/**
* The maximum size of array to allocate. --申請新數(shù)組最大長度
* Some VMs reserve some header words in an array.
* Attempts to allocate larger arrays may result in
* OutOfMemoryError: Requested array size exceeds VM limit --如果申請的數(shù)組占用的內(nèi)心大于JVM的限制拋出異常
*/
private static final int MAX_ARRAY_SIZE = Integer.MAX_VALUE - 8;//為什么減去8看注釋第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); //新申請的長度為old的3/2倍同時使用位移運算更高效，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);
}
//可以申請的最大長度
private static int hugeCapacity(int minCapacity) {
if (minCapacity < 0) // overflow
throw new OutOfMemoryError();
return (minCapacity > MAX_ARRAY_SIZE) ?
Integer.MAX_VALUE :
MAX_ARRAY_SIZE;
}