Java数据结构之栈

public class MyStack {
    private int[] elements;

    public MyStack()
    {
        elements = new int[0];
    }

    //压入元素
    public void push(int element)
    {
        int[] newArr = new int[elements.length+1];
        for(int i = 0;i < elements.length;i++)
        {
            newArr[i] = elements[i];
        }
        newArr[elements.length] = element;
        elements = newArr;
    }

    //取出栈顶元素
    public int pop()
    {
        if(elements.length == 0)
        {
            throw new RuntimeException("stack is empty");
        }
        int element = elements[elements.length-1];
        int[] newArr = new int[elements.length-1];
        //取出除了最后一个元素的其余元素
        for(int i = 0;i < elements.length-1;i++)
        {
            newArr[i] = elements[i];
        }
        elements = newArr;

        return element;
    }

    //查看栈顶元素
    public int peek()
    {
        if(elements.length == 0)
        {
            throw new RuntimeException("stack is empty");
        }

        return elements[elements.length-1];
    }

    //判断栈是否为空
    public boolean isEmpty()
    {
        return elements.length == 0;
    }
}