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

public static final Object NULL A sentinel value used to explicitly define a name with no value.

Public Constructor Summary

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

Public Method Summary

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`, or throws if no such mapping exists.
boolean	getBoolean(String name) Returns the value mapped by `name` if it exists and is a boolean or can be coerced to a boolean, or throws otherwise.
double	getDouble(String name) Returns the value mapped by `name` if it exists and is a double or can be coerced to a double, or throws otherwise.
int	getInt(String name) Returns the value mapped by `name` if it exists and is an int or can be coerced to an int, or throws otherwise.
JSONArray	getJSONArray(String name) Returns the value mapped by `name` if it exists and is a `JSONArray`, or throws otherwise.
JSONObject	getJSONObject(String name) Returns the value mapped by `name` if it exists and is a `JSONObject`, or throws otherwise.
long	getLong(String name) Returns the value mapped by `name` if it exists and is a long or can be coerced to a long, or throws otherwise.
String	getString(String name) Returns the value mapped by `name` if it exists, coercing it if necessary, or throws if no such mapping exists.
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<String>	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, boolean fallback) Returns the value mapped by `name` if it exists and is a boolean or can be coerced to a boolean, or `fallback` otherwise.
boolean	optBoolean(String name) Returns the value mapped by `name` if it exists and is a boolean or can be coerced to a boolean, or false otherwise.
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, or `fallback` otherwise.
double	optDouble(String name) Returns the value mapped by `name` if it exists and is a double or can be coerced to a double, or `NaN` otherwise.
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, or `fallback` otherwise.
int	optInt(String name) Returns the value mapped by `name` if it exists and is an int or can be coerced to an int, or 0 otherwise.
JSONArray	optJSONArray(String name) Returns the value mapped by `name` if it exists and is a `JSONArray`, or null otherwise.
JSONObject	optJSONObject(String name) Returns the value mapped by `name` if it exists and is a `JSONObject`, or null otherwise.
long	optLong(String name) Returns the value mapped by `name` if it exists and is a long or can be coerced to a long, or 0 otherwise.
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, or `fallback` otherwise.
String	optString(String name, String fallback) Returns the value mapped by `name` if it exists, coercing it if necessary, or `fallback` if no such mapping exists.
String	optString(String name) Returns the value mapped by `name` if it exists, coercing it if necessary, or the empty string if no such mapping exists.
JSONObject	put(String name, double value) Maps `name` to `value`, clobbering any existing name/value mapping with the same name.
JSONObject	put(String name, boolean 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: {"query":"Pizza","locations":[94043,90210]}
String	toString(int indentSpaces) Encodes this object as a human readable JSON string for debugging, such as: { "query": "Pizza", "locations": [ 94043, 90210 ] }
static Object	wrap(Object o) Wraps the given object if necessary.

Inherited Method Summary

From class java.lang.Object

Object	clone()
boolean	equals(Object arg0)
void	finalize()
final Class<?>	getClass()
int	hashCode()
final void	notify()
final void	notifyAll()
String	toString()
final void	wait(long arg0, int arg1)
final void	wait(long arg0)
final void	wait()

Fields

public static final Object NULL

A sentinel value used to explicitly define a name with no value. Unlike null, names with this value:

show up in the names() array
show up in the keys() iterator
return true for has(String)
do not throw on get(String)
are included in the encoded JSON string.

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

Public Constructors

public JSONObject ()

Creates a JSONObject with no name/value mappings.

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.

public JSONObject (JSONTokener readFrom)

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`.

public JSONObject (String json)

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`.

public JSONObject (JSONObject copyFrom, String[] names)

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.

Parameters

copyFrom
names

Throws

JSONException

Public Methods

public JSONObject accumulate (String name, Object value)

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.

Note that append(String, Object) provides better semantics. In particular, the mapping for name will always be a JSONArray. Using accumulate will result in either a JSONArray or a mapping whose type is the type of value depending on the number of calls to it.

Parameters

name
value	a `JSONObject`, `JSONArray`, String, Boolean, Integer, Long, Double, `NULL` or null. May not be `NaNs` or `infinities`.

Throws

JSONException

public Object get (String name)

Returns the value mapped by name, or throws if no such mapping exists.

Parameters

name

Throws

JSONException	if no such mapping exists.

public boolean getBoolean (String name)

Returns the value mapped by name if it exists and is a boolean or can be coerced to a boolean, or throws otherwise.

Parameters

name

Throws

JSONException	if the mapping doesn't exist or cannot be coerced to a boolean.

public double getDouble (String name)

Returns the value mapped by name if it exists and is a double or can be coerced to a double, or throws otherwise.

Parameters

name

Throws

JSONException	if the mapping doesn't exist or cannot be coerced to a double.

public int getInt (String name)

Returns the value mapped by name if it exists and is an int or can be coerced to an int, or throws otherwise.

