com.purplehillsbooks.json

Class JSONObject

java.lang.Object

com.purplehillsbooks.json.JSONObject

public class JSONObject
extends java.lang.Object

A JSONObject is an collection of name/value pairs.

This com.purplehillsbooks.json version of the classes enforces alphabetical order on the object members when being serialized. This is done to put the output into a cononical, reproducible form. So that identical JSON objects will produce identical output, and so that if you compare two JSON files, the difference will be more meaningful. Otherwise, the order of the members does not matter.

This com.purplehillsbooks.json version also provides human readible, indented output when you use the write(stream, indent, offset) method.

The JSONObject serialized 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 casting for you. The opt methods differ from the get methods in that they do not throw. Instead, they return a specified default value, such as null or zero.

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

 JSONObject myObj = new JSONObject();
 myObj.put("JSON", "Hello, World!");
 myObj.write( myWriter );
 

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

The texts produced by the write 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).

Reading JSON Format

To read from a stream, reader, or string, use the following:

 JSONObject jo = new JSONObject( new JSONTokener( input ) );
 

To read from a file, it is most convenient:

 JSONObject jo = JSONObject.readFromFile( file );
 

Writing JSON Format

If you want to write to a stream, use the write methods on JSON object or array:

 jo.write( output );
 -or-
 jo.write( output, 2, 0 );
 

To write to a file. This is more than just a convenience, this will write to a temporary file, and then only when it is fully written, will delete the existing file, and rename the temp to the new name:

 jo.writeToFile( file );
 

Thus, no matter if the server crashes in the middle of writing, the file being pointed to will always contain valid JSON format contents. If the server crashes in the middle of writing, this may leave "temp" files in the file system.

If you have multiple programs running which will be updating a JSON file, please look into LockableJSONFile for proper file system level locking of JSON files.

See Also:

Originally written by JSON.org released 2012-10-26 but heavily modified by Keith Swenson in the years after that to make the object classes conform to style guidelines discussed in http://agiletribe.wordpress.com/

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(JSONObject jo, java.lang.String[] names) Construct a JSONObject from a subset of another JSONObject.
JSONObject(JSONTokener x) Construct a JSONObject from a JSONTokener.
JSONObject(java.lang.Object bean) Construct a JSONObject from an Object using bean getters.
JSONObject(java.lang.String source) Deprecated. don't use this, use the JSONTokener instead. The JSON stream should never be a string, but instead should always be a Stream. It is always more efficient to stream the JSON representation in and out. Never use a string for this.

