Array.java

/*
 * Copyright (c) 1996, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package java.lang.reflect;

import jdk.internal.HotSpotIntrinsicCandidate;

/**
 * The {@code Array} class provides static methods to dynamically create and
 * access Java arrays.
 *
 * <p>{@code Array} permits widening conversions to occur during a get or set
 * operation, but throws an {@code IllegalArgumentException} if a narrowing
 * conversion would occur.
 *
 * @author Nakul Saraiya
 * @since 1.1
 */
// 数组
public final class Array {
    
    /*▼ 构造方法 ████████████████████████████████████████████████████████████████████████████████┓ */
    
    /**
     * Constructor.  Class Array is not instantiable.
     */
    private Array() {
    }
    
    /*▲ 构造方法 ████████████████████████████████████████████████████████████████████████████████┛ */
    
    
    
    /*▼ 创建数组实例 ████████████████████████████████████████████████████████████████████████████████┓ */
    
    /**
     * 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>
     *
     * <p>The number of dimensions of the new array must not
     * exceed 255.
     *
     * @param componentType the {@code Class} object representing the
     *                      component type of the new array
     * @param length        the length of the new array
     *
     * @return the new array
     *
     * @throws NullPointerException       if the specified
     *                                    {@code componentType} parameter is null
     * @throws IllegalArgumentException   if componentType is {@link
     *                                    Void#TYPE} or if the number of dimensions of the requested array
     *                                    instance exceed 255.
     * @throws NegativeArraySizeException if the specified {@code length}
     *                                    is negative
     */
    // 创建一维数组实例
    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}
     * represents a non-array class or interface, the new array
     * has {@code dimensions.length} dimensions and
     * {@code componentType} as its component type. If
     * {@code componentType} represents an array class, the
     * number of dimensions of the new array is equal to the sum
     * of {@code dimensions.length} and the number of
     * dimensions of {@code componentType}. In this case, the
     * component type of the new array is the component type of
     * {@code componentType}.
     *
     * <p>The number of dimensions of the new array must not
     * exceed 255.
     *
     * @param componentType the {@code Class} object representing the component
     *                      type of the new array
     * @param dimensions    an array of {@code int} representing the dimensions of
     *                      the new array
     *
     * @return the new array
     *
     * @throws NullPointerException       if the specified
     *                                    {@code componentType} argument is null
     * @throws IllegalArgumentException   if the specified {@code dimensions}
     *                                    argument is a zero-dimensional array, if componentType is {@link
     *                                    Void#TYPE}, or if the number of dimensions of the requested array
     *                                    instance exceed 255.
     * @throws NegativeArraySizeException if any of the components in
     *                                    the specified {@code dimensions} argument is negative.
     */
    // 创建多维数组实例
    public static Object newInstance(Class<?> componentType, int... dimensions) throws IllegalArgumentException, NegativeArraySizeException {
        return multiNewArray(componentType, dimensions);
    }
    
    /*▲ 创建数组实例 ████████████████████████████████████████████████████████████████████████████████┛ */
    
    
    
    /*▼ 设置值 ████████████████████████████████████████████████████████████████████████████████┓ */
    
