Class JSONObject
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.
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Field Summary
Fields -
Constructor Summary
ConstructorsConstructorDescriptionCreates aJSONObject
with no name/value mappings.JSONObject
(String json) Creates a newJSONObject
with name/value mappings from the JSON string.JSONObject
(Map copyFrom) Creates a newJSONObject
by copying all name/value mappings from the given map.JSONObject
(JSONObject copyFrom, String[] names) Creates a newJSONObject
by copying mappings for the listed names from the given object.JSONObject
(JSONTokener readFrom) Creates a newJSONObject
with name/value mappings from the next object in the tokener. -
Method Summary
Modifier and TypeMethodDescriptionaccumulate
(String name, Object value) Appendsvalue
to the array already mapped toname
.Appends values to the array mapped toname
.Returns the value mapped byname
, or throws if no such mapping exists.boolean
getBoolean
(String name) Returns the value mapped byname
if it exists and is a boolean or can be coerced to a boolean, or throws otherwise.double
Returns the value mapped byname
if it exists and is a double or can be coerced to a double, or throws otherwise.int
Returns the value mapped byname
if it exists and is an int or can be coerced to an int, or throws otherwise.getJSONArray
(String name) Returns the value mapped byname
if it exists and is aJSONArray
, or throws otherwise.getJSONObject
(String name) Returns the value mapped byname
if it exists and is aJSONObject
, or throws otherwise.long
Returns the value mapped byname
if it exists and is a long or can be coerced to a long, or throws otherwise.Returns the value mapped byname
if it exists, coercing it if necessary, or throws if no such mapping exists.boolean
Returns true if this object has a mapping forname
.boolean
Returns true if this object has no mapping forname
or if it has a mapping whose value isNULL
.keys()
Returns an iterator of theString
names in this object.keySet()
Returns the set ofString
names in this object.int
length()
Returns the number of name/value mappings in this object.names()
Returns an array containing the string names in this object.static String
numberToString
(Number number) Encodes the number as a JSON string.Returns the value mapped byname
, or null if no such mapping exists.boolean
optBoolean
(String name) Returns the value mapped byname
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 byname
if it exists and is a boolean or can be coerced to a boolean, orfallback
otherwise.double
Returns the value mapped byname
if it exists and is a double or can be coerced to a double, orNaN
otherwise.double
Returns the value mapped byname
if it exists and is a double or can be coerced to a double, orfallback
otherwise.int
Returns the value mapped byname
if it exists and is an int or can be coerced to an int, or 0 otherwise.int
Returns the value mapped byname
if it exists and is an int or can be coerced to an int, orfallback
otherwise.optJSONArray
(String name) Returns the value mapped byname
if it exists and is aJSONArray
, or null otherwise.optJSONObject
(String name) Returns the value mapped byname
if it exists and is aJSONObject
, or null otherwise.long
Returns the value mapped byname
if it exists and is a long or can be coerced to a long, or 0 otherwise.long
Returns the value mapped byname
if it exists and is a long or can be coerced to a long, orfallback
otherwise.Returns the value mapped byname
if it exists, coercing it if necessary, or the empty string if no such mapping exists.Returns the value mapped byname
if it exists, coercing it if necessary, orfallback
if no such mapping exists.Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.Equivalent toput(name, value)
when both parameters are non-null; does nothing otherwise.static String
Encodesdata
as a JSON string.Removes the named mapping if it exists; does nothing otherwise.toJSONArray
(JSONArray names) Returns an array with the values corresponding tonames
.toString()
Encodes this object as a compact JSON string, such as:toString
(int indentSpaces) Encodes this object as a human readable JSON string for debugging, such as:static Object
Wraps the given object if necessary.
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Field Details
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NULL
A sentinel value used to explicitly define a name with no value. Unlikenull
, 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(java.lang.Object)
by returning true when compared tonull
. ItstoString()
method returns "null". - show up in the
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Constructor Details
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JSONObject
public JSONObject()Creates aJSONObject
with no name/value mappings. -
JSONObject
Creates a newJSONObject
by copying all name/value mappings from the given map.- Parameters:
copyFrom
- a map whose keys are of typeString
and whose values are of supported types.- Throws:
NullPointerException
- if any of the map's keys are null.
-
JSONObject
Creates a newJSONObject
with name/value mappings from the next object in the tokener.- Parameters:
readFrom
- a tokener whose nextValue() method will yield aJSONObject
.- Throws:
JSONException
- if the parse fails or doesn't yield aJSONObject
.
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JSONObject
Creates a newJSONObject
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 aJSONObject
.
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JSONObject
Creates a newJSONObject
by copying mappings for the listed names from the given object. Names that aren't present incopyFrom
will be skipped.- Throws:
JSONException
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Method Details
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length
public int length()Returns the number of name/value mappings in this object. -
put
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.- Returns:
- this object.
- Throws:
JSONException
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put
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.- Parameters:
value
- a finite value. May not beNaNs
orinfinities
.- Returns:
- this object.
- Throws:
JSONException
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put
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.- Returns:
- this object.
- Throws:
JSONException
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put
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.- Returns:
- this object.
