org.json
Class JSONArray

java.lang.Object
  org.json.JSONArray

public class JSONArray
extends java.lang.Object

A JSONArray is an ordered sequence of values. Its external form is a string wrapped in square brackets with commas between 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 external form string into an internal form Java object. The toString() method creates an external form string.

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 typing checking and type coersion for you.

The texts produced by the toString() methods are very strict. 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 followed by ; as well as by ,
• Numbers may have the 0- (octal) or 0x- (hex) prefix.
• Line comments can begin with #

Version:

1

Author:

JSON.org

Constructor Summary

JSONArray()
Construct an empty JSONArray.

JSONArray(java.util.Collection collection)
Construct a JSONArray from a Collection.

JSONArray(JSONTokener x)
Construct a JSONArray from a JSONTokener.

JSONArray(java.lang.String string)
Construct a JSONArray from a source string.

Method Summary

java.lang.Object	get(int index) Get the object value associated with an index.
boolean	getBoolean(int index) Get the boolean value associated with an index.
double	getDouble(int index) Get the double value associated with an index.
int	getInt(int index) Get the int value associated with an index.
JSONArray	getJSONArray(int index) Get the JSONArray associated with an index.
JSONObject	getJSONObject(int index) Get the JSONObject associated with an index.
java.lang.String	getString(int index) Get the string associated with an index.
boolean	isNull(int index) Determine if the value is null.
java.lang.String	join(java.lang.String separator) Make a string from the contents of this JSONArray.
int	length() Get the length of the JSONArray.
java.lang.Object	opt(int index) Get the optional object value associated with an index.
boolean	optBoolean(int index) Get the optional boolean value associated with an index.
boolean	optBoolean(int index, boolean defaultValue) Get the optional boolean value associated with an index.
double	optDouble(int index) Get the optional double value associated with an index.
double	optDouble(int index, double defaultValue) Get the optional double value associated with an index.
int	optInt(int index) Get the optional int value associated with an index.
int	optInt(int index, int defaultValue) Get the optional int value associated with an index.
JSONArray	optJSONArray(int index) Get the optional JSONArray associated with an index.
JSONObject	optJSONObject(int index) Get the optional JSONObject associated with an index.
java.lang.String	optString(int index) Get the optional string value associated with an index.
java.lang.String	optString(int index, java.lang.String defaultValue) Get the optional string associated with an index.
JSONArray	put(boolean value) Append a boolean value.
JSONArray	put(double value) Append a double value.
JSONArray	put(int value) Append an int value.
JSONArray	put(int index, boolean value) Put or replace a boolean value in the JSONArray.
JSONArray	put(int index, double value) Put or replace a double value.
JSONArray	put(int index, int value) Put or replace an int value.
JSONArray	put(int index, java.lang.Object value) Put or replace an object value in the JSONArray.
JSONArray	put(java.lang.Object value) Append an object value.
JSONObject	toJSONObject(JSONArray names) Produce a JSONObject by combining a JSONArray of names with the values of this JSONArray.
java.lang.String	toString() Make an JSON external form string of this JSONArray.
java.lang.String	toString(int indentFactor) Make a prettyprinted JSON string of this JSONArray.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

JSONArray

public JSONArray()

Construct an empty JSONArray.

JSONArray

public JSONArray(JSONTokener x)
          throws java.text.ParseException

Construct a JSONArray from a JSONTokener.

Parameters:

x - A JSONTokener

Throws:

java.text.ParseException - A JSONArray must start with '['

java.text.ParseException - Expected a ',' or ']'

JSONArray

public JSONArray(java.lang.String string)
          throws java.text.ParseException

Construct a JSONArray from a source string.

Parameters:

string - A string that begins with [ (left bracket) and ends with ] (right bracket).

Throws:

java.text.ParseException - The string must conform to JSON syntax.

JSONArray

public JSONArray(java.util.Collection collection)

Construct a JSONArray from a Collection.

Parameters:

collection - A Collection.

Method Detail

get

public java.lang.Object get(int index)
                     throws java.util.NoSuchElementException

Get the object value associated with an index.

Parameters:

index - The index must be between 0 and length() - 1.

Returns:

An object value.

Throws:

java.util.NoSuchElementException

getBoolean

public boolean getBoolean(int index)
                   throws java.lang.ClassCastException,
                          java.util.NoSuchElementException

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.

Returns:

The truth.

Throws:

java.util.NoSuchElementException - if the index is not found

java.lang.ClassCastException

getDouble

public double getDouble(int index)
                 throws java.util.NoSuchElementException,
                        java.lang.NumberFormatException

Get the double value associated with an index.

Parameters:

index - The index must be between 0 and length() - 1.

Returns:

The value.

Throws:

java.util.NoSuchElementException - if the key is not found

java.lang.NumberFormatException - if the value cannot be converted to a number.

getInt

public int getInt(int index)
           throws java.util.NoSuchElementException,
                  java.lang.NumberFormatException

Get the int value associated with an index.

