Class JSONObject
- java.lang.Object
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- org.json.JSONObject
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public class JSONObject extends Object
A modifiable set of name/value mappings. Names are unique, non-null strings. Values may be any mix ofJSONObjects
,JSONArrays
, Strings, Booleans, Integers, Longs, Doubles orNULL
. Values may not benull
,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 valueNULL
. In particular, callingput(name, null)
removes the named entry from the object butput(name, JSONObject.NULL)
stores an entry whose value isJSONObject.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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Constructor Summary
Constructors Constructor Description JSONObject()
Creates 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.
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description JSONObject
accumulate(String name, Object value)
Appendsvalue
to the array already mapped toname
.Object
get(String name)
Returns the value mapped byname
.boolean
getBoolean(String name)
Returns the value mapped byname
if it exists and is a boolean or can be coerced to a boolean.double
getDouble(String name)
Returns the value mapped byname
if it exists and is a double or can be coerced to a double.int
getInt(String name)
Returns the value mapped byname
if it exists and is an int or can be coerced to an int.JSONArray
getJSONArray(String name)
Returns the value mapped byname
if it exists and is aJSONArray
.JSONObject
getJSONObject(String name)
Returns the value mapped byname
if it exists and is aJSONObject
.long
getLong(String name)
Returns the value mapped byname
if it exists and is a long or can be coerced to a long.String
getString(String name)
Returns the value mapped byname
if it exists, coercing it if necessary.boolean
has(String name)
Returns true if this object has a mapping forname
.boolean
isNull(String name)
Returns true if this object has no mapping forname
or if it has a mapping whose value isNULL
.Iterator
keys()
Returns an iterator of theString
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 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.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.double
optDouble(String name)
Returns the value mapped byname
if it exists and is a double or can be coerced to a double.double
optDouble(String name, double fallback)
Returns the value mapped byname
if it exists and is a double or can be coerced to a double.int
optInt(String name)
Returns the value mapped byname
if it exists and is an int or can be coerced to an int.int
optInt(String name, int fallback)
Returns the value mapped byname
if it exists and is an int or can be coerced to an int.JSONArray
optJSONArray(String name)
Returns the value mapped byname
if it exists and is aJSONArray
.JSONObject
optJSONObject(String name)
Returns the value mapped byname
if it exists and is aJSONObject
.long
optLong(String name)
Returns the value mapped byname
if it exists and is a long or can be coerced to a long.long
optLong(String name, long fallback)
Returns the value mapped byname
if it exists and is a long or can be coerced to a long.String
optString(String name)
Returns the value mapped byname
if it exists, coercing it if necessary.String
optString(String name, String fallback)
Returns the value mapped byname
if it exists, coercing it if necessary.JSONObject
put(String name, boolean value)
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.JSONObject
put(String name, double value)
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.JSONObject
put(String name, int value)
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.JSONObject
put(String name, long value)
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.JSONObject
put(String name, Object value)
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.JSONObject
putOpt(String name, Object value)
Equivalent toput(name, value)
when both parameters are non-null; does nothing otherwise.static String
quote(String data)
Encodesdata
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 tonames
.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:
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Field Detail
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NULL
public static final Object 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 Detail
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JSONObject
public JSONObject()
Creates aJSONObject
with no name/value mappings.
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JSONObject
public JSONObject(Map copyFrom)
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.
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JSONObject
public JSONObject(JSONTokener readFrom) throws JSONException
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
public JSONObject(String json) throws JSONException
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
public JSONObject(JSONObject copyFrom, String[] names) throws JSONException
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 Detail
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length
public int length()
Returns the number of name/value mappings in this object.
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put
public JSONObject put(String name, boolean value) throws JSONException
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.- Returns:
- this object.
- Throws:
JSONException
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put
public JSONObject put(String name, double value) throws JSONException
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
public JSONObject put(String name, int value) throws JSONException
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.- Returns:
- this object.
- Throws:
JSONException
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put
public JSONObject put(String name, long value) throws JSONException
Mapsname
tovalue
, clobbering any existing name/value mapping with the same name.- Returns:
- this object.
- Throws:
JSONException
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put
public JSONObject put(String name, Object value) throws JSONException
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
public JSONObject putOpt(String name, Object value) throws JSONException
Equivalent toput(name, value)
when both parameters are non-null; does nothing otherwise.- Throws:
JSONException
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accumulate
public JSONObject accumulate(String name, 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.- Parameters:
value
- aJSONObject
,JSONArray
, String, Boolean, Integer, Long, Double,NULL
or null. May not beNaNs
orinfinities
.- Throws:
JSONException
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remove
public Object remove(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.
