Package org.json

Class JSONObject

java.lang.Object

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

Constructor Summary

Constructors

Constructor	Description
JSONObject()	Creates a JSONObject with no name/value mappings.
JSONObject(String json)	Creates a new JSONObject with name/value mappings from the JSON string.
JSONObject(Map copyFrom)	Creates a new JSONObject by copying all name/value mappings from the given map.
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.

Method Summary

Modifier and Type	Method	Description
JSONObject	accumulate(String name, Object value)	Appends value to the array already mapped to name.
JSONObject	append(String name, Object value)	Appends values to the array 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.
Set<String>	keySet()	Returns the set of 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, or false otherwise.
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.
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.
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.
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.
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.
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)	Returns the value mapped by name if it exists, coercing it if necessary, or the empty string if no such mapping exists.
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.
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:
static Object	wrap(Object o)	Wraps the given object if necessary.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Details

NULL

@NonNull
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(java.lang.Object) by returning true when compared to null. Its toString() method returns "null".

Constructor Details

JSONObject

public JSONObject()

Creates a JSONObject with no name/value mappings.

JSONObject

public JSONObject(@NonNull
 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(@NonNull
 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(@NonNull
 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(@NonNull
 JSONObject copyFrom,
 @NonNull
 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 Details

length

public int length()

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

put

@NonNull
public JSONObject put(@NonNull
 String name,
 boolean value)
               throws JSONException

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

Returns:

this object.

Throws:

JSONException

put

@NonNull
public JSONObject put(@NonNull
 String name,
 double value)
               throws JSONException

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

Parameters:

value - a finite value. May not be NaNs or infinities.

Returns:

this object.

Throws:

JSONException

put

@NonNull
public JSONObject put(@NonNull
 String name,
 int value)
               throws JSONException

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

Returns:

this object.

Throws:

JSONException

put

@NonNull
public JSONObject put(@NonNull
 String name,
 long value)
               throws JSONException

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

Returns:

this object.

Throws:

JSONException

put

@NonNull
public JSONObject put(@NonNull
 String name,
 @Nullable
 Object value)
               throws JSONException

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:

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

Returns:

this object.

Throws:

JSONException

putOpt

@NonNull
public JSONObject putOpt(@Nullable
 String name,
 @Nullable
 Object value)
                  throws JSONException

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

Throws:

JSONException

accumulate

@NonNull
public JSONObject accumulate(@NonNull
 String name,
 @Nullable
 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.

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:

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

Throws:

JSONException

append

public JSONObject append(String name,
 Object value)
                  throws JSONException

Appends values to the array mapped to name. A new JSONArray mapping for name will be inserted if no mapping exists. If the existing mapping for name is not a JSONArray, a JSONException will be thrown.

Throws:

JSONException - if name is null or if the mapping for name is non-null and is not a JSONArray.

remove

@Nullable
public Object remove(@Nullable
 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(@Nullable
 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(@Nullable
 String name)

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

get

@NonNull
public Object get(@NonNull
 String name)
           throws JSONException

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

Throws:

JSONException - if no such mapping exists.

opt

@Nullable
public Object opt(@Nullable
 String name)

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

getBoolean

public boolean getBoolean(@NonNull
 String name)
                   throws JSONException

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

Throws:

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

optBoolean

public boolean optBoolean(@Nullable
 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.

optBoolean

public boolean optBoolean(@Nullable
 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.

getDouble

public double getDouble(@NonNull
 String name)
                 throws JSONException

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

Throws:

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

optDouble

public double optDouble(@Nullable
 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.

optDouble

public double optDouble(@Nullable
 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.

getInt

public int getInt(@NonNull
 String name)
           throws JSONException

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

Throws:

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

optInt

public int optInt(@Nullable
 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.

optInt

public int optInt(@Nullable
 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.

getLong

public long getLong(@NonNull
 String name)
             throws JSONException

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.

Throws:

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

optLong

public long optLong(@Nullable
 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.

optLong

public long optLong(@Nullable
 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.

getString

@NonNull
public String getString(@NonNull
 String name)
                 throws JSONException

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

Throws:

JSONException - if no such mapping exists.

optString

@NonNull
public String optString(@Nullable
 String name)

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

optString

@NonNull
public String optString(@Nullable
 String name,
 @NonNull
 String fallback)

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

getJSONArray

@NonNull
public JSONArray getJSONArray(@NonNull
 String name)
                       throws JSONException

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

Throws:

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

optJSONArray

@Nullable
public JSONArray optJSONArray(@Nullable
 String name)

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

getJSONObject

@NonNull
public JSONObject getJSONObject(@NonNull
 String name)
                         throws JSONException

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

Throws:

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

optJSONObject

@Nullable
public JSONObject optJSONObject(@Nullable
 String name)

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

toJSONArray

@Nullable
public JSONArray toJSONArray(@Nullable
 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

@NonNull
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.

keySet

public Set<String> keySet()

Returns the set of String names in this object. The returned set is a view of the keys in this object. Set.remove(Object) will remove the corresponding mapping from this object and set iterator behaviour is undefined if this object is modified after it is returned.

See keys().

names

@Nullable
public JSONArray names()

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

toString

@NonNull
public String toString()

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

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

Overrides:

toString in class Object

toString

@NonNull
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

numberToString

@NonNull
public static String numberToString(@NonNull
 Number number)
                             throws JSONException

Encodes the number as a JSON string.

Parameters:

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

Throws:

JSONException

quote

@NonNull
public static String quote(@Nullable
 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.

wrap

@Nullable
public static Object wrap(@Nullable
 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.