Method Summary

Modifier and Type	Method and Description
JSONObject	accumulate(java.lang.String key, java.lang.Object value) Accumulate values under a key.
JSONObject	append(java.lang.String key, java.lang.Object value) Append values to the array under a key.
static java.lang.String	doubleToString(double d) Produce a string from a double.
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.
double	getDouble(java.lang.String key) Get the double value associated with a key.
int	getInt(java.lang.String key) Get the int value associated with a key.
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.
static java.lang.String[]	getNames(JSONObject jo) Get an array of field names from a JSONObject.
static java.lang.String[]	getNames(java.lang.Object object) Get an array of field names from an Object.
java.lang.String	getString(java.lang.String key) Get the string associated with a key.
boolean	has(java.lang.String key) Determine if the JSONObject contains a value at a specific key.
JSONObject	increment(java.lang.String key) Increment a property of a JSONObject.
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<java.lang.String>	keys() Deprecated. use keySet instead because iterators are old fashioned
java.util.Set<java.lang.String>	keySet()
int	length() Get the number of keys stored in the JSONObject.
JSONArray	names() Produce a JSONArray containing the names of the elements of this JSONObject.
static java.lang.String	numberToString(java.lang.Number number) Produce a string from a Number.
java.lang.Object	opt(java.lang.String key) Get an optional value associated with a key.
boolean	optBoolean(java.lang.String key) Get an optional boolean associated with a key.
boolean	optBoolean(java.lang.String key, boolean defaultValue) Get an optional boolean associated with a key.
double	optDouble(java.lang.String key) Get an optional double associated with a key, or NaN if there is no such key or if its value is not a number.
double	optDouble(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.
int	optInt(java.lang.String key) Get an optional int value associated with a key, or zero if there is no such key or if the value is not a number.
int	optInt(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	optJSONArray(java.lang.String key) Get an optional JSONArray associated with a key.
JSONObject	optJSONObject(java.lang.String key) Get an optional JSONObject associated with a key.
long	optLong(java.lang.String key) Get an optional long value associated with a key, or zero if there is no such key or if the value is not a number.
long	optLong(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	optString(java.lang.String key) Get an optional string associated with a key.
java.lang.String	optString(java.lang.String key, java.lang.String defaultValue) Get an optional string associated with a key.
JSONObject	put(java.lang.String key, boolean value) Put a key/boolean pair in the JSONObject.
JSONObject	put(java.lang.String key, java.util.Collection<?> value) Put a key/value pair in the JSONObject, where the value will be a JSONArray which is produced from a Collection.
JSONObject	put(java.lang.String key, double value) Put a key/double pair in the JSONObject.
JSONObject	put(java.lang.String key, int value) Put a key/int pair in the JSONObject.
JSONObject	put(java.lang.String key, long value) Put a key/long pair in the JSONObject.
JSONObject	put(java.lang.String key, java.util.Map<java.lang.String,?> value) Put a key/value pair in the JSONObject, where the value will be a JSONObject which is produced from a Map.
JSONObject	put(java.lang.String key, java.lang.Object value) Put a key/value pair in the JSONObject.
JSONObject	putOnce(java.lang.String key, java.lang.Object value) Put a key/value pair in the JSONObject, but only if the key and the value are both non-null, and only if there is not already a member with that name.
JSONObject	putOpt(java.lang.String key, java.lang.Object value) Put a key/value pair in the JSONObject, but only if the key and the value are both non-null.
static java.lang.String	quote(java.lang.String string) Produce a string in double quotes with all the characters that need it encoded properly.
static java.io.Writer	quote(java.lang.String string, java.io.Writer w) Writes a quoted (encoded) version of the string to the Writer, and returns the same writer that was passed in.
static JSONObject	readFileIfExists(java.io.File inFile) Open the file if exists, read the contents, and return the JSONObject tree that the file represents.
static JSONObject	readFromFile(java.io.File inFile) Open the file if exists, read the contents, and return the JSONObject tree that the file represents.
java.lang.Object	remove(java.lang.String key) Remove a name and its value, if present.
JSONArray	requireJSONArray(java.lang.String key) Get the JSONArray value associated with a key and create an empty array with that key if it does not yet exist.
JSONObject	requireJSONObject(java.lang.String key) Get the JSONObject value associated with a key, and create one if it does not exist yet.
java.util.Iterator<java.lang.String>	sortedKeys() Deprecated. use sortedKeySet instead because iterators are old fashioned
java.util.List<java.lang.String>	sortedKeySet()
static java.lang.Object	stringToValue(java.lang.String string) Try to convert a string into a number, boolean, or null.
static void	testValidity(java.lang.Object o) Throw an exception if the object is a NaN or infinite number.
JSONArray	toJSONArray(JSONArray names) Produce a JSONArray containing the values of the members of this JSONObject.
java.lang.String	toString() Make a JSON text of this JSONObject.
java.lang.String	toString(int indentFactor) Make a JSON text String representation of this JSONObject.
static java.lang.String	valueToString(java.lang.Object value) Make a JSON text of an Object value.
static java.lang.Object	wrap(java.lang.Object object) Wrap an object, if necessary.
java.io.Writer	write(java.io.Writer writer) Write the contents of the JSONObject as JSON text.
java.io.Writer	write(java.io.Writer writer, int indentFactor, int indent) Write the contents of the JSONObject as JSON text to a writer.
void	writeToFile(java.io.File outFile) Write the entire contents of the JSONObject tree to the specified file using JSON format.