    /**
     * Sets the value of the indexed component of the specified array
     * object to the specified {@code byte} value.
     *
     * @param array the array
     * @param index the index into the array
     * @param b     the new value of the indexed component
     *
     * @throws NullPointerException           If the specified object argument
     *                                        is null
     * @throws IllegalArgumentException       If the specified object argument
     *                                        is not an array, or if the specified value cannot be converted
     *                                        to the underlying array's component type by an identity or a
     *                                        primitive widening conversion
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to
     *                                        the length of the specified array
     * @see Array#set
     */
    public static native void setByte(Object array, int index, byte b) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Sets the value of the indexed component of the specified array
     * object to the specified {@code short} value.
     *
     * @param array the array
     * @param index the index into the array
     * @param s     the new value of the indexed component
     *
     * @throws NullPointerException           If the specified object argument
     *                                        is null
     * @throws IllegalArgumentException       If the specified object argument
     *                                        is not an array, or if the specified value cannot be converted
     *                                        to the underlying array's component type by an identity or a
     *                                        primitive widening conversion
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to
     *                                        the length of the specified array
     * @see Array#set
     */
    public static native void setShort(Object array, int index, short s) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Sets the value of the indexed component of the specified array
     * object to the specified {@code int} value.
     *
     * @param array the array
     * @param index the index into the array
     * @param i     the new value of the indexed component
     *
     * @throws NullPointerException           If the specified object argument
     *                                        is null
     * @throws IllegalArgumentException       If the specified object argument
     *                                        is not an array, or if the specified value cannot be converted
     *                                        to the underlying array's component type by an identity or a
     *                                        primitive widening conversion
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to
     *                                        the length of the specified array
     * @see Array#set
     */
    public static native void setInt(Object array, int index, int i) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Sets the value of the indexed component of the specified array
     * object to the specified {@code long} value.
     *
     * @param array the array
     * @param index the index into the array
     * @param l     the new value of the indexed component
     *
     * @throws NullPointerException           If the specified object argument
     *                                        is null
     * @throws IllegalArgumentException       If the specified object argument
     *                                        is not an array, or if the specified value cannot be converted
     *                                        to the underlying array's component type by an identity or a
     *                                        primitive widening conversion
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to
     *                                        the length of the specified array
     * @see Array#set
     */
    public static native void setLong(Object array, int index, long l) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Sets the value of the indexed component of the specified array
     * object to the specified {@code float} value.
     *
     * @param array the array
     * @param index the index into the array
     * @param f     the new value of the indexed component
     *
     * @throws NullPointerException           If the specified object argument
     *                                        is null
     * @throws IllegalArgumentException       If the specified object argument
     *                                        is not an array, or if the specified value cannot be converted
     *                                        to the underlying array's component type by an identity or a
     *                                        primitive widening conversion
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to
     *                                        the length of the specified array
     * @see Array#set
     */
    public static native void setFloat(Object array, int index, float f) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Sets the value of the indexed component of the specified array
     * object to the specified {@code double} value.
     *
     * @param array the array
     * @param index the index into the array
     * @param d     the new value of the indexed component
     *
     * @throws NullPointerException           If the specified object argument
     *                                        is null
     * @throws IllegalArgumentException       If the specified object argument
     *                                        is not an array, or if the specified value cannot be converted
     *                                        to the underlying array's component type by an identity or a
     *                                        primitive widening conversion
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to
     *                                        the length of the specified array
     * @see Array#set
     */
    public static native void setDouble(Object array, int index, double d) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Sets the value of the indexed component of the specified array
     * object to the specified {@code char} value.
     *
     * @param array the array
     * @param index the index into the array
     * @param c     the new value of the indexed component
     *
     * @throws NullPointerException           If the specified object argument
     *                                        is null
     * @throws IllegalArgumentException       If the specified object argument
     *                                        is not an array, or if the specified value cannot be converted
     *                                        to the underlying array's component type by an identity or a
     *                                        primitive widening conversion
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to
     *                                        the length of the specified array
     * @see Array#set
     */
    public static native void setChar(Object array, int index, char c) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Sets the value of the indexed component of the specified array
     * object to the specified {@code boolean} value.
     *
     * @param array the array
     * @param index the index into the array
     * @param z     the new value of the indexed component
     *
     * @throws NullPointerException           If the specified object argument
     *                                        is null
     * @throws IllegalArgumentException       If the specified object argument
     *                                        is not an array, or if the specified value cannot be converted
     *                                        to the underlying array's component type by an identity or a
     *                                        primitive widening conversion
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to
     *                                        the length of the specified array
     * @see Array#set
     */
    public static native void setBoolean(Object array, int index, boolean z) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Sets the value of the indexed component of the specified array
     * object to the specified new value.  The new value is first
     * automatically unwrapped if the array has a primitive component
     * type.
     *
     * @param array the array
     * @param index the index into the array
     * @param value the new value of the indexed component
     *
     * @throws NullPointerException           If the specified object argument
     *                                        is null
     * @throws IllegalArgumentException       If the specified object argument
     *                                        is not an array, or if the array component type is primitive and
     *                                        an unwrapping conversion fails
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to
     *                                        the length of the specified array
     */
    public static native void set(Object array, int index, Object value) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /*▲ 设置值 ████████████████████████████████████████████████████████████████████████████████┛ */
    
