array.java

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/*
 * @(#)Array.java	1.14 03/01/23
 *
 * Copyright 2003 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package java.lang.reflect;

/**
 * The <code>Array</code> class provides static methods to dynamically create and
 * access Java arrays.
 *
 * <p><code>Array</code> permits widening conversions to occur during a get or set
 * operation, but throws an <code>IllegalArgumentException</code> if a narrowing
 * conversion would occur.
 *
 * @author Nakul Saraiya
 */
public final
class Array {

    /**
     * Constructor.  Class Array is not instantiable.
     */
    private Array() {}

    /**
     * Creates a new array with the specified component type and
     * length.
     * Invoking this method is equivalent to creating an array
     * as follows:
     * <blockquote>
     * <pre>
     * int[] x = {length};
     * Array.newInstance(componentType, x);
     * </pre>
     * </blockquote>
     *
     * @param componentType the <code>Class</code> object representing the
     * component type of the new array
     * @param length the length of the new array
     * @return the new array
     * @exception NullPointerException if the specified
     * <code>componentType</code> parameter is null
     * @exception IllegalArgumentException if componentType is Void.TYPE
     * @exception NegativeArraySizeException if the specified <code>length</code> 
     * is negative
     */
    public static Object newInstance(Class componentType, int length)
	throws NegativeArraySizeException {
	return newArray(componentType, length);
    }

    /**
     * Creates a new array
     * with the specified component type and dimensions. 
     * If <code>componentType</code>
     * represents a non-array class or interface, the new array
     * has <code>dimensions.length</code> dimensions and&nbsp;
     * <code>componentType&nbsp;</code> as its component type. If
     * <code>componentType</code> represents an array class, the
     * number of dimensions of the new array is equal to the sum
     * of <code>dimensions.length</code> and the number of
     * dimensions of <code>componentType</code>. In this case, the
     * component type of the new array is the component type of
     * <code>componentType</code>.
     * 
     * <p>The number of dimensions of the new array must not
     * exceed the number of array dimensions supported by the
     * implementation (typically 255).
     *
     * @param componentType the <code>Class</code> object representing the component
     * type of the new array
     * @param dimensions an array of <code>int</code> types representing the dimensions of
     * the new array
     * @return the new array
     * @exception NullPointerException if the specified 
     * <code>componentType</code> argument is null
     * @exception IllegalArgumentException if the specified <code>dimensions</code> 
     * argument is a zero-dimensional array, or if the number of
     * requested dimensions exceeds the limit on the number of array dimensions 
     * supported by the implementation (typically 255), or if componentType 
     * is Void.TYPE.
     * @exception NegativeArraySizeException if any of the components in
     * the specified <code>dimensions</code> argument is negative.
     */
    public static Object newInstance(Class componentType, int[] dimensions)
	throws IllegalArgumentException, NegativeArraySizeException {
	return multiNewArray(componentType, dimensions);
    }

    /**
     * Returns the length of the specified array object, as an <code>int</code>.
     *
     * @param array the array
     * @return the length of the array
     * @exception IllegalArgumentException if the object argument is not
     * an array
     */
    public static native int getLength(Object array)
	throws IllegalArgumentException;

    /**
     * Returns the value of the indexed component in the specified
     * array object.  The value is automatically wrapped in an object
     * if it has a primitive type.
     *
     * @param array the array
     * @param index the index
     * @return the (possibly wrapped) value of the indexed component in
     * the specified array
     * @exception NullPointerException If the specified object is null
     * @exception IllegalArgumentException If the specified object is not
     * an array
     * @exception ArrayIndexOutOfBoundsException If the specified <code>index</code> 
     * argument is negative, or if it is greater than or equal to the
     * length of the specified array
     */
    public static native Object get(Object array, int index)
 	throws IllegalArgumentException, ArrayIndexOutOfBoundsException;