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isNull
public boolean isNull(String name)
Returns true if this object has no mapping forname
or if it has a mapping whose value isNULL
.
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has
public boolean has(String name)
Returns true if this object has a mapping forname
. The mapping may beNULL
.
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get
public Object get(String name) throws JSONException
Returns the value mapped byname
.- Throws:
JSONException
- if no such mapping exists.
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opt
public Object opt(String name)
Returns the value mapped byname
, or null if no such mapping exists.
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getBoolean
public boolean getBoolean(String name) throws JSONException
Returns the value mapped byname
if it exists and is a boolean or can be coerced to a boolean.- Throws:
JSONException
- if the mapping doesn't exist or cannot be coerced to a boolean.
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optBoolean
public boolean optBoolean(String name)
Returns the value mapped byname
if it exists and is a boolean or can be coerced to a boolean. Returns false otherwise.
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optBoolean
public 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. Returnsfallback
otherwise.
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getDouble
public double getDouble(String name) throws JSONException
Returns the value mapped byname
if it exists and is a double or can be coerced to a double.- Throws:
JSONException
- if the mapping doesn't exist or cannot be coerced to a double.
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optDouble
public double optDouble(String name)
Returns the value mapped byname
if it exists and is a double or can be coerced to a double. ReturnsNaN
otherwise.
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optDouble
public double optDouble(String name, double fallback)
Returns the value mapped byname
if it exists and is a double or can be coerced to a double. Returnsfallback
otherwise.
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getInt
public int getInt(String name) throws JSONException
Returns the value mapped byname
if it exists and is an int or can be coerced to an int.- Throws:
JSONException
- if the mapping doesn't exist or cannot be coerced to an int.
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optInt
public int optInt(String name)
Returns the value mapped byname
if it exists and is an int or can be coerced to an int. Returns 0 otherwise.
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optInt
public int optInt(String name, int fallback)
Returns the value mapped byname
if it exists and is an int or can be coerced to an int. Returnsfallback
otherwise.
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getLong
public long getLong(String name) throws JSONException
Returns the value mapped byname
if it exists and is a long or can be coerced to a long.- Throws:
JSONException
- if the mapping doesn't exist or cannot be coerced to a long.
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optLong
public long optLong(String name)
Returns the value mapped byname
if it exists and is a long or can be coerced to a long. Returns 0 otherwise.
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optLong
public long optLong(String name, long fallback)
Returns the value mapped byname
if it exists and is a long or can be coerced to a long. Returnsfallback
otherwise.
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getString
public String getString(String name) throws JSONException
Returns the value mapped byname
if it exists, coercing it if necessary.- Throws:
JSONException
- if no such mapping exists.
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optString
public String optString(String name)
Returns the value mapped byname
if it exists, coercing it if necessary. Returns the empty string if no such mapping exists.
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optString
public String optString(String name, String fallback)
Returns the value mapped byname
if it exists, coercing it if necessary. Returnsfallback
if no such mapping exists.
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getJSONArray
public JSONArray getJSONArray(String name) throws JSONException
Returns the value mapped byname
if it exists and is aJSONArray
.- Throws:
JSONException
- if the mapping doesn't exist or is not aJSONArray
.
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optJSONArray
public JSONArray optJSONArray(String name)
Returns the value mapped byname
if it exists and is aJSONArray
. Returns null otherwise.
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getJSONObject
public JSONObject getJSONObject(String name) throws JSONException
Returns the value mapped byname
if it exists and is aJSONObject
.- Throws:
JSONException
- if the mapping doesn't exist or is not aJSONObject
.
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optJSONObject
public JSONObject optJSONObject(String name)
Returns the value mapped byname
if it exists and is aJSONObject
. Returns null otherwise.
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toJSONArray
public JSONArray toJSONArray(JSONArray names) throws JSONException
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
public Iterator 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.
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names
public JSONArray names()
Returns an array containing the string names in this object. This method returns null if this object contains no mappings.
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toString
public String toString()
Encodes this object as a compact JSON string, such as:{"query":"Pizza","locations":[94043,90210]}
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toString
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
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numberToString
public static String numberToString(Number number) throws JSONException
Encodes the number as a JSON string.- Parameters:
number
- a finite value. May not beNaNs
orinfinities
.- Throws:
JSONException
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