    
    
    /*▼ 获取值 ████████████████████████████████████████████████████████████████████████████████┓ */
    
    /**
     * Returns the value of the indexed component in the specified
     * array object, as a {@code byte}.
     *
     * @param array the array
     * @param index the index
     *
     * @return the value of the indexed component in the specified array
     *
     * @throws NullPointerException           If the specified object is null
     * @throws 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
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        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 short}.
     *
     * @param array the array
     * @param index the index
     *
     * @return the value of the indexed component in the specified array
     *
     * @throws NullPointerException           If the specified object is null
     * @throws 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
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        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}.
     *
     * @param array the array
     * @param index the index
     *
     * @return the value of the indexed component in the specified array
     *
     * @throws NullPointerException           If the specified object is null
     * @throws 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
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        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}.
     *
     * @param array the array
     * @param index the index
     *
     * @return the value of the indexed component in the specified array
     *
     * @throws NullPointerException           If the specified object is null
     * @throws 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
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        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;
    
    /**
     * Returns the value of the indexed component in the specified
     * array object, as a {@code float}.
     *
     * @param array the array
     * @param index the index
     *
     * @return the value of the indexed component in the specified array
     *
     * @throws NullPointerException           If the specified object is null
     * @throws 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
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to the
     *                                        length of the specified array
     * @see Array#get
     */
    public static native float getFloat(Object array, int index) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Returns the value of the indexed component in the specified
     * array object, as a {@code double}.
     *
     * @param array the array
     * @param index the index
     *
     * @return the value of the indexed component in the specified array
     *
     * @throws NullPointerException           If the specified object is null
     * @throws 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
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        argument is negative, or if it is greater than or equal to the
     *                                        length of the specified array
     * @see Array#get
     */
    public static native double getDouble(Object array, int index) throws IllegalArgumentException, ArrayIndexOutOfBoundsException;
    
    /**
     * Returns the value of the indexed component in the specified
     * array object, as a {@code char}.
     *
     * @param array the array
     * @param index the index
     *
     * @return the value of the indexed component in the specified array
     *
     * @throws NullPointerException           If the specified object is null
     * @throws 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
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        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 boolean}.
     *
     * @param array the array
     * @param index the index
     *
     * @return the value of the indexed component in the specified array
     *
     * @throws NullPointerException           If the specified object is null
     * @throws 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
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        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.  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
     *
     * @throws NullPointerException           If the specified object is null
     * @throws IllegalArgumentException       If the specified object is not
     *                                        an array
     * @throws ArrayIndexOutOfBoundsException If the specified {@code index}
     *                                        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;
    
    /*▲ 获取值 ████████████████████████████████████████████████████████████████████████████████┛ */
    
    
    
    /**
     * Returns the length of the specified array object, as an {@code int}.
     *
     * @param array the array
     *
     * @return the length of the array
     *
     * @throws IllegalArgumentException if the object argument is not
     *                                  an array
     */
    // 获取数组长度
    @HotSpotIntrinsicCandidate
    public static native int getLength(Object array) throws IllegalArgumentException;
    
    
    
    @HotSpotIntrinsicCandidate
    private static native Object newArray(Class<?> componentType, int length) throws NegativeArraySizeException;
    
    private static native Object multiNewArray(Class<?> componentType, int[] dimensions) throws IllegalArgumentException, NegativeArraySizeException;
    
}