org.json.JSONArray
A JSONArray is an ordered sequence of values. Its external text form is a
string wrapped in square brackets with commas separating the values. The
internal form is an object having get
and opt
methods for accessing the values by index, and put
methods for
adding or replacing values. The values can be any of these types:
Boolean
, JSONArray
, JSONObject
,
Number
, String
, or the
JSONObject.NULL object
.
The constructor can convert a JSON text into a Java object. The
toString
method converts to JSON text.
A get
method returns a value if one can be found, and throws an
exception if one cannot be found. An opt
method returns a
default value instead of throwing an exception, and so is useful for
obtaining optional values.
The generic get()
and opt()
methods return an
object which you can cast or query for type. There are also typed
get
and opt
methods that do type checking and type
coersion for you.
The texts produced by the toString
methods strictly conform to
JSON syntax rules. The constructors are more forgiving in the texts they will
accept:
- An extra
,
(comma) may appear just
before the closing bracket.
- The
null
value will be inserted when there
is ,
(comma) elision.
- Strings may be quoted with
'
(single
quote).
- Strings do not need to be quoted at all if they do not begin with a quote
or single quote, and if they do not contain leading or trailing spaces,
and if they do not contain any of these characters:
{ } [ ] / \ : , = ; #
and if they do not look like numbers
and if they are not the reserved words true
,
false
, or null
.
- Values can be separated by
;
(semicolon) as
well as by ,
(comma).
- Numbers may have the
0-
(octal) or
0x-
(hex) prefix.
- Comments written in the slashshlash, slashstar, and hash conventions
will be ignored.
Summary
Public Constructors
Public Methods
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boolean |
equals(Object object) |
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Object |
get(int index) |
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boolean |
getBoolean(int index) |
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double |
getDouble(int index) |
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int |
getInt(int index) |
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JSONArray |
getJSONArray(int index) |
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JSONObject |
getJSONObject(int index) |
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long |
getLong(int index) |
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String |
getString(int index) |
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boolean |
isNull(int index) |
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String |
join(String separator) |
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int |
length() |
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Object |
opt(int index) |
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boolean |
optBoolean(int index, boolean defaultValue) |
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boolean |
optBoolean(int index) |
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double |
optDouble(int index, double defaultValue) |
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double |
optDouble(int index) |
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int |
optInt(int index, int defaultValue) |
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int |
optInt(int index) |
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JSONArray |
optJSONArray(int index) |
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JSONObject |
optJSONObject(int index) |
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long |
optLong(int index, long defaultValue) |
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long |
optLong(int index) |
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String |
optString(int index) |
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String |
optString(int index, String defaultValue) |
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JSONArray |
put(int index, boolean value) |
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JSONArray |
put(int index, long value) |
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JSONArray |
put(boolean value) |
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JSONArray |
put(long value) |
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JSONArray |
put(int value) |
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JSONArray |
put(int index, Object value) |
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JSONArray |
put(Object value) |
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JSONArray |
put(int index, double value) |
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JSONArray |
put(double value) |
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JSONArray |
put(int index, int value) |
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JSONObject |
toJSONObject(JSONArray names) |
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String |
toString() |
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String |
toString(int indentFactor) |
clone,
equals,
finalize,
getClass,
hashCode,
notify,
notifyAll,
toString,
wait,
wait,
wait
Details
Public Constructors
public
JSONArray()
Construct an empty JSONArray.
Construct a JSONArray from a JSONTokener.
public
JSONArray(String string)
Construct a JSONArray from a source sJSON text.
Parameters
string
| A string that begins with
[ (left bracket)
and ends with ] (right bracket). |
public
JSONArray(Collection collection)
Construct a JSONArray from a Collection.
Public Methods
public
boolean
equals(Object object)
Compares the argument to the receiver, and returns true if they represent
the
same object using a class specific comparison. The
implementation in Object returns true only if the argument is the exact
same object as the receiver (==).