Methods inherited from class java.lang.Object

clone, equals, finalize, 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(JSONObject jo,
                  java.lang.String[] names)
           throws java.lang.Exception

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.

names - An array of strings.

Throws:

JSONException

JSONException - If a value is a non-finite number or if a name is duplicated.

java.lang.Exception

JSONObject

public JSONObject(JSONTokener x)
           throws JSONException

Construct a JSONObject from a JSONTokener. This SHOULD be the most common constructor because it consumes a stream directly and builds the object in the most efficient manner.

For a UTF-8 encoded stream, use:
new JSONObject( new JSONTokener( inputStream ) );
For a character based reader, including inputStreams of other encodings wrapped in the appropriate InputStreamReader, use:
new JSONObject( new JSONTokener( reader ) );

Parameters:

x - A JSONTokener object containing the source string.

Throws:

JSONException - If there is a syntax error in the source string or a duplicated key.

JSONObject

public JSONObject(java.lang.Object bean)

Construct a JSONObject from an Object using bean getters. It reflects on all of the public methods of the object. For each of the methods with no parameters and a name starting with "get" or "is" followed by an uppercase letter, the method is invoked, and a key and the value returned from the getter method are put into the new JSONObject. The key is formed by removing the "get" or "is" prefix. If the second remaining character is not upper case, then the first character is converted to lower case. For example, if an object has a method named "getName", and if the result of calling object.getName() is "Larry Fine", then the JSONObject will contain "name": "Larry Fine".

Parameters:

bean - An object that has getter methods that should be used to make a JSONObject.

JSONObject

public JSONObject(java.lang.String source)
           throws JSONException

Deprecated. don't use this, use the JSONTokener instead. The JSON stream should never be a string, but instead should always be a Stream. It is always more efficient to stream the JSON representation in and out. Never use a string for this.

Construct a JSONObject from a source JSON text string.

Throws:

JSONException

Method Detail

readFromFile

public static JSONObject readFromFile(java.io.File inFile)
                               throws java.lang.Exception

Open the file if exists, read the contents, and return the JSONObject tree that the file represents.

Throws:

java.lang.Exception

readFileIfExists

public static JSONObject readFileIfExists(java.io.File inFile)
                                   throws java.lang.Exception

Open the file if exists, read the contents, and return the JSONObject tree that the file represents. If the file does not exist, then it return an empty JSONObject representing the content of the file that does not exist. This is useful for files that lazily created and that start as an empty JSONObject. This makes a missing file acts as if the file had been initialized with an empty JSONObject, but it does not actually update the file system with a new file.

Throws:

java.lang.Exception

writeToFile

public void writeToFile(java.io.File outFile)
                 throws java.lang.Exception

Write the entire contents of the JSONObject tree to the specified file using JSON format. This is written out properly and safely by first writing to a temporary file with the symbol ~tmp~ on the end, as well as a time stamp to ensure uniqueness. Then, once the temp file exists, the old file (if there was one) is deleted, and the temp file is renamed to be the desired output file name. This guarantees that you will Always have a complete file on the disk (along with a vanishingly small possibility that there will be no file). No matter if the host program crashes, or the power goes out, you will never have a half-written corrupted file on disk.

Parameters:

outFile -

Throws:

java.lang.Exception

accumulate

public JSONObject accumulate(java.lang.String key,
                             java.lang.Object value)
                      throws JSONException

Accumulate values under a key. It is similar to the put method except that if there is already an object stored under the key then a JSONArray is stored under the key to hold all of the accumulated values. If there is already a JSONArray, then the new value is appended to it. In contrast, the put method replaces the previous value. If only one value is accumulated that is not a JSONArray, then the result will be the same as using put. But if multiple values are accumulated, then the result will be like append.

