public class

JSONObject

extends Object
java.lang.Object
   ↳ org.json.JSONObject

Class Overview

A JSONObject is an unordered collection of name/value pairs. Its external form is a string wrapped in curly braces with colons between the names and values, and commas between the values and names. The internal form is an object having get and opt methods for accessing the values by name, and put methods for adding or replacing values by name. The values can be any of these types: Boolean, JSONArray, JSONObject, Number, String, or the JSONObject.NULL object. A JSONObject constructor can be used to convert an external form JSON text into an internal form whose values can be retrieved with the get and opt methods, or to convert values into a JSON text using the put and toString methods. A get method returns a value if one can be found, and throws an exception if one cannot be found. An opt method returns a default value instead of throwing an exception, and so is useful for obtaining optional values.

The generic get() and opt() methods return an object, which you can cast or query for type. There are also typed get and opt methods that do type checking and type coersion for you.

The put methods adds values to an object. For example, 

     myString = new JSONObject().put("JSON", "Hello, World!").toString();
produces the string {"JSON": "Hello, World"}.

The texts produced by the toString methods strictly conform to the JSON sysntax rules. The constructors are more forgiving in the texts they will accept:

  • An extra , (comma) may appear just before the closing brace.
  • Strings may be quoted with ' (single quote).
  • Strings do not need to be quoted at all if they do not begin with a quote or single quote, and if they do not contain leading or trailing spaces, and if they do not contain any of these characters: { } [ ] / \ : , = ; # and if they do not look like numbers and if they are not the reserved words true, false, or null.
  • Keys can be followed by = or => as well as by :.
  • Values can be followed by ; (semicolon) as well as by , (comma).
  • Numbers may have the 0- (octal) or 0x- (hex) prefix.
  • Comments written in the slashshlash, slashstar, and hash conventions will be ignored.

Summary

Constants
Object NULL It is sometimes more convenient and less ambiguous to have a NULL object than to use Java's null value.
Public Constructors
JSONObject()
Construct an empty JSONObject.
JSONObject(JSONObject jo, String[] sa)
Construct a JSONObject from a subset of another JSONObject.
JSONObject(JSONTokener x)
Construct a JSONObject from a JSONTokener.
JSONObject(Map map)
Construct a JSONObject from a Map.
JSONObject(String string)
Construct a JSONObject from a string.
Public Methods
JSONObject accumulate(String key, Object value)
Accumulate values under a key.
Object get(String key)
Get the value object associated with a key.
boolean getBoolean(String key)
Get the boolean value associated with a key.
double getDouble(String key)
Get the double value associated with a key.
int getInt(String key)
Get the int value associated with a key.
JSONArray getJSONArray(String key)
Get the JSONArray value associated with a key.
JSONObject getJSONObject(String key)
Get the JSONObject value associated with a key.
long getLong(String key)
Get the long value associated with a key.
String getString(String key)
Get the string associated with a key.
boolean has(String key)
Determine if the JSONObject contains a specific key.
boolean isNull(String key)
Determine if the value associated with the key is null or if there is no value.
Iterator keys()
Get an enumeration of the keys of the JSONObject.
int length()
Get the number of keys stored in the JSONObject.
JSONArray names()
Produce a JSONArray containing the names of the elements of this JSONObject.
static String numberToString(Number n)
Produce a string from a number.
Object opt(String key)
Get an optional value associated with a key.
boolean optBoolean(String key)
Get an optional boolean associated with a key.
boolean optBoolean(String key, boolean defaultValue)
Get an optional boolean associated with a key.
double optDouble(String key)
Get an optional double associated with a key, or NaN if there is no such key or if its value is not a number.
double optDouble(String key, double defaultValue)
Get an optional double associated with a key, or the defaultValue if there is no such key or if its value is not a number.
int optInt(String key, int defaultValue)
Get an optional int value associated with a key, or the default if there is no such key or if the value is not a number.
int optInt(String key)
Get an optional int value associated with a key, or zero if there is no such key or if the value is not a number.
JSONArray optJSONArray(String key)
Get an optional JSONArray associated with a key.
JSONObject optJSONObject(String key)
Get an optional JSONObject associated with a key.
long optLong(String key, long defaultValue)
Get an optional long value associated with a key, or the default if there is no such key or if the value is not a number.
long optLong(String key)
Get an optional long value associated with a key, or zero if there is no such key or if the value is not a number.
String optString(String key, String defaultValue)
Get an optional string associated with a key.
String optString(String key)
Get an optional string associated with a key.
JSONObject put(String key, boolean value)
Put a key/boolean pair in the JSONObject.
JSONObject put(String key, double value)
Put a key/double pair in the JSONObject.
JSONObject put(String key, Object value)
Put a key/value pair in the JSONObject.
JSONObject put(String key, int value)
Put a key/int pair in the JSONObject.
JSONObject put(String key, long value)
Put a key/long pair in the JSONObject.
JSONObject putOpt(String key, Object value)
Put a key/value pair in the JSONObject, but only if the key and the value are both non-null.
static String quote(String string)
Produce a string in double quotes with backslash sequences in all the right places.
Object remove(String key)
Remove a name and its value, if present.
JSONArray toJSONArray(JSONArray names)
Produce a JSONArray containing the values of the members of this JSONObject.
String toString()
Make an JSON text of this JSONObject.
String toString(int indentFactor)
Make a prettyprinted JSON text of this JSONObject.
[Expand]
Inherited Methods
From class java.lang.Object

Constants

public static final Object NULL

It is sometimes more convenient and less ambiguous to have a NULL object than to use Java's null value. JSONObject.NULL.equals(null) returns true. JSONObject.NULL.toString() returns "null".

