/**

     * The maximum size of array to allocate. --申请新数组最大长度

     * Some VMs reserve some header words in an array.

     * Attempts to allocate larger arrays may result in

     * OutOfMemoryError: Requested array size exceeds VM limit  --如果申请的数组占用的内心大于JVM的限制抛出异常

     */

    private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;//为什么减去8看注释第2行

    /**

     * Increases the capacity to ensure that it can hold at least the

     * number of elements specified by the minimum capacity argument.

     *

     * @param minCapacity the desired minimum capacity

     */

    private void grow(int minCapacity) {

        // overflow-conscious code

        int oldCapacity = elementData.length;

        int newCapacity = oldCapacity + (oldCapacity >> 1); //新申请的长度为old的3/2倍同时使用位移运算更高效，JDK5中： (oldCapacity *3)/2+1

        if (newCapacity - minCapacity < 0)  

            newCapacity = minCapacity; 

        if (newCapacity - MAX_ARRAY_SIZE > 0) //你懂的

            newCapacity = hugeCapacity(minCapacity);

        // minCapacity is usually close to size, so this is a win:

        elementData = Arrays.copyOf(elementData, newCapacity);

    }

 //可以申请的最大长度

    private static int hugeCapacity(int minCapacity) { 

        if (minCapacity < 0) // overflow

            throw new OutOfMemoryError();

        return (minCapacity > MAX_ARRAY_SIZE) ?

            Integer.MAX_VALUE :

            MAX_ARRAY_SIZE;

    }