    /**
     * Returns the value of the indexed component in the specified
     * array object, as a <code>boolean</code>.
     *
     * @param array the array
     * @param index the index
     * @return the value of the indexed component in the specified array
     * @exception NullPointerException If the specified object is null
     * @exception IllegalArgumentException If the specified object is not
     * an array, or if the indexed element cannot be converted to the
     * return type by an identity or widening conversion
     * @exception ArrayIndexOutOfBoundsException If the specified <code>index</code> 
     * argument is negative, or if it is greater than or equal to the
     * length of the specified array
     * @see Array#get
     */
    public static native boolean getBoolean(Object array, int index)
	throws IllegalArgumentException, ArrayIndexOutOfBoundsException;

    /**
     * Returns the value of the indexed component in the specified
     * array object, as a <code>byte</code>.
     *
     * @param array the array
     * @param index the index
     * @return the value of the indexed component in the specified array
     * @exception NullPointerException If the specified object is null
     * @exception IllegalArgumentException If the specified object is not
     * an array, or if the indexed element cannot be converted to the
     * return type by an identity or widening conversion
     * @exception ArrayIndexOutOfBoundsException If the specified <code>index</code> 
     * argument is negative, or if it is greater than or equal to the
     * length of the specified array
     * @see Array#get
     */
    public static native byte getByte(Object array, int index)
	throws IllegalArgumentException, ArrayIndexOutOfBoundsException;

    /**
     * Returns the value of the indexed component in the specified
     * array object, as a <code>char</code>.
     *
     * @param array the array
     * @param index the index
     * @return the value of the indexed component in the specified array
     * @exception NullPointerException If the specified object is null
     * @exception IllegalArgumentException If the specified object is not
     * an array, or if the indexed element cannot be converted to the
     * return type by an identity or widening conversion
     * @exception ArrayIndexOutOfBoundsException If the specified <code>index</code> 
     * argument is negative, or if it is greater than or equal to the
     * length of the specified array
     * @see Array#get
     */
    public static native char getChar(Object array, int index)
	throws IllegalArgumentException, ArrayIndexOutOfBoundsException;

    /**
     * Returns the value of the indexed component in the specified
     * array object, as a <code>short</code>.
     *
     * @param array the array
     * @param index the index
     * @return the value of the indexed component in the specified array
     * @exception NullPointerException If the specified object is null
     * @exception IllegalArgumentException If the specified object is not
     * an array, or if the indexed element cannot be converted to the
     * return type by an identity or widening conversion
     * @exception ArrayIndexOutOfBoundsException If the specified <code>index</code> 
     * argument is negative, or if it is greater than or equal to the
     * length of the specified array
     * @see Array#get
     */
    public static native short getShort(Object array, int index)
	throws IllegalArgumentException, ArrayIndexOutOfBoundsException;

    /**
     * Returns the value of the indexed component in the specified
     * array object, as an <code>int</code>.
     *
     * @param array the array
     * @param index the index
     * @return the value of the indexed component in the specified array
     * @exception NullPointerException If the specified object is null
     * @exception IllegalArgumentException If the specified object is not
     * an array, or if the indexed element cannot be converted to the
     * return type by an identity or widening conversion
     * @exception ArrayIndexOutOfBoundsException If the specified <code>index</code> 
     * argument is negative, or if it is greater than or equal to the
     * length of the specified array
     * @see Array#get
     */
    public static native int getInt(Object array, int index)
	throws IllegalArgumentException, ArrayIndexOutOfBoundsException;

    /**
     * Returns the value of the indexed component in the specified
     * array object, as a <code>long</code>.
     *
     * @param array the array
     * @param index the index
     * @return the value of the indexed component in the specified array
     * @exception NullPointerException If the specified object is null
     * @exception IllegalArgumentException If the specified object is not
     * an array, or if the indexed element cannot be converted to the
     * return type by an identity or widening conversion
     * @exception ArrayIndexOutOfBoundsException If the specified <code>index</code> 
     * argument is negative, or if it is greater than or equal to the
     * length of the specified array
     * @see Array#get
     */
    public static native long getLong(Object array, int index)
	throws IllegalArgumentException, ArrayIndexOutOfBoundsException;