processing.data

Class JSONObject

java.lang.Object

processing.data.JSONObject

public class JSONObject
extends java.lang.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. A JSONObject constructor can be used to convert an external form JSON text into an internal form whose values can be retrieved with the get and opt methods, or to convert values into a JSON text using the put and toString methods. 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 coercion for you. The opt methods differ from the get methods in that they do not throw. Instead, they return a specified value, such as null.

The put methods add or replace values in an object. For example,

 myString = new JSONObject().put("JSON", "Hello, World!").toString();
 

produces the string {"JSON": "Hello, World"}.

The texts produced by the toString methods strictly conform to the JSON syntax rules. 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 ; (semicolon) as well as by , (comma).

See Also:

JSONArray, PApplet.loadJSONObject(String), PApplet.loadJSONArray(String), PApplet.saveJSONObject(JSONObject, String), PApplet.saveJSONArray(JSONArray, String)

Field Summary

Fields

Modifier and Type	Field and Description
static java.lang.Object	NULL It is sometimes more convenient and less ambiguous to have a NULL object than to use Java's null value.

Constructor Summary

Constructors

Constructor and Description
JSONObject() Construct an empty JSONObject.
JSONObject(FloatDict dict)
JSONObject(IntDict dict)
JSONObject(java.io.Reader reader)
JSONObject(StringDict dict)

Method Summary

Modifier and Type	Method and Description
java.lang.String	format(int indentFactor) Make a prettyprinted JSON text of this JSONObject.
java.lang.Object	get(java.lang.String key) Get the value object associated with a key.
boolean	getBoolean(java.lang.String key) Get the boolean value associated with a key.
boolean	getBoolean(java.lang.String key, boolean defaultValue) Get an optional boolean associated with a key.
double	getDouble(java.lang.String key) Get the double value associated with a key.
double	getDouble(java.lang.String key, double defaultValue) Get an optional double associated with a key, or the defaultValue if there is no such key or if its value is not a number.
float	getFloat(java.lang.String key)
float	getFloat(java.lang.String key, float defaultValue)
int	getInt(java.lang.String key) Gets the int value associated with a key
int	getInt(java.lang.String key, int defaultValue) Get an optional int value associated with a key, or the default if there is no such key or if the value is not a number.
JSONArray	getJSONArray(java.lang.String key) Get the JSONArray value associated with a key.
JSONObject	getJSONObject(java.lang.String key) Get the JSONObject value associated with a key.
long	getLong(java.lang.String key) Get the long value associated with a key.
long	getLong(java.lang.String key, long defaultValue) Get an optional long value associated with a key, or the default if there is no such key or if the value is not a number.
java.lang.String	getString(java.lang.String key) Gets the String associated with a key
java.lang.String	getString(java.lang.String key, java.lang.String defaultValue) Get an optional string associated with a key.
boolean	hasKey(java.lang.String key) Determine if the JSONObject contains a specific key.
boolean	isNull(java.lang.String key) Determine if the value associated with the key is null or if there is no value.
java.util.Iterator	keyIterator() Get an enumeration of the keys of the JSONObject.
java.util.Set	keys() Get a set of keys of the JSONObject.
static JSONObject	parse(java.lang.String source) Construct a JSONObject from a source JSON text string.
JSONObject	put(java.lang.String key, java.lang.Object value) Put a key/value pair in the JSONObject.
static java.lang.String	quote(java.lang.String string) Produce a string in double quotes with backslash sequences in all the right places.
static java.io.Writer	quote(java.lang.String string, java.io.Writer w)
java.lang.Object	remove(java.lang.String key) Remove a name and its value, if present.
boolean	save(java.io.File file, java.lang.String options)
JSONObject	setBoolean(java.lang.String key, boolean value) Put a key/boolean pair in the JSONObject.
JSONObject	setDouble(java.lang.String key, double value) Put a key/double pair in the JSONObject.
JSONObject	setFloat(java.lang.String key, float value)
JSONObject	setInt(java.lang.String key, int value) Put a key/int pair in the JSONObject.
JSONObject	setJSONArray(java.lang.String key, JSONArray value)
JSONObject	setJSONObject(java.lang.String key, JSONObject value)
JSONObject	setLong(java.lang.String key, long value) Put a key/long pair in the JSONObject.
JSONObject	setString(java.lang.String key, java.lang.String value)
int	size() Get the number of keys stored in the JSONObject.
java.lang.String	toString() Return the JSON data formatted with two spaces for indents.
boolean	write(java.io.PrintWriter output)
boolean	write(java.io.PrintWriter output, java.lang.String options)

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

NULL

public static final java.lang.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(java.io.Reader reader)

JSONObject

public JSONObject(IntDict dict)

JSONObject

public JSONObject(FloatDict dict)

JSONObject

public JSONObject(StringDict dict)

Method Detail

parse

public static JSONObject parse(java.lang.String source)

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

Parameters:

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

Throws:

java.lang.RuntimeException - If there is a syntax error in the source string or a duplicated key.

get

public java.lang.Object get(java.lang.String key)

Get the value object associated with a key.

