JSONArray

AI-generated Key Takeaways

• JSONArray is an ordered list of values used to represent JSON data, accommodating various data types including other JSONArrays and JSONObjects.

• It offers methods for data retrieval (get, opt), manipulation (put, remove), conversion (toJSONObject), and output (toString) to interact with JSON data structures.

• JSONArray is not thread-safe, requiring careful handling in concurrent environments to avoid data corruption.

• JSONArray handles null values using both Java's null and JSONObject.NULL, and provides methods like isNull and opt for safe null value handling.

• While primarily used for data representation, JSONArray provides utility methods for string joining (join) and comparison (equals, hashCode).

public class JSONArray extends Object

A dense indexed sequence of values. Values may be any mix of JSONObjects, other JSONArrays, Strings, Booleans, Integers, Longs, Doubles, null or JSONObject.NULL. Values may not be NaNs, infinities, or of any type not listed here.

JSONArray has the same type coercion behavior and optional/mandatory accessors as JSONObject. See that class' documentation for details.

Warning: this class represents null in two incompatible ways: the standard Java null reference, and the sentinel value JSONObject.NULL. In particular, get fails if the requested index holds the null reference, but succeeds if it holds JSONObject.NULL.

Instances of this class are not thread safe. Although this class is nonfinal, it was not designed for inheritance and should not be subclassed. In particular, self-use by overridable methods is not specified. See Effective Java Item 17, "Design and Document or inheritance or else prohibit it" for further information.

Public Constructor Summary

	JSONArray() Creates a JSONArray with no values.
	JSONArray(Collection copyFrom) Creates a new JSONArray by copying all values from the given collection.
	JSONArray(JSONTokener readFrom) Creates a new JSONArray with values from the next array in the tokener.
	JSONArray(String json) Creates a new JSONArray with values from the JSON string.
	JSONArray(Object array) Creates a new JSONArray with values from the given primitive array.

Public Method Summary

boolean	equals(Object o)
Object	get(int index) Returns the value at index.
boolean	getBoolean(int index) Returns the value at index if it exists and is a boolean or can be coerced to a boolean.
double	getDouble(int index) Returns the value at index if it exists and is a double or can be coerced to a double.
int	getInt(int index) Returns the value at index if it exists and is an int or can be coerced to an int.
JSONArray	getJSONArray(int index) Returns the value at index if it exists and is a JSONArray.
JSONObject	getJSONObject(int index) Returns the value at index if it exists and is a JSONObject.
long	getLong(int index) Returns the value at index if it exists and is a long or can be coerced to a long.
String	getString(int index) Returns the value at index if it exists, coercing it if necessary.
int	hashCode()
boolean	isNull(int index) Returns true if this array has no value at index, or if its value is the null reference or JSONObject.NULL.
String	join(String separator) Returns a new string by alternating this array's values with separator.
int	length() Returns the number of values in this array.
Object	opt(int index) Returns the value at index, or null if the array has no value at index.
boolean	optBoolean(int index) Returns the value at index if it exists and is a boolean or can be coerced to a boolean.
boolean	optBoolean(int index, boolean fallback) Returns the value at index if it exists and is a boolean or can be coerced to a boolean.
double	optDouble(int index) Returns the value at index if it exists and is a double or can be coerced to a double.
double	optDouble(int index, double fallback) Returns the value at index if it exists and is a double or can be coerced to a double.
int	optInt(int index) Returns the value at index if it exists and is an int or can be coerced to an int.
int	optInt(int index, int fallback) Returns the value at index if it exists and is an int or can be coerced to an int.
JSONArray	optJSONArray(int index) Returns the value at index if it exists and is a JSONArray.
JSONObject	optJSONObject(int index) Returns the value at index if it exists and is a JSONObject.
long	optLong(int index) Returns the value at index if it exists and is a long or can be coerced to a long.
long	optLong(int index, long fallback) Returns the value at index if it exists and is a long or can be coerced to a long.
String	optString(int index) Returns the value at index if it exists, coercing it if necessary.
String	optString(int index, String fallback) Returns the value at index if it exists, coercing it if necessary.
JSONArray	put(int value) Appends value to the end of this array.
JSONArray	put(long value) Appends value to the end of this array.
JSONArray	put(int index, boolean value) Sets the value at index to value, null padding this array to the required length if necessary.
JSONArray	put(double value) Appends value to the end of this array.
JSONArray	put(int index, Object value) Sets the value at index to value, null padding this array to the required length if necessary.
JSONArray	put(int index, long value) Sets the value at index to value, null padding this array to the required length if necessary.
JSONArray	put(int index, int value) Sets the value at index to value, null padding this array to the required length if necessary.
JSONArray	put(boolean value) Appends value to the end of this array.
JSONArray	put(int index, double value) Sets the value at index to value, null padding this array to the required length if necessary.
JSONArray	put(Object value) Appends value to the end of this array.
Object	remove(int index) Removes and returns the value at index, or null if the array has no value at index.
JSONObject	toJSONObject(JSONArray names) Returns a new object whose values are the values in this array, and whose names are the values in names.
String	toString() Encodes this array as a compact JSON string, such as: [94043,90210]
String	toString(int indentSpaces) Encodes this array as a human readable JSON string for debugging, such as: [ 94043, 90210 ]