Parameters:

key - A key string.

value - An object to be accumulated under the key.

Returns:

this.

Throws:

JSONException - If the value is an invalid number or if the key is null.

append

public JSONObject append(java.lang.String key,
                         java.lang.Object value)
                  throws JSONException

Append values to the array under a key. If the key does not exist in the JSONObject, then the key is put in the JSONObject with its value being a JSONArray containing the value parameter. If the key was already associated with a JSONArray, then the value parameter is appended to it.

Parameters:

key - A key string.

value - An object to be accumulated under the key.

Returns:

this.

Throws:

JSONException - If the key is null or if the current value associated with the key is not a JSONArray.

doubleToString

public static java.lang.String doubleToString(double d)

Produce a string from a double. The string "null" will be returned if the number is not finite.

Parameters:

d - A double.

Returns:

A String.

get

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

Get the value object associated with a key.

Parameters:

key - A key string.

Returns:

The object associated with the key.

Throws:

JSONException - if the key is not found.

getBoolean

public boolean getBoolean(java.lang.String key)
                   throws JSONException

Get the boolean value associated with a key.

Parameters:

key - A key string.

Returns:

The truth.

Throws:

JSONException - if the value is not a Boolean or the String "true" or "false".

getDouble

public double getDouble(java.lang.String key)
                 throws JSONException

Get the double value associated with a key.

Parameters:

key - A key string.

Returns:

The numeric value.

Throws:

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

getInt

public int getInt(java.lang.String key)
           throws JSONException

Get the int value associated with a key.

Parameters:

key - A key string.

Returns:

The integer value.

Throws:

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

getJSONArray

public JSONArray getJSONArray(java.lang.String key)
                       throws JSONException

Get the JSONArray value associated with a key.

Parameters:

key - A key string.

Returns:

A JSONArray which is the value.

Throws:

JSONException - if the key is not found or if the value is not a JSONArray.

requireJSONArray

public JSONArray requireJSONArray(java.lang.String key)
                           throws JSONException

Get the JSONArray value associated with a key and create an empty array with that key if it does not yet exist.

Parameters:

key - A key string.

Returns:

A JSONArray which is the value.

Throws:

JSONException - if the key exists but value is not a JSONArray.

getJSONObject

public JSONObject getJSONObject(java.lang.String key)
                         throws JSONException

Get the JSONObject value associated with a key.

Parameters:

key - A key string.

Returns:

A JSONObject which is the value.

Throws:

JSONException - if the key is not found or if the value is not a JSONObject.

requireJSONObject

public JSONObject requireJSONObject(java.lang.String key)
                             throws JSONException

Get the JSONObject value associated with a key, and create one if it does not exist yet.

Parameters:

key - A key string.

Returns:

A JSONObject which is the value.

Throws:

JSONException - if the key exists but is not a JSONObject.

getLong

public long getLong(java.lang.String key)
             throws JSONException

Get the long value associated with a key.

Parameters:

key - A key string.

Returns:

The long value.

Throws:

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

getNames

public static java.lang.String[] getNames(JSONObject jo)

Get an array of field names from a JSONObject.

Returns:

An array of field names. Never returns null. if there are no fields, returns an empty array.

getNames

public static java.lang.String[] getNames(java.lang.Object object)

Get an array of field names from an Object.

Returns:

An array of field names. Never returns null.

getString

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

Get the string associated with a key.

Parameters:

key - A key string.

Returns:

A string which is the value.

Throws:

JSONException - if there is no string value for the key.

has

public boolean has(java.lang.String key)

Determine if the JSONObject contains a value at a specific key. This is exactly the same as !isNull(key)

Parameters:

key - A key string.

