JavaArray
A wrapped
Java array accessed from within JavaScript code is a member of the type
JavaArray.
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Core object
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Implemented in
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JavaScript 1.1, NES 2.0
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Created by
Any Java
method which returns an array. In addition, you can create a
JavaArray
with an arbitrary data type using the newInstance method
of the Array class:
public static Object newInstance(Class
componentType,
int length)
throws NegativeArraySizeException
Description
The
JavaArray
object is an instance of a Java array that is created in or passed to
JavaScript. JavaArray is a wrapper
for the instance; all references to the array instance are made through
the JavaArray.
In
JavaScript 1.4 and later, the componentType parameter
is either a JavaClass object
representing the type of the array or class object, such as one
returned by java.lang.Class.forName.
In JavaScript 1.3 and earlier, componentType must be a
class object.
Use
zero-based indexes to access the elements in a JavaArray object, just as
you do to access elements in an array in Java. For example:
var
javaString = new java.lang.String("Hello world!");
var byteArray = javaString.getBytes();
byteArray[0] // returns 72
byteArray[1] // returns 101
Any Java
data brought into JavaScript is converted to JavaScript data types.
When the JavaArray is passed back
to Java, the array is unwrapped and can be used by Java code. See the
Core
JavaScript Guide for more information about data type
conversions.
In
JavaScript 1.4 and later, the methods of java.lang.Object are
inherited by JavaArray.
Backward compatibility
JavaScript 1.3 and earlier.
The
methods of java.lang.Object are not
inherited by JavaArray. In addition,
the toString
method is inherited from the Object object and returns
the following value:
[object JavaArray]
You must
specify a class object, such as one returned by java.lang.Object.forName,
for the componentType parameter
of newInstance
when you use this method to create an array. You cannot use a
JavaClass
object for the componentType parameter.
Property
Summary
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Property
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Description
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length
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The
number of elements in the Java array represented by
JavaArray.
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Method Summary
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Method
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Description
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toString
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In
JavaScript 1.4, this method is overridden by the inherited method
java.lang.Object.toString.
In
JavaScript 1.3 and earlier, this method returns a string
identifying the object as a JavaArray.
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In
JavaScript 1.4 and later, JavaArray also inherits
methods from the Java array superclass, java.lang.Object.
Examples
Example
1. Instantiating a JavaArray in JavaScript.
In this
example, the JavaArray
byteArray
is created by the java.lang.String.getBytes
method, which returns an array.
var
javaString = new java.lang.String("Hello world!");
var byteArray = javaString.getBytes();
Example
2. Instantiating a JavaArray in JavaScript
with the newInstance method.
In
JavaScript 1.4, you can use a JavaClass object as the
argument for the newInstance method which
creates the array, as shown in the following code:
var
dogs = java.lang.reflect.Array.newInstance(java.lang.String, 5)
In
JavaScript 1.1, use a class object returned by java.lang.Class.forName
as the argument for the newInstance method, as
shown in the following code:
var
dataType = java.lang.Class.forName("java.lang.String")
var dogs = java.lang.reflect.Array.newInstance(dataType, 5)
length
The number
of elements in the Java array represented by the JavaArray
object.
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Property of
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JavaArray
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Implemented in
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JavaScript 1.1, NES 2.0
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Description
Unlike
Array.length,
JavaArray.length is a
read-only property. You cannot change the value of the
JavaArray.length
property because Java arrays have a fixed number of elements.
See also
Array.length
toString
Returns a
string representation of the JavaArray.
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Method of
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JavaArray
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Implemented in
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JavaScript 1.1, NES 2.0
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Parameters
None
Description
Calls the
method java.lang.Object.toString,
which returns the value of the following expression:
JavaArray.getClass().getName() + '@' +
java.lang.Integer.toHexString(JavaArray.hashCode())
Backward compatibility
JavaScript 1.3 and earlier.
The
toString
method is inherited from the Object object and returns
the following value:
[object JavaArray]
