, other non-null values will be coerced using String.valueOf(Object). Although null cannot be coerced, the sentinel value NULL is coerced to the string "null".

    This class can look up both mandatory and optional values:

    • Use getType() to retrieve a mandatory value. This fails with a JSONException if the requested name has no value or if the value cannot be coerced to the requested type.
    • Use optType() to retrieve an optional value. This returns a system- or user-supplied default if the requested name has no value or if the value cannot be coerced to the requested type.

    Warning: this class represents null in two incompatible ways: the standard Java null reference, and the sentinel value NULL. In particular, calling put(name, null) removes the named entry from the object but put(name, JSONObject.NULL) stores an entry whose value is JSONObject.NULL.

    Instances of this class are not thread safe. Although this class is nonfinal, it was not designed for inheritance and should not be subclassed. In particular, self-use by overrideable methods is not specified. See Effective Java Item 17, "Design and Document or inheritance or else prohibit it" for further information.

    • Field Summary

      Fields
      Modifier and Type Field and Description
      static Object NULL
      A sentinel value used to explicitly define a name with no value.
    • Constructor Summary

      Constructors
      Constructor and Description
      JSONObject()
      Creates a JSONObject with no name/value mappings.
      JSONObject(JSONObject copyFrom, String[] names)
      Creates a new JSONObject by copying mappings for the listed names from the given object.
      JSONObject(JSONTokener readFrom)
      Creates a new JSONObject with name/value mappings from the next object in the tokener.
      JSONObject(Map copyFrom)
      Creates a new JSONObject by copying all name/value mappings from the given map.
      JSONObject(String json)
      Creates a new JSONObject with name/value mappings from the JSON string.
    • Method Summary

      Methods
      Modifier and Type Method and Description
      JSONObject accumulate(String name, Object value)
      Appends value to the array already mapped to name.
      Object get(String name)
      Returns the value mapped by name.
      boolean getBoolean(String name)
      Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean.
      double getDouble(String name)
      Returns the value mapped by name if it exists and is a double or can be coerced to a double.
      int getInt(String name)
      Returns the value mapped by name if it exists and is an int or can be coerced to an int.
      JSONArray getJSONArray(String name)
      Returns the value mapped by name if it exists and is a JSONArray.
      JSONObject getJSONObject(String name)
      Returns the value mapped by name if it exists and is a JSONObject.
      long getLong(String name)
      Returns the value mapped by name if it exists and is a long or can be coerced to a long.
      String getString(String name)
      Returns the value mapped by name if it exists, coercing it if necessary.
      boolean has(String name)
      Returns true if this object has a mapping for name.
      boolean isNull(String name)
      Returns true if this object has no mapping for name or if it has a mapping whose value is NULL.
      Iterator keys()
      Returns an iterator of the String names in this object.
      int length()
      Returns the number of name/value mappings in this object.
      JSONArray names()
      Returns an array containing the string names in this object.
      static String numberToString(Number number)
      Encodes the number as a JSON string.
      Object opt(String name)
      Returns the value mapped by name, or null if no such mapping exists.
      boolean optBoolean(String name)
      Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean.
      boolean optBoolean(String name, boolean fallback)
      Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean.
      double optDouble(String name)
      Returns the value mapped by name if it exists and is a double or can be coerced to a double.
      double optDouble(String name, double fallback)
      Returns the value mapped by name if it exists and is a double or can be coerced to a double.
      int optInt(String name)
      Returns the value mapped by name if it exists and is an int or can be coerced to an int.
      int optInt(String name, int fallback)
      Returns the value mapped by name if it exists and is an int or can be coerced to an int.
      JSONArray optJSONArray(String name)
      Returns the value mapped by name if it exists and is a JSONArray.
      JSONObject optJSONObject(String name)
      Returns the value mapped by name if it exists and is a JSONObject.
      long optLong(String name)
      Returns the value mapped by name if it exists and is a long or can be coerced to a long.
      long optLong(String name, long fallback)
      Returns the value mapped by name if it exists and is a long or can be coerced to a long.
      String optString(String name)
      Returns the value mapped by name if it exists, coercing it if necessary.
      String optString(String name, String fallback)
      Returns the value mapped by name if it exists, coercing it if necessary.
      JSONObject put(String name, boolean value)
      Maps name to value, clobbering any existing name/value mapping with the same name.
      JSONObject put(String name, double value)
      Maps name to value, clobbering any existing name/value mapping with the same name.
      JSONObject put(String name, int value)
      Maps name to value, clobbering any existing name/value mapping with the same name.
      JSONObject put(String name, long value)
      Maps name to value, clobbering any existing name/value mapping with the same name.
      JSONObject put(String name, Object value)
      Maps name to value, clobbering any existing name/value mapping with the same name.
      JSONObject putOpt(String name, Object value)
      Equivalent to put(name, value) when both parameters are non-null; does nothing otherwise.
      static String quote(String data)
      Encodes data as a JSON string.
      Object remove(String name)
      Removes the named mapping if it exists; does nothing otherwise.
      JSONArray toJSONArray(JSONArray names)
      Returns an array with the values corresponding to names.
      String toString()
      Encodes this object as a compact JSON string, such as:
      String toString(int indentSpaces)
      Encodes this object as a human readable JSON string for debugging, such as:
    • Field Detail

