栈(java实现)

Node

package com.qyc.Stack;

public class Node<E> {
    Node<E> next = null;
    E date;
    public Node(E date) {
        super();
        this.date = date;
    }

}

Stack

package com.qyc.Stack;

public class MyStack<E> {
    // top
    Node<E> top = null;

    // 判空
    public boolean isEmpty() {
        return top == null;
    }

    // 进栈
    public void push(E data) {
        Node<E> newNode = new Node<E>(data);
        newNode.next = top;
        top = newNode;
    }

    // 出栈
    public E pop() {
        if (isEmpty()) {
            return null;
        }
        E data = top.date;
        top = top.next;
        return data;
    }

    // 显示栈顶data
    public E peek() {
        if (isEmpty()) {
            return null;
        }
        return top.date;
    }

}

测试

package com.qyc.Stack;

public class TestStack {
    public static void main(String[] args) {
        MyStack<Integer> myStack = new MyStack<>();
        myStack.push(1);
        myStack.push(2);
        myStack.push(3);
        myStack.push(4);
        System.out.println("栈顶" + myStack.peek());
        System.out.println();
        System.out.println(myStack.pop());
        System.out.println(myStack.pop());
        System.out.println(myStack.pop());
        System.out.println(myStack.pop());
    }
}

栈顶4

4
3
2
1