Inherited Method Summary

From class java.lang.Object

Object	clone()
boolean	equals(Object arg0)
void	finalize()
final Class<?>	getClass()
int	hashCode()
final void	notify()
final void	notifyAll()
String	toString()
final void	wait(long arg0, int arg1)
final void	wait(long arg0)
final void	wait()

Public Constructors

public JSONArray ()

Creates a JSONArray with no values.

public JSONArray (Collection copyFrom)

Creates a new JSONArray by copying all values from the given collection.

Parameters

copyFrom	a collection whose values are of supported types. Unsupported values are not permitted and will yield an array in an inconsistent state.

public JSONArray (JSONTokener readFrom)

Creates a new JSONArray with values from the next array in the tokener.

Parameters

readFrom	a tokener whose nextValue() method will yield a JSONArray.

Throws

JSONException	if the parse fails or doesn't yield a JSONArray.

public JSONArray (String json)

Creates a new JSONArray with values from the JSON string.

Parameters

json	a JSON-encoded string containing an array.

Throws

JSONException	if the parse fails or doesn't yield a JSONArray.

public JSONArray (Object array)

Creates a new JSONArray with values from the given primitive array.

Parameters

array

Throws

JSONException

Public Methods

public boolean equals (Object o)

Parameters

o

public Object get (int index)

Returns the value at index.

Parameters

index

Throws

JSONException	if this array has no value at index, or if that value is the null reference. This method returns normally if the value is JSONObject#NULL.

public boolean getBoolean (int index)

Returns the value at index if it exists and is a boolean or can be coerced to a boolean.

Parameters

index

Throws

JSONException	if the value at index doesn't exist or cannot be coerced to a boolean.

public double getDouble (int index)

Returns the value at index if it exists and is a double or can be coerced to a double.

Parameters

index

Throws

JSONException	if the value at index doesn't exist or cannot be coerced to a double.

public int getInt (int index)

Returns the value at index if it exists and is an int or can be coerced to an int.

Parameters

index

Throws

JSONException	if the value at index doesn't exist or cannot be coerced to a int.

public JSONArray getJSONArray (int index)

Returns the value at index if it exists and is a JSONArray.

Parameters

index

Throws

JSONException	if the value doesn't exist or is not a JSONArray.

public JSONObject getJSONObject (int index)

Returns the value at index if it exists and is a JSONObject.

Parameters

index

Throws

JSONException	if the value doesn't exist or is not a JSONObject.

public long getLong (int index)

Returns the value at index if it exists and is a long or can be coerced to a long.

Parameters

index

Throws

JSONException	if the value at index doesn't exist or cannot be coerced to a long.

public String getString (int index)

Returns the value at index if it exists, coercing it if necessary.

Parameters

index

Throws

JSONException	if no such value exists.

public int hashCode ()

public boolean isNull (int index)

Returns true if this array has no value at index, or if its value is the null reference or JSONObject.NULL.

Parameters

index

public String join (String separator)

Returns a new string by alternating this array's values with separator. This array's string values are quoted and have their special characters escaped. For example, the array containing the strings '12" pizza', 'taco' and 'soda' joined on '+' returns this:

"12\" pizza"+"taco"+"soda"

Parameters

separator

Throws

JSONException

public int length ()

Returns the number of values in this array.

public Object opt (int index)

Returns the value at index, or null if the array has no value at index.

Parameters

index

public boolean optBoolean (int index)

Returns the value at index if it exists and is a boolean or can be coerced to a boolean. Returns false otherwise.