      • NULL

        public static final Object NULL
        A sentinel value used to explicitly define a name with no value. Unlike null, names with this value:

        This value violates the general contract of Object.equals(java.lang.Object) by returning true when compared to null. Its toString() method returns "null".

    • Constructor Detail

      • JSONObject

        public JSONObject()
        Creates a JSONObject with no name/value mappings.
      • JSONObject

        public JSONObject(Map copyFrom)
        Creates a new JSONObject by copying all name/value mappings from the given map.
        Parameters:
        copyFrom - a map whose keys are of type String and whose values are of supported types.
        Throws:
        NullPointerException - if any of the map's keys are null.
      • JSONObject

        public JSONObject(JSONTokener readFrom)
                   throws JSONException
        Creates a new JSONObject with name/value mappings from the next object in the tokener.
        Parameters:
        readFrom - a tokener whose nextValue() method will yield a JSONObject.
        Throws:
        JSONException - if the parse fails or doesn't yield a JSONObject.
      • JSONObject

        public JSONObject(String json)
                   throws JSONException
        Creates a new JSONObject with name/value mappings from the JSON string.
        Parameters:
        json - a JSON-encoded string containing an object.
        Throws:
        JSONException - if the parse fails or doesn't yield a JSONObject.
      • JSONObject

        public JSONObject(JSONObject copyFrom,
                  String[] names)
                   throws JSONException
        Creates a new JSONObject by copying mappings for the listed names from the given object. Names that aren't present in copyFrom will be skipped.
        Throws:
        JSONException
    • Method Detail

      • length

        public int length()
        Returns the number of name/value mappings in this object.
      • accumulate

        public JSONObject accumulate(String name,
                            Object value)
                              throws JSONException
        Appends value to the array already mapped to name. If this object has no mapping for name, this inserts a new mapping. If the mapping exists but its value is not an array, the existing and new values are inserted in order into a new array which is itself mapped to name. In aggregate, this allows values to be added to a mapping one at a time.
        Parameters:
        value - a JSONObject, JSONArray, String, Boolean, Integer, Long, Double, NULL or null. May not be NaNs or infinities.
        Throws:
        JSONException
      • remove

        public Object remove(String name)
        Removes the named mapping if it exists; does nothing otherwise.
        Returns:
        the value previously mapped by name, or null if there was no such mapping.
      • isNull

        public boolean isNull(String name)
        Returns true if this object has no mapping for name or if it has a mapping whose value is NULL.
      • has

        public boolean has(String name)
        Returns true if this object has a mapping for name. The mapping may be NULL.
      • opt

        public Object opt(String name)
        Returns the value mapped by name, or null if no such mapping exists.
      • getBoolean

        public boolean getBoolean(String name)
                           throws JSONException
        Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean.
        Throws:
        JSONException - if the mapping doesn't exist or cannot be coerced to a boolean.
      • optBoolean

        public boolean optBoolean(String name)
        Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean. Returns false otherwise.
      • optBoolean

        public boolean optBoolean(String name,
                         boolean fallback)
        Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean. Returns fallback otherwise.
      • getDouble

