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# JavaArray

A wrapped Java array accessed from within JavaScript code is a member of the type `JavaArray`.

Core object |
Implemented in | JavaScript 1.1, NES 2.0

#### 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`. 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. 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 Client-Side JavaScript Guide for more information about data type conversions.

#### Property Summary

Property | Description
--- | ---
    length
| The number of elements in the Java array represented by `JavaArray`.

#### Method Summary

Method | Description
--- | ---
    toString
| Returns a string identifying the object as a `JavaArray`.

#### 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. 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.

Property of | `JavaArray`
Implemented in | JavaScript 1.1, NES 2.0

#### 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.

Method of | `JavaArray`
Implemented in | JavaScript 1.1, NES 2.0

#### Parameters

None

#### Description

The `toString` method is inherited from the `Object` object and returns the following value:

    [object JavaArray]

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Last Updated: 05/28/99 11:59:40

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