com.iijgio.dag.util.json

Class JSONArray

java.lang.Object

com.iijgio.dag.util.json.JSONArray

public 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 coercion 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 0x- (hex) prefix.

Version:

2010 -12-28

Constructor Summary

Constructors

Constructor and Description
JSONArray() Construct an empty JSONArray.
JSONArray(Collection collection) Construct a JSONArray from a Collection.
JSONArray(JSONTokener x) Construct a JSONArray from a JSONTokener.
JSONArray(Object array) Construct a JSONArray from an array
JSONArray(String source) Construct a JSONArray from a source JSON text.

Method Summary

Modifier and Type	Method and Description
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.
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.
long	optLong(int index) Get the optional long value associated with an index.
long	optLong(int index, long defaultValue) Get the optional long value associated with an index.
String	optString(int index) Get the optional string value associated with an index.
String	optString(int index, String defaultValue) Get the optional string associated with an index.
JSONArray	put(boolean value) Append a boolean value.
JSONArray	put(Collection value) Put a value in the JSONArray, where the value will be a JSONArray which is produced from a Collection.
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, Collection value) Put a value in the JSONArray, where the value will be a JSONArray which is produced from a Collection.
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, long value) Put or replace a long value.
JSONArray	put(int index, Map value) Put a value in the JSONArray, where the value will be a JSONObject which is produced from a Map.
JSONArray	put(int index, Object value) Put or replace an object value in the JSONArray.
JSONArray	put(long value) Append an long value.
JSONArray	put(Map value) Put a value in the JSONArray, where the value will be a JSONObject which is produced from a Map.
JSONArray	put(Object value) Append an object value.
Object	remove(int index) Remove an index and close the hole.
JSONObject	toJSONObject(JSONArray names) Produce a JSONObject by combining a JSONArray of names with the values of this JSONArray.
String	toString() Make a JSON text of this JSONArray.
String	toString(int indentFactor) Make a prettyprinted JSON text of this JSONArray.
Writer	write(Writer writer) Write the contents of the JSONArray as JSON text to a writer.

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 JSONException

Construct a JSONArray from a JSONTokener.

Parameters:

x - A JSONTokener

Throws:

JSONException - If there is a syntax error.

JSONArray

public JSONArray(String source)
          throws JSONException

Construct a JSONArray from a source JSON text.

Parameters:

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

Throws:

JSONException - If there is a syntax error.

JSONArray

public JSONArray(Collection collection)

Construct a JSONArray from a Collection.

Parameters:

collection - A Collection.

JSONArray

public JSONArray(Object array)
          throws JSONException

Construct a JSONArray from an array

Parameters:

array - the array

Throws:

JSONException - If not an array.

Method Detail

get

public Object get(int index)
           throws JSONException

Get the object value associated with an index.

Parameters:

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

Returns:

An object value.

Throws:

JSONException - If there is no value for the index.

getBoolean

public boolean getBoolean(int index)
                   throws JSONException

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:

JSONException - If there is no value for the index or if the value is not convertible to boolean.

getDouble

public double getDouble(int index)
                 throws JSONException

Get the double value associated with an index.

Parameters:

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

Returns:

The value.

Throws:

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

getInt

public int getInt(int index)
           throws JSONException

Get the int value associated with an index.

Parameters:

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

Returns:

The value.

Throws:

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

getJSONArray

public JSONArray getJSONArray(int index)
                       throws JSONException

Get the JSONArray associated with an index.

Parameters:

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

Returns:

A JSONArray value.

Throws:

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

getJSONObject

public JSONObject getJSONObject(int index)
                         throws JSONException

Get the JSONObject associated with an index.

Parameters:

index - subscript

Returns:

A JSONObject value.

Throws:

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

getLong

public long getLong(int index)
             throws JSONException

Get the long value associated with an index.

Parameters:

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

Returns:

The value.

Throws:

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

getString

public String getString(int index)
                 throws JSONException

Get the string associated with an index.

Parameters:

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

Returns:

A string value.

Throws:

JSONException - 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)
            throws JSONException

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:

JSONException - 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).

opt

public 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 there is no value for the index, 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 there is no value for the index, 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 there is no value for the index, 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 there is no value for the index, 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.

optLong

public long optLong(int index)

Get the optional long value associated with an index. Zero is returned if there is no value for the index, 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.

optLong

public long optLong(int index,
                    long defaultValue)

Get the optional long value associated with an index. The defaultValue is returned if there is no value for the index, 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.

optString

public 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 String optString(int index,
                        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. This increases the array's length by one.

Parameters:

value - A boolean value.

Returns:

this. json array

put

public JSONArray put(Collection value)

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

Parameters:

value - A Collection value.

Returns:

this. json array

put

public JSONArray put(double value)
              throws JSONException

Append a double value. This increases the array's length by one.

Parameters:

value - A double value.

Returns:

this. json array

Throws:

JSONException - if the value is not finite.

put

public JSONArray put(int value)

Append an int value. This increases the array's length by one.

Parameters:

value - An int value.

Returns:

this. json array

put

public JSONArray put(long value)

Append an long value. This increases the array's length by one.

Parameters:

value - A long value.

Returns:

this. json array

put

public JSONArray put(Map value)

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

Parameters:

value - A Map value.

Returns:

this. json array

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:

this. json array

put

public JSONArray put(int index,
                     boolean value)
              throws JSONException

Put or replace a boolean 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 - A boolean value.

Returns:

this. json array

Throws:

JSONException - If the index is negative.

put

public JSONArray put(int index,
                     Collection value)
              throws JSONException

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

Parameters:

index - The subscript.

value - A Collection value.

Returns:

this. json array

Throws:

JSONException - If the index is negative or if the value is not finite.

put

public JSONArray put(int index,
                     double value)
              throws JSONException

Put or replace a double value. 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 - A double value.

Returns:

this. json array

Throws:

JSONException - If the index is negative or if the value is not finite.

put

public JSONArray put(int index,
                     int value)
              throws JSONException

Put or replace an int value. 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 - An int value.

Returns:

this. json array

Throws:

JSONException - If the index is negative.

put

public JSONArray put(int index,
                     long value)
              throws JSONException

Put or replace a long value. 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 - A long value.

Returns:

this. json array

Throws:

JSONException - If the index is negative.

put

public JSONArray put(int index,
                     Map value)
              throws JSONException

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

Parameters:

index - The subscript.

value - The Map value.

Returns:

this. json array

Throws:

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

put

public JSONArray put(int index,
                     Object value)
              throws JSONException

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:

this. json array

Throws:

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

remove

public Object remove(int index)

Remove an index and close the hole.

Parameters:

index - The index of the element to be removed.

Returns:

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

toJSONObject

public JSONObject toJSONObject(JSONArray names)
                        throws JSONException

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.

Throws:

JSONException - If any of the names are null.

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.

toString

public String toString(int indentFactor)
                throws JSONException

Make a prettyprinted JSON text of this JSONArray. 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, transmittable representation of the object, beginning with [ (left bracket) and ending with ] (right bracket).

Throws:

JSONException - the json exception

write

public Writer write(Writer writer)
             throws JSONException

Write the contents of the JSONArray as JSON text to a writer. For compactness, no whitespace is added.

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

Parameters:

writer - the writer

Returns:

The writer.

Throws:

JSONException - the json exception