        public double getDouble(String name)
                         throws JSONException
        Returns the value mapped by name if it exists and is a double or can be coerced to a double.
        Throws:
        JSONException - if the mapping doesn't exist or cannot be coerced to a double.
      • optDouble

        public double optDouble(String name)
        Returns the value mapped by name if it exists and is a double or can be coerced to a double. Returns NaN otherwise.
      • optDouble

        public double optDouble(String name,
                       double fallback)
        Returns the value mapped by name if it exists and is a double or can be coerced to a double. Returns fallback otherwise.
      • getInt

        public int getInt(String name)
                   throws JSONException
        Returns the value mapped by name if it exists and is an int or can be coerced to an int.
        Throws:
        JSONException - if the mapping doesn't exist or cannot be coerced to an int.
      • optInt

        public int optInt(String name)
        Returns the value mapped by name if it exists and is an int or can be coerced to an int. Returns 0 otherwise.
      • optInt

        public int optInt(String name,
                 int fallback)
        Returns the value mapped by name if it exists and is an int or can be coerced to an int. Returns fallback otherwise.
      • getLong

        public long getLong(String name)
                     throws JSONException
        Returns the value mapped by name if it exists and is a long or can be coerced to a long.
        Throws:
        JSONException - if the mapping doesn't exist or cannot be coerced to a long.
      • optLong

        public long optLong(String name)
        Returns the value mapped by name if it exists and is a long or can be coerced to a long. Returns 0 otherwise.
      • optLong

        public long optLong(String name,
                   long fallback)
        Returns the value mapped by name if it exists and is a long or can be coerced to a long. Returns fallback otherwise.
      • getString

        public String getString(String name)
                         throws JSONException
        Returns the value mapped by name if it exists, coercing it if necessary.
        Throws:
        JSONException - if no such mapping exists.
      • optString

        public String optString(String name)
        Returns the value mapped by name if it exists, coercing it if necessary. Returns the empty string if no such mapping exists.
      • optString

        public String optString(String name,
                       String fallback)
        Returns the value mapped by name if it exists, coercing it if necessary. Returns fallback if no such mapping exists.
      • getJSONArray

        public JSONArray getJSONArray(String name)
                               throws JSONException
        Returns the value mapped by name if it exists and is a JSONArray.
        Throws:
        JSONException - if the mapping doesn't exist or is not a JSONArray.
      • optJSONArray

        public JSONArray optJSONArray(String name)
        Returns the value mapped by name if it exists and is a JSONArray. Returns null otherwise.
      • getJSONObject

        public JSONObject getJSONObject(String name)
                                 throws JSONException
        Returns the value mapped by name if it exists and is a JSONObject.
        Throws:
        JSONException - if the mapping doesn't exist or is not a JSONObject.
      • optJSONObject

        public JSONObject optJSONObject(String name)
        Returns the value mapped by name if it exists and is a JSONObject. Returns null otherwise.
      • toJSONArray

        public JSONArray toJSONArray(JSONArray names)
                              throws JSONException
        Returns an array with the values corresponding to names. The array contains null for names that aren't mapped. This method returns null if names is either null or empty.
        Throws:
        JSONException
      • keys

        public Iterator keys()
        Returns an iterator of the String names in this object. The returned iterator supports remove, which will remove the corresponding mapping from this object. If this object is modified after the iterator is returned, the iterator's behavior is undefined. The order of the keys is undefined.
      • names

        public JSONArray names()
        Returns an array containing the string names in this object. This method returns null if this object contains no mappings.
      • toString

        public String toString()
        Encodes this object as a compact JSON string, such as:
        {"query":"Pizza","locations":[94043,90210]}
        Overrides:
        toString in class Object
        Returns:
        a printable representation of this object.
      • toString

        public String toString(int indentSpaces)
                        throws JSONException
        Encodes this object as a human readable JSON string for debugging, such as:
         {
             "query": "Pizza",
             "locations": [
                 94043,
                 90210
             ]
         }
        Parameters:
        indentSpaces - the number of spaces to indent for each level of nesting.
        Throws:
        JSONException
      • quote

        public static String quote(String data)
        Encodes data as a JSON string. This applies quotes and any necessary character escaping.
        Parameters:
        data - the string to encode. Null will be interpreted as an empty string.


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