Parameters:

key - A key string.

Returns:

The object associated with the key.

Throws:

java.lang.RuntimeException - if the key is not found.

getString

public java.lang.String getString(java.lang.String key)

Gets the String associated with a key

Parameters:

key - a key string

Returns:

A string which is the value.

Throws:

java.lang.RuntimeException - if there is no string value for the key.

See Also:

getInt(String), getFloat(String), getBoolean(String)

In brief:

Gets the string value associated with a key

getString

public java.lang.String getString(java.lang.String key,
                                  java.lang.String defaultValue)

Get an optional string associated with a key. It returns the defaultValue if there is no such key.

Parameters:

key - A key string.

defaultValue - The default.

Returns:

A string which is the value.

getInt

public int getInt(java.lang.String key)

Gets the int value associated with a key

Parameters:

key - A key string.

Returns:

The integer value.

Throws:

java.lang.RuntimeException - if the key is not found or if the value cannot be converted to an integer.

See Also:

getFloat(String), getString(String), getBoolean(String)

In brief:

Gets the int value associated with a key

getInt

public int getInt(java.lang.String key,
                  int defaultValue)

Get an optional int value associated with a key, or the default if there is no such key or if the value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

Parameters:

key - A key string.

defaultValue - The default.

Returns:

An object which is the value.

getLong

public long getLong(java.lang.String key)

Get the long value associated with a key.

Parameters:

key - A key string.

Returns:

The long value.

Throws:

java.lang.RuntimeException - if the key is not found or if the value cannot be converted to a long.

getLong

public long getLong(java.lang.String key,
                    long defaultValue)

Get an optional long value associated with a key, or the default if there is no such key or if the value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

Parameters:

key - A key string.

defaultValue - The default.

Returns:

An object which is the value.

getFloat

public float getFloat(java.lang.String key)

Parameters:

key - a key string

See Also:

getInt(String), getString(String), getBoolean(String)

In brief:

Gets the float value associated with a key

getFloat

public float getFloat(java.lang.String key,
                      float defaultValue)

getDouble

public double getDouble(java.lang.String key)

Get the double value associated with a key.

Parameters:

key - A key string.

Returns:

The numeric value.

Throws:

java.lang.RuntimeException - if the key is not found or if the value is not a Number object and cannot be converted to a number.

getDouble

public double getDouble(java.lang.String key,
                        double defaultValue)

Get an optional double associated with a key, or the defaultValue if there is no such key or if its value is not a number. If the value is a string, an attempt will be made to evaluate it as a number.

Parameters:

key - A key string.

defaultValue - The default.

Returns:

An object which is the value.

getBoolean

public boolean getBoolean(java.lang.String key)

Get the boolean value associated with a key.

Parameters:

key - a key string

Returns:

The truth.

Throws:

java.lang.RuntimeException - if the value is not a Boolean or the String "true" or "false".

See Also:

getInt(String), getFloat(String), getString(String)

In brief:

Gets the boolean value associated with a key

getBoolean

public boolean getBoolean(java.lang.String key,
                          boolean defaultValue)

Get an optional boolean associated with a key. It returns the defaultValue if there is no such key, or if it is not a Boolean or the String "true" or "false" (case insensitive).

Parameters:

key - A key string.

defaultValue - The default.

Returns:

The truth.

getJSONArray

public JSONArray getJSONArray(java.lang.String key)

Get the JSONArray value associated with a key.

Parameters:

key - a key string

Returns:

A JSONArray which is the value, or null if not present

Throws:

java.lang.RuntimeException - if the value is not a JSONArray.

See Also:

getJSONObject(String), setJSONObject(String, JSONObject), setJSONArray(String, JSONArray)

In brief:

Gets the JSONArray value associated with a key

getJSONObject

public JSONObject getJSONObject(java.lang.String key)

Get the JSONObject value associated with a key.

Parameters:

key - a key string

Returns:

A JSONObject which is the value or null if not available.

Throws:

java.lang.RuntimeException - if the value is not a JSONObject.

See Also:

getJSONArray(String), setJSONObject(String, JSONObject), setJSONArray(String, JSONArray)

In brief:

Gets the JSONObject value associated with a key

hasKey

public boolean hasKey(java.lang.String key)

Determine if the JSONObject contains a specific key.

Parameters:

key - A key string.

Returns:

true if the key exists in the JSONObject.

isNull

public boolean isNull(java.lang.String key)

Determine if the value associated with the key is null or if there is no value.

