org.apache.tapestry.json
Class JSONObject

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

public class JSONObject
extends Object

A JSONObject is an unordered collection of name/value pairs. Its external form is a string wrapped in curly braces with colons between the names and values, and commas between the values and names. The internal form is an object having get() and opt() methods for accessing the values by name, and put() methods for adding or replacing values by name. The values can be any of these types: Boolean, JSONArray, JSONObject, Number, String, or the JSONObject.NULL object.

The constructor can convert an 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 type 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 brace.
• 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.
• Keys can be followed by = or => as well as by :
• 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

Field Summary

static Object

NULL It is sometimes more convenient and less ambiguous to have a NULL object than to use Java's null value.

Constructor Summary

JSONObject()
Construct an empty JSONObject.

JSONObject(JSONObject jo, String[] sa)
Construct a JSONObject from a subset of another JSONObject.

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

JSONObject(Map map)
Construct a JSONObject from a Map.

JSONObject(String string)
Construct a JSONObject from a string.

Method Summary

JSONObject	accumulate(String key, Object value)
Object	get(String key)
boolean	getBoolean(String key)
double	getDouble(String key)
int	getInt(String key)
JSONArray	getJSONArray(String key)
JSONObject	getJSONObject(String key)
String	getString(String key)
boolean	has(String key)
boolean	isNull(String key)
Iterator	keys()
int	length()
JSONArray	names()
static String	numberToString(Number n) Produce a string from a number.
Object	opt(String key)
boolean	optBoolean(String key)
boolean	optBoolean(String key, boolean defaultValue)
double	optDouble(String key)
double	optDouble(String key, double defaultValue)
int	optInt(String key)
int	optInt(String key, int defaultValue)
JSONArray	optJSONArray(String key)
JSONObject	optJSONObject(String key)
String	optString(String key)
String	optString(String key, String defaultValue)
JSONObject	put(Object key, boolean value)
JSONObject	put(Object key, double value)
JSONObject	put(Object key, int value)
JSONObject	put(Object key, long value)
JSONObject	put(Object key, Object value)
JSONObject	putOpt(String key, Object value)
static String	quote(char value)
static String	quote(String string) Produce a string in double quotes with backslash sequences in all the right places.
Object	remove(String key)
JSONArray	toJSONArray(JSONArray names)
String	toString()
String	toString(int indentFactor)

Methods inherited from class java.lang.Object

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

Field Detail

NULL

public static final Object NULL

It is sometimes more convenient and less ambiguous to have a NULL object than to use Java's null value. JSONObject.NULL.equals(null) returns true. JSONObject.NULL.toString() returns "null".

Constructor Detail

JSONObject

public JSONObject()

Construct an empty JSONObject.

JSONObject

public JSONObject(JSONObject jo,
                  String[] sa)

Construct a JSONObject from a subset of another JSONObject. An array of strings is used to identify the keys that should be copied. Missing keys are ignored.

Parameters:

jo - A JSONObject.

sa - An array of strings.

JSONObject

public JSONObject(JSONTokener x)
           throws ParseException

Construct a JSONObject from a JSONTokener.

Parameters:

x - A JSONTokener object containing the source string.

Throws:

ParseException - if there is a syntax error in the source string.

JSONObject

public JSONObject(Map map)

Construct a JSONObject from a Map.

Parameters:

map - A map object that can be used to initialize the contents of the JSONObject.

JSONObject

public JSONObject(String string)
           throws ParseException

Construct a JSONObject from a string. This is the most commonly used JSONObject constructor.

Parameters:

string - A string beginning with { (left brace) and ending with } (right brace).

Throws:

ParseException - The string must be properly formatted.

Method Detail

accumulate

public JSONObject accumulate(String key,
                             Object value)

get

public Object get(String key)

getBoolean

public boolean getBoolean(String key)

getDouble

public double getDouble(String key)

getInt

public int getInt(String key)

getJSONArray

public JSONArray getJSONArray(String key)

getJSONObject

public JSONObject getJSONObject(String key)

getString

public String getString(String key)

has

public boolean has(String key)

isNull

public boolean isNull(String key)

keys

public Iterator keys()

length

public int length()

names

public JSONArray names()

numberToString

public static String numberToString(Number n)

Produce a string from a number.

Parameters:

n - A Number

Returns:

A String.

Throws:

ArithmeticException - JSON can only serialize finite numbers.

opt

public Object opt(String key)

optBoolean

public boolean optBoolean(String key)

optBoolean

public boolean optBoolean(String key,
                          boolean defaultValue)

optDouble

public double optDouble(String key)

optDouble

public double optDouble(String key,
                        double defaultValue)

optInt

public int optInt(String key)

optInt

public int optInt(String key,
                  int defaultValue)

optJSONArray

public JSONArray optJSONArray(String key)

optJSONObject

public JSONObject optJSONObject(String key)

optString

public String optString(String key)

optString

public String optString(String key,
                        String defaultValue)

put

public JSONObject put(Object key,
                      boolean value)

put

public JSONObject put(Object key,
                      double value)

put

public JSONObject put(Object key,
                      long value)

put

public JSONObject put(Object key,
                      int value)

put

public JSONObject put(Object key,
                      Object value)

putOpt

public JSONObject putOpt(String key,
                         Object value)

quote

public static String quote(char value)

Parameters:

value -

Returns:

The character quoted.

See Also:

.

quote

public static String quote(String string)

Produce a string in double quotes with backslash sequences in all the right places.

Parameters:

string - A String

Returns:

A String correctly formatted for insertion in a JSON message.

remove

public Object remove(String key)

toJSONArray

public JSONArray toJSONArray(JSONArray names)

toString

public String toString()

Overrides:

toString in class Object

toString

public String toString(int indentFactor)