org.apache.tapestry.json
Class JSONArray

java.lang.Object
  org.apache.tapestry.json.JSONArray

public final class JSONArray
extends Object

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.

Version:

2

Author:

JSON.org

Constructor Summary

JSONArray()
Construct an empty JSONArray.

JSONArray(String text)

Method Summary

boolean	equals(Object obj)
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.
long	getLong(int index) Get the long value associated with an index.
String	getString(int index) Get the string associated with an index.
boolean	isNull(int index) Determine if the value is null.
String	join(String separator) Make a string from the contents of this JSONArray.
int	length() Get the number of elements in the JSONArray, included nulls.
JSONArray	put(int index, Object value) Put or replace an object value in the JSONArray.
JSONArray	put(Object value) Append an object value.
String	toString() Make a JSON text of this JSONArray.

Methods inherited from class java.lang.Object

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

Constructor Detail

JSONArray

public JSONArray()

Construct an empty JSONArray.

JSONArray

public JSONArray(String text)

Method Detail

get

public Object get(int index)

Get the object value associated with an index.

Parameters:

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

Returns:

An object value.

Throws:

RuntimeException - If there is no value for the index.

getBoolean

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.

Returns:

The truth.

Throws:

RuntimeException - If there is no value for the index or if the value is not convertable to boolean.

getDouble

public double getDouble(int index)

Get the double value associated with an index.

Parameters:

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

Returns:

The value.

Throws:

IllegalArgumentException - If the key is not found or if the value cannot be converted to a number.

getInt

public int getInt(int index)

Get the int value associated with an index.

Parameters:

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

Returns:

The value.

Throws:

IllegalArgumentException - 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.

getJSONArray

public JSONArray getJSONArray(int index)

Get the JSONArray associated with an index.

Parameters:

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

Returns:

A JSONArray value.

Throws:

RuntimeException - If there is no value for the index. or if the value is not a JSONArray

getJSONObject

public JSONObject getJSONObject(int index)

Get the JSONObject associated with an index.

Parameters:

index - subscript

Returns:

A JSONObject value.

Throws:

RuntimeException - If there is no value for the index or if the value is not a JSONObject

getLong

public long getLong(int index)

Get the long value associated with an index.

Parameters:

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

Returns:

The value.

Throws:

IllegalArgumentException - If the key is not found or if the value cannot be converted to a number.

getString

public String getString(int index)

Get the string associated with an index.

Parameters:

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

Returns:

A string value.

Throws:

RuntimeException - If there is no value for the index.

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 String join(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.

Throws:

RuntimeException - If the array contains an invalid number.

length

public int length()

Get the number of elements in the JSONArray, included nulls.

Returns:

The length (or size).

put

public JSONArray put(Object value)

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, JSONObject, Long, or String, or the JSONObject.NULL object.

Returns:

put

public JSONArray put(int index,
                     Object value)

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

Returns:

Throws:

RuntimeException - If the index is negative or if the the value is an invalid number.

toString

public String toString()

Make a 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.

Overrides:

toString in class Object

Returns:

a printable, displayable, transmittable representation of the array.

equals

public boolean equals(Object obj)

Overrides:

equals in class Object