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 usingdoubleValue
. Strings that can be coerced usingDouble.valueOf(String)
will be. - When the requested type is an int, other
Number
types will be coerced usingintValue
. Strings that can be coerced usingDouble.valueOf(String)
will be, and then cast to int. - When the requested type is a long, other
Number
types will be coerced usinglongValue
. Strings that can be coerced usingDouble.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 valueNULL
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 aJSONException
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 | |
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 | |
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
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
forhas(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 |
---|