Parameters
object
| Object the object to compare with this object. |
Returns
- boolean
true
if the object is the same as this
object false
if it is different from this object.
public
Object
get(int index)
Get the object value associated with an index.
Parameters
index
| The index must be between 0 and length() - 1. |
public
boolean
getBoolean(int index)
Get the boolean value associated with an index.
The string values "true" and "false" are converted to boolean.
Parameters
index
| The index must be between 0 and length() - 1. |
Throws
JSONException
| If there is no value for the index or if the
value is not convertable to boolean.
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public
double
getDouble(int index)
Get the double value associated with an index.
Parameters
index
| The index must be between 0 and length() - 1. |
Throws
JSONException
| If the key is not found or if the value cannot
be converted to a number.
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public
int
getInt(int index)
Get the int value associated with an index.
Parameters
index
| The index must be between 0 and length() - 1. |
Throws
JSONException
| If the key is not found or if the value cannot
be converted to a number.
if the value cannot be converted to a number.
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public
JSONArray
getJSONArray(int index)
Get the JSONArray associated with an index.
Parameters
index
| The index must be between 0 and length() - 1. |
Throws
JSONException
| If there is no value for the index. or if the
value is not a JSONArray
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public
JSONObject
getJSONObject(int index)
Get the JSONObject associated with an index.
Throws
JSONException
| If there is no value for the index or if the
value is not a JSONObject
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public
long
getLong(int index)
Get the long value associated with an index.
Parameters
index
| The index must be between 0 and length() - 1. |
Throws
JSONException
| If the key is not found or if the value cannot
be converted to a number.
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public
String
getString(int index)
Get the string associated with an index.
Parameters
index
| The index must be between 0 and length() - 1. |
public
boolean
isNull(int index)
Determine if the value is null.
Parameters
index
| The index must be between 0 and length() - 1. |
Returns
- true if the value at the index is null, or if there is no value.
Make a string from the contents of this JSONArray. The
separator
string is inserted between each element.
Warning: This method assumes that the data structure is acyclical.
Parameters
separator
| A string that will be inserted between the elements. |
public
int
length()
Get the number of elements in the JSONArray, included nulls.
public
Object
opt(int index)
Get the optional object value associated with an index.
Parameters
index
| The index must be between 0 and length() - 1. |
Returns
- An object value, or null if there is no
object at that index.
public
boolean
optBoolean(int index, boolean defaultValue)
Get the optional boolean value associated with an index.
It returns the defaultValue if there is no value at that index or if
it is not a Boolean or the String "true" or "false" (case insensitive).
Parameters
index
| The index must be between 0 and length() - 1. |
defaultValue
| A boolean default. |
public
boolean
optBoolean(int index)
Get the optional boolean value associated with an index.
It returns false if there is no value at that index,
or if the value is not Boolean.TRUE or the String "true".
Parameters
index
| The index must be between 0 and length() - 1. |
public
double
optDouble(int index, double defaultValue)
Get the optional double value associated with an index.
The defaultValue is returned if there is no value for the index,
or if the value is not a number and cannot be converted to a number.
Parameters
index
| subscript |
defaultValue
| The default value. |
public
double
optDouble(int index)
Get the optional double value associated with an index.
NaN is returned if there is no value for the index,
or if the value is not a number and cannot be converted to a number.
Parameters
index
| The index must be between 0 and length() - 1. |
public
int
optInt(int index, int defaultValue)
Get the optional int value associated with an index.
The defaultValue is returned if there is no value for the index,
or if the value is not a number and cannot be converted to a number.
Parameters
index
| The index must be between 0 and length() - 1. |
defaultValue
| The default value. |
public
int
optInt(int index)
Get the optional int value associated with an index.
Zero is returned if there is no value for the index,
or if the value is not a number and cannot be converted to a number.
Parameters
index
| The index must be between 0 and length() - 1. |
public
JSONArray
optJSONArray(int index)
Get the optional JSONArray associated with an index.