Parameters:

key - A key string.

Returns:

true if there is no value associated with the key or if the value is the JSONObject.NULL object.

keyIterator

public java.util.Iterator keyIterator()

Get an enumeration of the keys of the JSONObject.

Returns:

An iterator of the keys.

keys

public java.util.Set keys()

Get a set of keys of the JSONObject.

Returns:

A keySet.

size

public int size()

Get the number of keys stored in the JSONObject.

Returns:

The number of keys in the JSONObject.

setString

public JSONObject setString(java.lang.String key,
                            java.lang.String value)

Parameters:

key - a key string

value - the value to assign

See Also:

setInt(String, int), setFloat(String, float), setBoolean(String, boolean)

In brief:

Put a key/String pair in the JSONObject

setInt

public JSONObject setInt(java.lang.String key,
                         int value)

Put a key/int pair in the JSONObject.

Parameters:

key - a key string

value - the value to assign

Returns:

this.

Throws:

java.lang.RuntimeException - If the key is null.

See Also:

setFloat(String, float), setString(String, String), setBoolean(String, boolean)

In brief:

Put a key/int pair in the JSONObject

setLong

public JSONObject setLong(java.lang.String key,
                          long value)

Put a key/long pair in the JSONObject.

Parameters:

key - A key string.

value - A long which is the value.

Returns:

this.

Throws:

java.lang.RuntimeException - If the key is null.

setFloat

public JSONObject setFloat(java.lang.String key,
                           float value)

Parameters:

key - a key string

value - the value to assign

Throws:

java.lang.RuntimeException - If the key is null or if the number is NaN or infinite.

See Also:

setInt(String, int), setString(String, String), setBoolean(String, boolean)

In brief:

Put a key/float pair in the JSONObject

setDouble

public JSONObject setDouble(java.lang.String key,
                            double value)

Put a key/double pair in the JSONObject.

Parameters:

key - A key string.

value - A double which is the value.

Returns:

this.

Throws:

java.lang.RuntimeException - If the key is null or if the number is NaN or infinite.

setBoolean

public JSONObject setBoolean(java.lang.String key,
                             boolean value)

Put a key/boolean pair in the JSONObject.

Parameters:

key - a key string

value - the value to assign

Returns:

this.

Throws:

java.lang.RuntimeException - If the key is null.

See Also:

setInt(String, int), setFloat(String, float), setString(String, String)

In brief:

Put a key/boolean pair in the JSONObject

setJSONObject

public JSONObject setJSONObject(java.lang.String key,
                                JSONObject value)

Parameters:

key - a key string

value - value to assign

See Also:

setJSONArray(String, JSONArray), getJSONObject(String), getJSONArray(String)

In brief:

Sets the JSONObject value associated with a key

setJSONArray

public JSONObject setJSONArray(java.lang.String key,
                               JSONArray value)

Parameters:

key - a key string

value - value to assign

See Also:

setJSONObject(String, JSONObject), getJSONObject(String), getJSONArray(String)

In brief:

Sets the JSONArray value associated with a key

put

public JSONObject put(java.lang.String key,
                      java.lang.Object value)

Put a key/value pair in the JSONObject. If the value is null, then the key will be removed from the JSONObject if it is present.

Parameters:

key - A key string.

value - An object which is the value. It should be of one of these types: Boolean, Double, Integer, JSONArray, JSONObject, Long, String, or the JSONObject.NULL object.

Returns:

this.

Throws:

java.lang.RuntimeException - If the value is non-finite number or if the key is null.

quote

public static java.lang.String quote(java.lang.String string)

Produce a string in double quotes with backslash sequences in all the right places. A backslash will be inserted within

Parameters:

string - A String

Returns:

A String correctly formatted for insertion in a JSON text.

quote

public static java.io.Writer quote(java.lang.String string,
                                   java.io.Writer w)
                            throws java.io.IOException

Throws:

java.io.IOException

remove

public java.lang.Object remove(java.lang.String key)

Remove a name and its value, if present.

Parameters:

key - The name to be removed.

Returns:

The value that was associated with the name, or null if there was no value.

save

public boolean save(java.io.File file,
                    java.lang.String options)

write

public boolean write(java.io.PrintWriter output)

write

public boolean write(java.io.PrintWriter output,
                     java.lang.String options)

toString

public java.lang.String toString()

Return the JSON data formatted with two spaces for indents. Chosen to do this since it's the most common case (e.g. with println()). Same as format(2). Use the format() function for more options.

Overrides:

toString in class java.lang.Object

format

public java.lang.String format(int indentFactor)

Make a prettyprinted JSON text of this JSONObject.

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, portable, transmittable representation of the object, beginning with { (left brace) and ending with } (right brace).

Throws:

java.lang.RuntimeException - If the object contains an invalid number.