Parameters

name

Throws

JSONException	if the mapping doesn't exist or cannot be coerced to an int.

public JSONArray getJSONArray (String name)

Returns the value mapped by name if it exists and is a JSONArray, or throws otherwise.

Parameters

name

Throws

JSONException	if the mapping doesn't exist or is not a `JSONArray`.

public JSONObject getJSONObject (String name)

Returns the value mapped by name if it exists and is a JSONObject, or throws otherwise.

Parameters

name

Throws

JSONException	if the mapping doesn't exist or is not a `JSONObject`.

public long getLong (String name)

Returns the value mapped by name if it exists and is a long or can be coerced to a long, or throws otherwise. Note that JSON represents numbers as doubles, so this is lossy; use strings to transfer numbers via JSON.

Parameters

name

Throws

JSONException	if the mapping doesn't exist or cannot be coerced to a long.

public String getString (String name)

Returns the value mapped by name if it exists, coercing it if necessary, or throws if no such mapping exists.

Parameters

name

Throws

JSONException	if no such mapping exists.

public boolean has (String name)

Returns true if this object has a mapping for name. The mapping may be NULL.

Parameters

name

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.

Parameters

name

public Iterator<String> 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.

public int length ()

Returns the number of name/value mappings in this object.

public JSONArray names ()

Returns an array containing the string names in this object. This method returns null if this object contains no mappings.

public static String numberToString (Number number)

Encodes the number as a JSON string.

Parameters

number	a finite value. May not be `NaNs` or `infinities`.

Throws

JSONException

public Object opt (String name)

Returns the value mapped by name, or null if no such mapping exists.

Parameters

name

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, or fallback otherwise.

Parameters

name
fallback

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, or false otherwise.

Parameters

name

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, or fallback otherwise.

Parameters

name
fallback

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, or NaN otherwise.

Parameters

name

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, or fallback otherwise.

Parameters

name
fallback

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, or 0 otherwise.

Parameters

name

public JSONArray optJSONArray (String name)

Returns the value mapped by name if it exists and is a JSONArray, or null otherwise.

Parameters

name

public JSONObject optJSONObject (String name)

Returns the value mapped by name if it exists and is a JSONObject, or null otherwise.

Parameters

name

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, or 0 otherwise. Note that JSON represents numbers as doubles, so this is lossy; use strings to transfer numbers via JSON.

Parameters

name

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, or fallback otherwise. Note that JSON represents numbers as doubles, so this is lossy; use strings to transfer numbers via JSON.

Parameters

name
fallback

public String optString (String name, String fallback)

Returns the value mapped by name if it exists, coercing it if necessary, or fallback if no such mapping exists.

Parameters

name
fallback

public String optString (String name)

Returns the value mapped by name if it exists, coercing it if necessary, or the empty string if no such mapping exists.

Parameters

name

public JSONObject put (String name, double value)

Maps name to value, clobbering any existing name/value mapping with the same name.

Parameters

name
value	a finite value. May not be `NaNs` or `infinities`.

Returns

this object.

Throws

JSONException

public JSONObject put (String name, boolean value)

Maps name to value, clobbering any existing name/value mapping with the same name.

Parameters

name
value

Returns

this object.

Throws

JSONException

public JSONObject put (String name, int value)

Maps name to value, clobbering any existing name/value mapping with the same name.

Parameters

name
value

Returns

this object.

Throws

JSONException

public JSONObject put (String name, long value)

Maps name to value, clobbering any existing name/value mapping with the same name.

Parameters

name
value

Returns

this object.

Throws

JSONException

public JSONObject put (String name, Object value)

Maps name to value, clobbering any existing name/value mapping with the same name. If the value is null, any existing mapping for name is removed.

Parameters

name
value	a `JSONObject`, `JSONArray`, String, Boolean, Integer, Long, Double, `NULL`, or `null`. May not be `NaNs` or `infinities`.

Returns

this object.

Throws

JSONException

public JSONObject putOpt (String name, Object value)

Equivalent to put(name, value) when both parameters are non-null; does nothing otherwise.

Parameters

name
value

Throws

JSONException

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.

public Object remove (String name)

Removes the named mapping if it exists; does nothing otherwise.

Parameters

name

Returns

the value previously mapped by name, or null if there was no such mapping.

public JSONArray toJSONArray (JSONArray names)

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.

Parameters

names

Throws

JSONException

public String toString ()

Encodes this object as a compact JSON string, such as:

{"query":"Pizza","locations":[94043,90210]}

public String toString (int indentSpaces)

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

public static Object wrap (Object o)

Wraps the given object if necessary.

If the object is null or , returns NULL. If the object is a JSONArray or JSONObject, no wrapping is necessary. If the object is NULL, no wrapping is necessary. If the object is an array or Collection, returns an equivalent JSONArray. If the object is a Map, returns an equivalent JSONObject. If the object is a primitive wrapper type or String, returns the object. Otherwise if the object is from a java package, returns the result of toString. If wrapping fails, returns null.

Parameters

o