消除过期对象引用 堆栈隐患

https://www.cnblogs.com/13jhzeng/p/5615301.html

public class Stack {
    pprivate Object[] elements;
    private int size = 0;
    private static final int DEFAULT_INITAL_CAPACITY = 16;
    
    public Stack() {
        elements = new Object[DEFAULT_INITAL_CAPACITY];
    }
    
    public void push(Object e) {
        ensureCapacity();
        elements[size++] = e;
    }
    
    public Object pop() {
        if(size == 0) {
            throw new EmptyStackException();
        }
        return elements[--size];
    }
    
    private void ensureCapacity() {
        if(elements.length == size)
            elements = Arrays.copyOf(elements, 2 * size + 1);
    }
}

当数据急速增加时候，又突然变小时候，数据访问是通过size 来访问的，当数据便小的时候，数据原本不会丢失，

直到程序结束时候才会释放掉，

可以这样做

    public Object pop() {
        if(size == 0) {
            throw new EmptyStackException();
        }

        Object obj = element[--size];

        element[size] = null;

        return obj;
    }