Parameters

index

public boolean optBoolean (int index, boolean fallback)

Returns the value at index if it exists and is a boolean or can be coerced to a boolean. Returns fallback otherwise.

Parameters

index
fallback

public double optDouble (int index)

Returns the value at index if it exists and is a double or can be coerced to a double. Returns NaN otherwise.

Parameters

index

public double optDouble (int index, double fallback)

Returns the value at index if it exists and is a double or can be coerced to a double. Returns fallback otherwise.

Parameters

index
fallback

public int optInt (int index)

Returns the value at index if it exists and is an int or can be coerced to an int. Returns 0 otherwise.

Parameters

index

public int optInt (int index, int fallback)

Returns the value at index if it exists and is an int or can be coerced to an int. Returns fallback otherwise.

Parameters

index
fallback

public JSONArray optJSONArray (int index)

Returns the value at index if it exists and is a JSONArray. Returns null otherwise.

Parameters

index

public JSONObject optJSONObject (int index)

Returns the value at index if it exists and is a JSONObject. Returns null otherwise.

Parameters

index

public long optLong (int index)

Returns the value at index if it exists and is a long or can be coerced to a long. Returns 0 otherwise.

Parameters

index

public long optLong (int index, long fallback)

Returns the value at index if it exists and is a long or can be coerced to a long. Returns fallback otherwise.

Parameters

index
fallback

public String optString (int index)

Returns the value at index if it exists, coercing it if necessary. Returns the empty string if no such value exists.

Parameters

index

public String optString (int index, String fallback)

Returns the value at index if it exists, coercing it if necessary. Returns fallback if no such value exists.

Parameters

index
fallback

public JSONArray put (int value)

Appends value to the end of this array.

Parameters

value

Returns

• this array.

public JSONArray put (long value)

Appends value to the end of this array.

Parameters

value

Returns

• this array.

public JSONArray put (int index, boolean value)

Sets the value at index to value, null padding this array to the required length if necessary. If a value already exists at index, it will be replaced.

Parameters

index
value

Returns

• this array.

Throws

JSONException

public JSONArray put (double value)

Appends value to the end of this array.

Parameters

value	a finite value. May not be NaNs or infinities.

Returns

• this array.

Throws

JSONException

public JSONArray put (int index, Object value)

Sets the value at index to value, null padding this array to the required length if necessary. If a value already exists at index, it will be replaced.

Parameters

index
value	a JSONObject, JSONArray, String, Boolean, Integer, Long, Double, JSONObject.NULL, or null. May not be NaNs or infinities.

Returns

• this array.

Throws

JSONException

public JSONArray put (int index, long value)

Sets the value at index to value, null padding this array to the required length if necessary. If a value already exists at index, it will be replaced.

Parameters

index
value

Returns

• this array.

Throws

JSONException

public JSONArray put (int index, int value)

Sets the value at index to value, null padding this array to the required length if necessary. If a value already exists at index, it will be replaced.

Parameters

index
value

Returns

• this array.

Throws

JSONException

public JSONArray put (boolean value)

Appends value to the end of this array.

Parameters

value

Returns

• this array.

public JSONArray put (int index, double value)

Sets the value at index to value, null padding this array to the required length if necessary. If a value already exists at index, it will be replaced.

Parameters

index
value	a finite value. May not be NaNs or infinities.

Returns

• this array.

Throws

JSONException

public JSONArray put (Object value)

Appends value to the end of this array.

Parameters

value	a JSONObject, JSONArray, String, Boolean, Integer, Long, Double, JSONObject.NULL, or null. May not be NaNs or infinities. Unsupported values are not permitted and will cause the array to be in an inconsistent state.

Returns

• this array.

public Object remove (int index)

Removes and returns the value at index, or null if the array has no value at index.

Parameters

index

public JSONObject toJSONObject (JSONArray names)

Returns a new object whose values are the values in this array, and whose names are the values in names. Names and values are paired up by index from 0 through to the shorter array's length. Names that are not strings will be coerced to strings. This method returns null if either array is empty.

Parameters

names

Throws

JSONException

public String toString ()

Encodes this array as a compact JSON string, such as:

[94043,90210]

public String toString (int indentSpaces)

Encodes this array as a human readable JSON string for debugging, such as:

 [
     94043,
     90210
 ]

Parameters

indentSpaces	the number of spaces to indent for each level of nesting.

Throws

JSONException