Parameters:

index - The index must be between 0 and length() - 1.

Returns:

The value.

Throws:

java.util.NoSuchElementException - if the key is not found

java.lang.NumberFormatException - if the value cannot be converted to a number.

getJSONArray

public JSONArray getJSONArray(int index)
                       throws java.util.NoSuchElementException

Get the JSONArray associated with an index.

Parameters:

index - The index must be between 0 and length() - 1.

Returns:

A JSONArray value.

Throws:

java.util.NoSuchElementException - if the index is not found or if the value is not a JSONArray

getJSONObject

public JSONObject getJSONObject(int index)
                         throws java.util.NoSuchElementException

Get the JSONObject associated with an index.

Parameters:

index - subscript

Returns:

A JSONObject value.

Throws:

java.util.NoSuchElementException - if the index is not found or if the value is not a JSONObject

getString

public java.lang.String getString(int index)
                           throws java.util.NoSuchElementException

Get the string associated with an index.

Parameters:

index - The index must be between 0 and length() - 1.

Returns:

A string value.

Throws:

java.util.NoSuchElementException

isNull

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.

join

public java.lang.String join(java.lang.String separator)

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.

Returns:

a string.

length

public int length()

Get the length of the JSONArray.

Returns:

The length (or size).

opt

public java.lang.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.

optBoolean

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.

Returns:

The truth.

optBoolean

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.

Returns:

The truth.

optDouble

public double optDouble(int index)

Get the optional double value associated with an index. NaN is returned if the index is not found, 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.

Returns:

The value.

optDouble

public double optDouble(int index,
                        double defaultValue)

Get the optional double value associated with an index. The defaultValue is returned if the index is not found, or if the value is not a number and cannot be converted to a number.

Parameters:

index - subscript

defaultValue - The default value.

Returns:

The value.

optInt

public int optInt(int index)

Get the optional int value associated with an index. Zero is returned if the index is not found, 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.

Returns:

The value.

optInt

public int optInt(int index,
                  int defaultValue)

Get the optional int value associated with an index. The defaultValue is returned if the index is not found, 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.

Returns:

The value.

optJSONArray

public JSONArray optJSONArray(int index)

Get the optional JSONArray associated with an index.

Parameters:

index - subscript

Returns:

A JSONArray value, or null if the index has no value, or if the value is not a JSONArray.

optJSONObject

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.

Returns:

A JSONObject value.

optString

public java.lang.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.

Returns:

A String value.

optString

public java.lang.String optString(int index,
                                  java.lang.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.

Returns:

A String value.

put

public JSONArray put(boolean value)

Append a boolean value.

Parameters:

value - A boolean value.

Returns:

this.

put

public JSONArray put(double value)

Append a double value.

Parameters:

value - A double value.

Returns:

this.

put

public JSONArray put(int value)

Append an int value.

Parameters:

value - An int value.

Returns:

this.

put

public JSONArray put(java.lang.Object value)

Append an object value.

Parameters:

value - An object value. The value should be a Boolean, Double, Integer, JSONArray, JSObject, or String, or the JSONObject.NULL object.

Returns:

this.

put

public JSONArray put(int index,
                     boolean value)

Put or replace a boolean value in the JSONArray.

Parameters:

index - subscript The subscript. If the index is greater than the length of the JSONArray, then null elements will be added as necessary to pad it out.

value - A boolean value.

Returns:

this.

Throws:

java.util.NoSuchElementException - The index must not be negative.

put

public JSONArray put(int index,
                     double value)

Put or replace a double value.

Parameters:

index - subscript The subscript. If the index is greater than the length of the JSONArray, then null elements will be added as necessary to pad it out.

value - A double value. return this.

Throws:

java.util.NoSuchElementException - The index must not be negative.

put

public JSONArray put(int index,
                     int value)

Put or replace an int value.

Parameters:

index - subscript The subscript. If the index is greater than the length of the JSONArray, then null elements will be added as necessary to pad it out.

value - An int value.

Returns:

this.

Throws:

java.util.NoSuchElementException - The index must not be negative.

put

public JSONArray put(int index,
                     java.lang.Object value)
              throws java.util.NoSuchElementException,
                     java.lang.NullPointerException

Put or replace an object value in the JSONArray.

Parameters:

index - The subscript. If the index is greater than the length of the JSONArray, then null elements will be added as necessary to pad it out.

value - An object value. return this.

Throws:

java.util.NoSuchElementException - The index must not be negative.

java.lang.NullPointerException

toJSONObject

public JSONObject toJSONObject(JSONArray names)

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.

toString

public java.lang.String toString()

Make an JSON external form string of this JSONArray. For compactness, no unnecessary whitespace is added. Warning: This method assumes that the data structure is acyclical.

Overrides:

toString in class java.lang.Object

Returns:

a printable, displayable, transmittable representation of the array.

toString

public java.lang.String toString(int indentFactor)

Make a prettyprinted JSON string of this JSONArray. Warning: This method assumes that the data structure is non-cyclical.

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).