Public Constructors

public JSONObject ()

Construct an empty JSONObject.

public JSONObject (JSONObject jo, String[] sa)

Construct a JSONObject from a subset of another JSONObject. An array of strings is used to identify the keys that should be copied. Missing keys are ignored.

Parameters
jo A JSONObject.
sa An array of strings.
Throws
JSONException If a value is a non-finite number.

public JSONObject (JSONTokener x)

Construct a JSONObject from a JSONTokener.

Parameters
x A JSONTokener object containing the source string.
Throws
JSONException If there is a syntax error in the source string.

public JSONObject (Map map)

Construct a JSONObject from a Map.

Parameters
map A map object that can be used to initialize the contents of the JSONObject.

public JSONObject (String string)

Construct a JSONObject from a string. This is the most commonly used JSONObject constructor.

Parameters
string A string beginning with { (left brace) and ending with } (right brace).
Throws
JSONException If there is a syntax error in the source string.

Public Methods

public JSONObject accumulate (String key, Object value)

Accumulate values under a key. It is similar to the put method except that if there is already an object stored under the key then a JSONArray is stored under the key to hold all of the accumulated values. If there is already a JSONArray, then the new value is appended to it. In contrast, the put method replaces the previous value.

Parameters
key A key string.
value An object to be accumulated under the key.
Returns
  • this.
Throws
JSONException If the value is an invalid number or if the key is null.

public Object get (String key)

Get the value object associated with a key.

Parameters
key A key string.
Returns
  • The object associated with the key.
Throws
JSONException if the key is not found.

public boolean getBoolean (String key)

Get the boolean value associated with a key.

Parameters
key A key string.
Returns
  • The truth.
Throws
JSONException if the value is not a Boolean or the String "true" or "false".

public double getDouble (String key)

Get the double value associated with a key.

Parameters
key A key string.
Returns
  • The numeric value.
Throws
JSONException if the key is not found or if the value is not a Number object and cannot be converted to a number.

public int getInt (String key)

Get the int value associated with a key. If the number value is too large for an int, it will be clipped.

Parameters
key A key string.
Returns
  • The integer value.
Throws
JSONException if the key is not found or if the value cannot be converted to an integer.

public JSONArray getJSONArray (String key)

Get the JSONArray value associated with a key.

Parameters
key A key string.
Returns
  • A JSONArray which is the value.
Throws
JSONException if the key is not found or if the value is not a JSONArray.

public JSONObject getJSONObject (String key)

Get the JSONObject value associated with a key.

Parameters
key A key string.
Returns
  • A JSONObject which is the value.
Throws
JSONException if the key is not found or if the value is not a JSONObject.

public long getLong (String key)

Get the long value associated with a key. If the number value is too long for a long, it will be clipped.

Parameters
key A key string.
Returns
  • The long value.
Throws
JSONException if the key is not found or if the value cannot be converted to a long.

public String getString (String key)

Get the string associated with a key.

Parameters
key A key string.
Returns
  • A string which is the value.
Throws
JSONException if the key is not found.

public boolean has (String key)

Determine if the JSONObject contains a specific key.

Parameters
key A key string.
Returns
  • true if the key exists in the JSONObject.

public boolean isNull (String key)

Determine if the value associated with the key is null or if there is no value.

Parameters
key A key string.
Returns
  • true if there is no value associated with the key or if the value is the JSONObject.NULL object.

public Iterator keys ()

Get an enumeration of the keys of the JSONObject.

Returns
  • An iterator of the keys.

public int length ()

Get the number of keys stored in the JSONObject.

Returns
  • The number of keys in the JSONObject.

public JSONArray names ()

Produce a JSONArray containing the names of the elements of this JSONObject.

Returns
  • A JSONArray containing the key strings, or null if the JSONObject is empty.

public static String numberToString (Number n)

Produce a string from a number.

Parameters
n A Number
Returns
  • A String.
Throws
JSONException If n is a non-finite number.

public Object opt (String key)

Get an optional value associated with a key.

Parameters
key A key string.
Returns
  • An object which is the value, or null if there is no value.

public boolean optBoolean (String key)

Get an optional boolean associated with a key. It returns false if there is no such key, or if the value is not Boolean.TRUE or the String "true".

Parameters
key A key string.
Returns
  • The truth.

public boolean optBoolean (String key, boolean defaultValue)

Get an optional boolean associated with a key. It returns the defaultValue if there is no such key, or if it is not a Boolean or the String "true" or "false" (case insensitive).