- Throws:
JSONException
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put
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name. If the value isnull
, any existing mapping forname
is removed.- Parameters:
value
- aJSONObject
,JSONArray
, String, Boolean, Integer, Long, Double,NULL
, ornull
. May not beNaNs
orinfinities
.- Returns:
- this object.
- Throws:
JSONException
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putOpt
@NonNull public JSONObject putOpt(@Nullable String name, @Nullable Object value) throws JSONException Equivalent toput(name, value)
when both parameters are non-null; does nothing otherwise.- Throws:
JSONException
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accumulate
@NonNull public JSONObject accumulate(@NonNull String name, @Nullable Object value) throws JSONException Appendsvalue
to the array already mapped toname
. If this object has no mapping forname
, 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 toname
. 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 forname
will always be aJSONArray
. Usingaccumulate
will result in either aJSONArray
or a mapping whose type is the type ofvalue
depending on the number of calls to it.- Parameters:
value
- aJSONObject
,JSONArray
, String, Boolean, Integer, Long, Double,NULL
or null. May not beNaNs
orinfinities
.- Throws:
JSONException
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append
Appends values to the array mapped toname
. A newJSONArray
mapping forname
will be inserted if no mapping exists. If the existing mapping forname
is not aJSONArray
, aJSONException
will be thrown.- Throws:
JSONException
- ifname
isnull
or if the mapping forname
is non-null and is not aJSONArray
.
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remove
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.
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isNull
Returns true if this object has no mapping forname
or if it has a mapping whose value isNULL
. -
has
Returns true if this object has a mapping forname
. The mapping may beNULL
. -
get
Returns the value mapped byname
, or throws if no such mapping exists.- Throws:
JSONException
- if no such mapping exists.
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opt
Returns the value mapped byname
, or null if no such mapping exists. -
getBoolean
Returns the value mapped byname
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.
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optBoolean
Returns the value mapped byname
if it exists and is a boolean or can be coerced to a boolean, or false otherwise. -
optBoolean
Returns the value mapped byname
if it exists and is a boolean or can be coerced to a boolean, orfallback
otherwise. -
getDouble
Returns the value mapped byname
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.
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optDouble
Returns the value mapped byname
if it exists and is a double or can be coerced to a double, orNaN
otherwise. -
optDouble
Returns the value mapped byname
if it exists and is a double or can be coerced to a double, orfallback
otherwise. -
getInt
Returns the value mapped byname
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.
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optInt
Returns the value mapped byname
if it exists and is an int or can be coerced to an int, or 0 otherwise. -
optInt
Returns the value mapped byname
if it exists and is an int or can be coerced to an int, orfallback
otherwise. -
getLong
Returns the value mapped byname
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.
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optLong
Returns the value mapped byname
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
Returns the value mapped byname
if it exists and is a long or can be coerced to a long, orfallback
otherwise. Note that JSON represents numbers as doubles, so this is lossy; use strings to transfer numbers via JSON. -
getString
Returns the value mapped byname
if it exists, coercing it if necessary, or throws if no such mapping exists.- Throws:
JSONException
- if no such mapping exists.
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optString
Returns the value mapped byname
if it exists, coercing it if necessary, or the empty string if no such mapping exists. -
optString
Returns the value mapped byname
if it exists, coercing it if necessary, orfallback
if no such mapping exists. -
getJSONArray
Returns the value mapped byname
if it exists and is aJSONArray
, or throws otherwise.- Throws:
JSONException
- if the mapping doesn't exist or is not aJSONArray
.
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optJSONArray
Returns the value mapped byname
if it exists and is aJSONArray
, or null otherwise. -
getJSONObject
Returns the value mapped byname
if it exists and is aJSONObject
, or throws otherwise.- Throws:
JSONException
- if the mapping doesn't exist or is not aJSONObject
.
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optJSONObject
Returns the value mapped byname
if it exists and is aJSONObject
, or null otherwise. -
toJSONArray
Returns an array with the values corresponding tonames
. The array contains null for names that aren't mapped. This method returns null ifnames
is either null or empty.- Throws:
JSONException
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keys
Returns an iterator of theString
names in this object. The returned iterator supportsremove
, 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
Returns the set ofString
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
Returns an array containing the string names in this object. This method returns null if this object contains no mappings. -
toString
Encodes this object as a compact JSON string, such as:{"query":"Pizza","locations":[94043,90210]}
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toString
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
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numberToString
Encodes the number as a JSON string.- Parameters:
number
- a finite value. May not beNaNs
orinfinities
.- Throws:
JSONException
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quote
Encodesdata
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.
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wrap
Wraps the given object if necessary.If the object is null or , returns
NULL
. If the object is aJSONArray
orJSONObject
, no wrapping is necessary. If the object isNULL
, no wrapping is necessary. If the object is an array orCollection
, returns an equivalentJSONArray
. If the object is aMap
, returns an equivalentJSONObject
. If the object is a primitive wrapper type orString
, returns the object. Otherwise if the object is from ajava
package, returns the result oftoString
. If wrapping fails, returns null.
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