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.
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.
Summary
Fields |
public
static
final
Object |
NULL
A sentinel value used to explicitly define a name with no value.
|
Public constructors |
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 methods |
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 methods |
From
class
java.lang.Object
Object
|
clone()
Creates and returns a copy of this object.
|
boolean
|
equals(Object obj)
Indicates whether some other object is "equal to" this one.
|
void
|
finalize()
Called by the garbage collector on an object when garbage collection
determines that there are no more references to the object.
|
final
Class<?>
|
getClass()
Returns the runtime class of this Object .
|
int
|
hashCode()
Returns a hash code value for the object.
|
final
void
|
notify()
Wakes up a single thread that is waiting on this object's
monitor.
|
final
void
|
notifyAll()
Wakes up all threads that are waiting on this object's monitor.
|
String
|
toString()
Returns a string representation of the object.
|
final
void
|
wait(long millis, int nanos)
Causes the current thread to wait until another thread invokes the
notify() method or the
notifyAll() method for this object, or
some other thread interrupts the current thread, or a certain
amount of real time has elapsed.
|
final
void
|
wait(long millis)
Causes the current thread to wait until either another thread invokes the
notify() method or the
notifyAll() method for this object, or a
specified amount of time has elapsed.
|
final
void
|
wait()
Causes the current thread to wait until another thread invokes the
notify() method or the
notifyAll() method for this object.
|
|
Fields
NULL
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 equals(Object)
by
returning true when compared to null
. Its toString()
method returns "null".
Public constructors
JSONObject
JSONObject ()
Creates a JSONObject
with no name/value mappings.
JSONObject
JSONObject (Map copyFrom)
Creates a new JSONObject
by copying all name/value mappings from
the given map.
Parameters |
copyFrom |
Map :
a map whose keys are of type String and whose
values are of supported types. |
JSONObject
JSONObject (JSONTokener readFrom)
Creates a new JSONObject
with name/value mappings from the next
object in the tokener.
Parameters |
readFrom |
JSONTokener :
a tokener whose nextValue() method will yield a
JSONObject . |
Throws |
JSONException |
if the parse fails or doesn't yield a
JSONObject .
|
JSONObject
JSONObject (String json)
Creates a new JSONObject
with name/value mappings from the JSON
string.
Parameters |
json |
String :
a JSON-encoded string containing an object. |
Throws |
JSONException |
if the parse fails or doesn't yield a JSONObject .
|
JSONObject
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 |
JSONObject
|
names |
String
|
Public methods
accumulate
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.
get
Object get (String name)
Returns the value mapped by name
, or throws if no such mapping exists.
getBoolean
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.
Throws |
JSONException |
if the mapping doesn't exist or cannot be coerced
to a boolean.
|
getDouble
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.
Throws |
JSONException |
if the mapping doesn't exist or cannot be coerced
to a double.
|
getInt
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.
Throws |
JSONException |
if the mapping doesn't exist or cannot be coerced
to an int.
|
getJSONArray
JSONArray getJSONArray (String name)
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 .
|
getJSONObject
JSONObject getJSONObject (String name)
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 .
|
getLong
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.
Throws |
JSONException |
if the mapping doesn't exist or cannot be coerced
to a long.
|
getString
String getString (String name)
Returns the value mapped by name
if it exists, coercing it if
necessary, or throws if no such mapping exists.
has
boolean has (String name)
Returns true if this object has a mapping for name
. The mapping
may be NULL
.
isNull
boolean isNull (String name)
Returns true if this object has no mapping for name
or if it has
a mapping whose value is NULL
.
keys
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.
length
int length ()
Returns the number of name/value mappings in this object.
names
JSONArray names ()
Returns an array containing the string names in this object. This method
returns null if this object contains no mappings.
numberToString
String numberToString (Number number)
Encodes the number as a JSON string.
Parameters |
number |
Number :
a finite value. May not be NaNs or
infinities .
|
opt
Object opt (String name)
Returns the value mapped by name
, or null if no such mapping
exists.
optBoolean
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 |
String
|
fallback |
boolean
|
optBoolean
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.
optDouble
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 |
String
|
fallback |
double
|
optDouble
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.
optInt
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 |
String
|
fallback |
int
|
optInt
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.
optJSONArray
JSONArray optJSONArray (String name)
Returns the value mapped by name
if it exists and is a JSONArray
, or null otherwise.
optJSONObject
JSONObject optJSONObject (String name)
Returns the value mapped by name
if it exists and is a JSONObject
, or null otherwise.
optLong
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.
optLong
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 |
String
|
fallback |
long
|
optString
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 |
String
|
fallback |
String
|
optString
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.
put
JSONObject put (String name,
double value)
Maps name
to value
, clobbering any existing name/value
mapping with the same name.
Parameters |
name |
String
|
value |
double :
a finite value. May not be NaNs or
infinities . |
put
JSONObject put (String name,
boolean value)
Maps name
to value
, clobbering any existing name/value
mapping with the same name.
Parameters |
name |
String
|
value |
boolean
|
put
JSONObject put (String name,
int value)
Maps name
to value
, clobbering any existing name/value
mapping with the same name.
Parameters |
name |
String
|
value |
int
|
put
JSONObject put (String name,
long value)
Maps name
to value
, clobbering any existing name/value
mapping with the same name.
Parameters |
name |
String
|
value |
long
|
put
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.
putOpt
JSONObject putOpt (String name,
Object value)
Equivalent to put(name, value)
when both parameters are non-null;
does nothing otherwise.
Parameters |
name |
String
|
value |
Object
|
quote
String quote (String data)
Encodes data
as a JSON string. This applies quotes and any
necessary character escaping.
Parameters |
data |
String :
the string to encode. Null will be interpreted as an empty
string.
|
remove
Object remove (String name)
Removes the named mapping if it exists; does nothing otherwise.
Returns |
Object |
the value previously mapped by name , or null if there was
no such mapping.
|
toJSONArray
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 |
JSONArray
|
toString
String toString ()
Encodes this object as a compact JSON string, such as:
{"query":"Pizza","locations":[94043,90210]}
Returns |
String |
a string representation of the object.
|
toString
String toString (int indentSpaces)
Encodes this object as a human readable JSON string for debugging, such
as:
{
"query": "Pizza",
"locations": [
94043,
90210
]
}
Parameters |
indentSpaces |
int :
the number of spaces to indent for each level of
nesting.
|
wrap
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.