Returns:

true if the key exists in the JSONObject AND points to a non-null value.

increment

public JSONObject increment(java.lang.String key)
                     throws JSONException

Increment a property of a JSONObject. If there is no such property, create one with a value of 1. If there is such a property, and if it is an Integer, Long, Double, or Float, then add one to it.

Parameters:

key - A key string.

Returns:

this.

Throws:

JSONException - If there is already a property with this name that is not an Integer, Long, Double, or Float.

isNull

public boolean isNull(java.lang.String key)

Determine if the value associated with the key is null or if there is no value. This is exactly the same as !has(key)

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.

keySet

public java.util.Set<java.lang.String> keySet()

Returns:

Return a set of keys of the JSONObject

sortedKeySet

public java.util.List<java.lang.String> sortedKeySet()

Returns:

Return a list of keys of the JSONObject in sorted order

sortedKeys

public java.util.Iterator<java.lang.String> sortedKeys()

Deprecated. use sortedKeySet instead because iterators are old fashioned

Don't use this, because it is an iterator. Deprecated. Use sortedKeySet instead which gives you the same functionality but as a List object which allows for the normal Java language capability to iterate automatically over it.

keys

public java.util.Iterator<java.lang.String> keys()

Deprecated. use keySet instead because iterators are old fashioned

Don't use this, because it is an iterator. Deprecated. Use keySet instead which gives you the same functionality but as a List object which allows for the normal Java language capability to iterate automatically over it. Also, consider using sortedKeySet if you are outputting this to an external destination because getting the keys in a predictable order can help in some other ways.

length

public int length()

Get the number of keys stored in the JSONObject.

Returns:

The number of keys in the JSONObject.

names

public JSONArray names()

Produce a JSONArray containing the names of the elements of this JSONObject. Never returns a null. If there are no keys, it returns an empty array.

Returns:

A JSONArray containing the key strings, or null if the JSONObject is empty.

numberToString

public static java.lang.String numberToString(java.lang.Number number)
                                       throws JSONException

Produce a string from a Number.

Parameters:

number - A Number

Returns:

A String.

Throws:

JSONException - If n is a non-finite number.

opt

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

Get an optional value associated with a key. Returns a null if you pass in a null, or if there is no value at the specified key.

Parameters:

key - A key string.

Returns:

An object which is the value, or null if there is no value.

optBoolean

public boolean optBoolean(java.lang.String key)

Get an optional boolean associated with a key. It returns false if there is no such key, or if the value is not Boolean.TRUE or the String "true".

Parameters:

key - A key string.

Returns:

The truth.

optBoolean

public boolean optBoolean(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.

optDouble

public double optDouble(java.lang.String key)

Get an optional double associated with a key, or NaN 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 string which is the key.

Returns:

An object which is the value.

optDouble

public double optDouble(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.

optInt

public int optInt(java.lang.String key)

Get an optional int value associated with a key, or zero 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.

Returns:

An object which is the value.

optInt

public int optInt(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.

optJSONArray

public JSONArray optJSONArray(java.lang.String key)

Get an optional JSONArray associated with a key. It returns null if there is no such key, or if its value is not a JSONArray.

Parameters:

key - A key string.

Returns:

A JSONArray which is the value.

optJSONObject

public JSONObject optJSONObject(java.lang.String key)

Get an optional JSONObject associated with a key. It returns null if there is no such key, or if its value is not a JSONObject.

Parameters:

key - A key string.

Returns:

A JSONObject which is the value.

optLong

public long optLong(java.lang.String key)

Get an optional long value associated with a key, or zero 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.

Returns:

An object which is the value.

optLong

public long optLong(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.

optString

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

Get an optional string associated with a key. It returns an empty string if there is no such key. If the value is not a string and is not null, then it is converted to a string.

Parameters:

key - A key string.

Returns:

A string which is the value.

optString

public java.lang.String optString(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.

put

public JSONObject put(java.lang.String key,
                      boolean value)
               throws JSONException

Put a key/boolean pair in the JSONObject.