Parameters
key A key string.
defaultValue The default.
Returns
  • The truth.

public double optDouble (String key)

Get an optional double associated with a key, or NaN if there is no such key or if its value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

Parameters
key A string which is the key.
Returns
  • An object which is the value.

public double optDouble (String key, double defaultValue)

Get an optional double associated with a key, or the defaultValue if there is no such key or if its value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

Parameters
key A key string.
defaultValue The default.
Returns
  • An object which is the value.

public int optInt (String key, int defaultValue)

Get an optional int value associated with a key, or the default if there is no such key or if the value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

Parameters
key A key string.
defaultValue The default.
Returns
  • An object which is the value.

public int optInt (String key)

Get an optional int value associated with a key, or zero if there is no such key or if the value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

Parameters
key A key string.
Returns
  • An object which is the value.

public JSONArray optJSONArray (String key)

Get an optional JSONArray associated with a key. It returns null if there is no such key, or if its value is not a JSONArray.

Parameters
key A key string.
Returns
  • A JSONArray which is the value.

public JSONObject optJSONObject (String key)

Get an optional JSONObject associated with a key. It returns null if there is no such key, or if its value is not a JSONObject.

Parameters
key A key string.
Returns
  • A JSONObject which is the value.

public long optLong (String key, long defaultValue)

Get an optional long value associated with a key, or the default if there is no such key or if the value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

Parameters
key A key string.
defaultValue The default.
Returns
  • An object which is the value.

public long optLong (String key)

Get an optional long value associated with a key, or zero if there is no such key or if the value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

Parameters
key A key string.
Returns
  • An object which is the value.

public String optString (String key, String defaultValue)

Get an optional string associated with a key. It returns the defaultValue if there is no such key.

Parameters
key A key string.
defaultValue The default.
Returns
  • A string which is the value.

public String optString (String key)

Get an optional string associated with a key. It returns an empty string if there is no such key. If the value is not a string and is not null, then it is coverted to a string.

Parameters
key A key string.
Returns
  • A string which is the value.

public JSONObject put (String key, boolean value)

Put a key/boolean pair in the JSONObject.

Parameters
key A key string.
value A boolean which is the value.
Returns
  • this.
Throws
JSONException If the key is null.

public JSONObject put (String key, double value)

Put a key/double pair in the JSONObject.

Parameters
key A key string.
value A double which is the value.
Returns
  • this.
Throws
JSONException If the key is null or if the number is invalid.

public JSONObject put (String key, Object value)

Put a key/value pair in the JSONObject. If the value is null, then the key will be removed from the JSONObject if it is present.

Parameters
key A key string.
value An object which is the value. It should be of one of these types: Boolean, Double, Integer, JSONArray, JSONObject, Long, String, or the JSONObject.NULL object.
Returns
  • this.
Throws
JSONException If the value is non-finite number or if the key is null.

public JSONObject put (String key, int value)

Put a key/int pair in the JSONObject.

Parameters
key A key string.
value An int which is the value.
Returns
  • this.
Throws
JSONException If the key is null.

public JSONObject put (String key, long value)

Put a key/long pair in the JSONObject.

Parameters
key A key string.
value A long which is the value.
Returns
  • this.
Throws
JSONException If the key is null.

public JSONObject putOpt (String key, Object value)

Put a key/value pair in the JSONObject, but only if the key and the value are both non-null.

Parameters
key A key string.
value An object which is the value. It should be of one of these types: Boolean, Double, Integer, JSONArray, JSONObject, Long, String, or the JSONObject.NULL object.
Returns
  • this.
Throws
JSONException If the value is a non-finite number.

public static String quote (String string)

Produce a string in double quotes with backslash sequences in all the right places. A backslash will be inserted within </, allowing JSON text to be delivered in HTML. In JSON text, a string cannot contain a control character or an unescaped quote or backslash.

Parameters
string A String
Returns
  • A String correctly formatted for insertion in a JSON text.

public Object remove (String key)

Remove a name and its value, if present.

Parameters
key The name to be removed.
Returns
  • The value that was associated with the name, or null if there was no value.

public JSONArray toJSONArray (JSONArray names)

Produce a JSONArray containing the values of the members of this JSONObject.

Parameters
names A JSONArray containing a list of key strings. This determines the sequence of the values in the result.
Returns
  • A JSONArray of values.
Throws
JSONException If any of the values are non-finite numbers.

public String toString ()

Make an JSON text of this JSONObject. For compactness, no whitespace is added. If this would not result in a syntactically correct JSON text, then null will be returned instead.

Warning: This method assumes that the data structure is acyclical.

Returns
  • a printable, displayable, portable, transmittable representation of the object, beginning with { (left brace) and ending with } (right brace).

public String toString (int indentFactor)

Make a prettyprinted JSON text of this JSONObject.

Warning: This method assumes that the data structure is acyclical.

Parameters
indentFactor The number of spaces to add to each level of indentation.
Returns
  • a printable, displayable, portable, transmittable representation of the object, beginning with { (left brace) and ending with } (right brace).
Throws
JSONException If the object contains an invalid number.