Returns
- A JSONArray value, or null if the index has no value,
or if the value is not a JSONArray.
public
JSONObject
optJSONObject(int index)
Get the optional JSONObject associated with an index.
Null is returned if the key is not found, or null if the index has
no value, or if the value is not a JSONObject.
Parameters
index
| The index must be between 0 and length() - 1. |
public
long
optLong(int index, long defaultValue)
Get the optional long value associated with an index.
The defaultValue is returned if there is no value for the index,
or if the value is not a number and cannot be converted to a number.
Parameters
index
| The index must be between 0 and length() - 1. |
defaultValue
| The default value. |
public
long
optLong(int index)
Get the optional long value associated with an index.
Zero is returned if there is no value for the index,
or if the value is not a number and cannot be converted to a number.
Parameters
index
| The index must be between 0 and length() - 1. |
public
String
optString(int index)
Get the optional string value associated with an index. It returns an
empty string if there is no value at that index. If the value
is not a string and is not null, then it is coverted to a string.
Parameters
index
| The index must be between 0 and length() - 1. |
public
String
optString(int index, String defaultValue)
Get the optional string associated with an index.
The defaultValue is returned if the key is not found.
Parameters
index
| The index must be between 0 and length() - 1. |
defaultValue
| The default value. |
public
JSONArray
put(int index, boolean value)
Put or replace a boolean value in the JSONArray. If the index is greater
than the length of the JSONArray, then null elements will be added as
necessary to pad it out.
Parameters
index
| The subscript. |
value
| A boolean value. |
public
JSONArray
put(int index, long value)
Put or replace a long value. If the index is greater than the length of
the JSONArray, then null elements will be added as necessary to pad
it out.
Parameters
index
| The subscript. |
value
| A long value. |
public
JSONArray
put(boolean value)
Append a boolean value. This increases the array's length by one.
public
JSONArray
put(long value)
Append an long value. This increases the array's length by one.
public
JSONArray
put(int value)
Append an int value. This increases the array's length by one.
Put or replace an object value in the JSONArray. If the index is greater
than the length of the JSONArray, then null elements will be added as
necessary to pad it out.
Parameters
index
| The subscript. |
value
| The value to put into the array. |
Throws
JSONException
| If the index is negative or if the the value is
an invalid number.
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Append an object value. This increases the array's length by one.
Parameters
value
| An object value. The value should be a
Boolean, Double, Integer, JSONArray, JSObject, Long, or String, or the
JSONObject.NULL object. |
public
JSONArray
put(int index, double value)
Put or replace a double value. If the index is greater than the length of
the JSONArray, then null elements will be added as necessary to pad
it out.
Parameters
index
| The subscript. |
value
| A double value. |
Throws
JSONException
| If the index is negative or if the value is
not finite.
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public
JSONArray
put(double value)
Append a double value. This increases the array's length by one.
public
JSONArray
put(int index, int value)
Put or replace an int value. If the index is greater than the length of
the JSONArray, then null elements will be added as necessary to pad
it out.
Parameters
index
| The subscript. |
value
| An int value. |
Produce a JSONObject by combining a JSONArray of names with the values
of this JSONArray.
Parameters
names
| A JSONArray containing a list of key strings. These will be
paired with the values. |
Returns
- A JSONObject, or null if there are no names or if this JSONArray
has no values.
public
String
toString()
Make an JSON text of this JSONArray. For compactness, no
unnecessary whitespace is added. If it is not possible to produce a
syntactically correct JSON text then null will be returned instead. This
could occur if the array contains an invalid number.
Warning: This method assumes that the data structure is acyclical.
Returns
- a printable, displayable, transmittable
representation of the array.
public
String
toString(int indentFactor)
Make a prettyprinted JSON text of this JSONArray.
Warning: This method assumes that the data structure is acyclical.
Parameters
indentFactor
| The number of spaces to add to each level of
indentation. |
Returns
- a printable, displayable, transmittable
representation of the object, beginning
with
[
(left bracket) and ending
with ]
(right bracket).