Parameters:

key - A key string.

value - A boolean which is the value.

Returns:

this.

Throws:

JSONException - If the key is null.

put

public JSONObject put(java.lang.String key,
                      java.util.Collection<?> value)
               throws JSONException

Put a key/value pair in the JSONObject, where the value will be a JSONArray which is produced from a Collection.

Parameters:

key - A key string.

value - A Collection value.

Returns:

this.

Throws:

JSONException

put

public JSONObject put(java.lang.String key,
                      double value)
               throws JSONException

Put a key/double pair in the JSONObject.

Parameters:

key - A key string.

value - A double which is the value.

Returns:

this.

Throws:

JSONException - If the key is null or if the number is invalid.

put

public JSONObject put(java.lang.String key,
                      int value)
               throws JSONException

Put a key/int pair in the JSONObject.

Parameters:

key - A key string.

value - An int which is the value.

Returns:

this.

Throws:

JSONException - If the key is null.

put

public JSONObject put(java.lang.String key,
                      long value)
               throws JSONException

Put a key/long pair in the JSONObject.

Parameters:

key - A key string.

value - A long which is the value.

Returns:

this.

Throws:

JSONException - If the key is null.

put

public JSONObject put(java.lang.String key,
                      java.util.Map<java.lang.String,?> value)
               throws JSONException

Put a key/value pair in the JSONObject, where the value will be a JSONObject which is produced from a Map.

Parameters:

key - A key string.

value - A Map value.

Returns:

this.

Throws:

JSONException

put

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

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:

JSONException - If the value is non-finite number or if the key is null.

putOnce

public JSONObject putOnce(java.lang.String key,
                          java.lang.Object value)
                   throws JSONException

Put a key/value pair in the JSONObject, but only if the key and the value are both non-null, and only if there is not already a member with that name.

Parameters:

key -

value -

Returns:

his.

Throws:

JSONException - if the key is a duplicate

putOpt

public JSONObject putOpt(java.lang.String key,
                         java.lang.Object value)
                  throws JSONException

Put a key/value pair in the JSONObject, but only if the key and the value are both non-null. If either the key or the value is null, then simply do nothing.

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:

JSONException - If the value is a non-finite number.

quote

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

Produce a string in double quotes with all the characters that need it encoded properly. See quote. This method uses that stream-based quote method. Consider using that if you are simply going to write the string out someplace.

Parameters:

string - the string value you want to be encoded.

Returns:

That value correctly encoded 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

Writes a quoted (encoded) version of the string to the Writer, and returns the same writer that was passed in. That is, it writes double quote characters before and after the value, and then scans the value, putting a backslash before each double quote, and before each backslash. It also converts newlines, returns, tabs, linefeed, and backspace characters to their properly encoded symbolic equivalent.

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.

stringToValue

public static java.lang.Object stringToValue(java.lang.String string)

Try to convert a string into a number, boolean, or null. If the string can't be converted, return the string.

Parameters:

string - A String.

Returns:

A simple JSON value.

testValidity

public static void testValidity(java.lang.Object o)
                         throws JSONException

Throw an exception if the object is a NaN or infinite number.

Parameters:

o - The object to test.

Throws:

JSONException - If o is a non-finite number.

toJSONArray

public JSONArray toJSONArray(JSONArray names)
                      throws JSONException

Produce a JSONArray containing the values of the members of this JSONObject.

Parameters:

names - A JSONArray containing a list of key strings. This determines the sequence of the values in the result.

Returns:

A JSONArray of values.

Throws:

JSONException - If any of the values are non-finite numbers.

toString

public java.lang.String toString()

Make a JSON text of this JSONObject. For compactness, no whitespace is added. If this would not result in a syntactically correct JSON text, or if there is an exception for any other reason, then null will be returned instead.

Think carefully before using this method! Do you really need a String in memory? Since JSON is used as a data transport format normally you are going to write the String out to some destination. It is far more efficient to use the write operation on this object directly. Think about it: you have a tree of JSON objects in memory. This method will make a copy of all that data into a single string -- a second copy of the data in memory. If all you are going to do is to write that string out to a file, then use the write method to stream it directly to the file. If you are going to send the data from a server to client browser, the write directly to the output stream. This reduces memory usage. Sometimes you really do need a String, so the method is provided, but use it sparingly.

Warning: This method assumes that the data structure is acyclical.

Overrides:

toString in class java.lang.Object

Returns:

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

toString

public java.lang.String toString(int indentFactor)

Make a JSON text String representation of this JSONObject. Think carefully before using this method! Do you really need a String in memory? Since JSON is used as a data transport format normally you are going to write the String out to some destination. It is far more efficient to use the write operation on this object directly. Think about it: you have a tree of JSON objects in memory. This method will make a copy of all that data into a single string -- a second copy of the data in memory. If all you are going to do is to write that string out to a file, then use the write method to stream it directly to the file. If you are going to send the data from a server to client browser, the write directly to the output stream. This reduces memory usage. Sometimes you really do need a String, so the method is provided, but use it sparingly.

The JSON is produced indented by an indentFactor amount specified. If you specify zero indent, the output will be all on a single line. The elements are alphabetized only if an indent is specified.

Warning: This method assumes that the data structure is acyclical. An exception will be thrown if you have a cycle.

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:

JSONException - If the object contains an invalid number.

valueToString

public static java.lang.String valueToString(java.lang.Object value)
                                      throws JSONException

Make a JSON text of an Object value. If the object has an value.toJSONString() method, then that method will be used to produce the JSON text. The method is required to produce a strictly conforming text. If the object does not contain a toJSONString method (which is the most common case), then a text will be produced by other means. If the value is an array or Collection, then a JSONArray will be made from it and its toJSONString method will be called. If the value is a MAP, then a JSONObject will be made from it and its toJSONString method will be called. Otherwise, the value's toString method will be called, and the result will be quoted.

Warning: This method assumes that the data structure is acyclical.

Parameters:

value - The value to be serialized.

Returns:

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

Throws:

JSONException - If the value is or contains an invalid number.

wrap

public static java.lang.Object wrap(java.lang.Object object)

Wrap an object, if necessary. If the object is null, return the NULL object. If it is an array or collection, wrap it in a JSONArray. If it is a map, wrap it in a JSONObject. If it is a standard property (Double, String, et al) then it is already wrapped. Otherwise, if it comes from one of the java packages, turn it into a string. And if it doesn't, try to wrap it in a JSONObject. If the wrapping fails, then null is returned.

Parameters:

object - The object to wrap

Returns:

The wrapped value

write

public java.io.Writer write(java.io.Writer writer)
                     throws JSONException

Write the contents of the JSONObject as JSON text. No indentation.

Warning: This method assumes that the data structure is acyclical.

Returns:

The writer.

Throws:

JSONException

write

public java.io.Writer write(java.io.Writer writer,
                            int indentFactor,
                            int indent)
                     throws JSONException

Write the contents of the JSONObject as JSON text to a writer. values are put with name/value on a line. Collections are indented to show the level of nesting. Keys are written in alphabetical order so that the same document is produced with a given set of values regardless of what order it was constructed. The order of arrays are preserved.

Standard usage: jobj.write( writer, 2, 0 );

Warning: This method will abort if the indent level exceeds 100 because that probably indicates that the JSON is linked in a loop.

Parameters:

writer - where the output goes to

indentFactor - specify the number of spaces for each level of nesting. A value of 2 will indent two spaces for each level of indent.

indent - should be set to zero for the root most level when you start the writing of a JSON document. This method is called recursively and this parameter indicates the level of recursion.

Returns:

The writer that was passed in

Throws:

JSONException