学步园

首先实现栈接口IStack,提供出栈、入栈、获取栈顶元素、判断是否为空以及清空栈等基本功能：

定义一个Node类，用于保存链中点的信息：

package my.stack;

public class Node<T> {
	private T data;
	
	private Node<T> next;
	
	public Node(){
		data = null;
		next = null;
	}
	
	public Node(T data){
		this.data = data;
		this.next = null;
	}
	
	public Node(T data, Node<T> next){
		this.data = data;
		this.next = next;
	}
	
	public void setData(T data){
		this.data = data;
	}
	
	public T getData(){
		return this.data;
	}
	
	public void setNext(Node<T> next){
		this.next = next;
	}
	
	public Node<T> getNext(){
		return this.next;
	}
}

然后再实现该IStack接口；

package my.stack;

public class LinkedStack<T> implements IStack<T> {
	private Node<T> top;
	private int size;
	
	public LinkedStack(){
		this.top = null;
		this.size = 0;
	}
	
	public LinkedStack(T data){
		this();
		Node<T> node = new Node<T>(data);
		this.top = node;
		this.size ++;
	}
	
	@Override
	public void clear() {
		this.top = null;
		this.size = 0;
	}

	@Override
	public boolean isEmpty() {
		return this.top == null;
	}

	@Override
	public T peek() {
		return this.top.getData();
	}

	@Override
	public T pop() {
		Node<T> oldTop = this.top;
		if(top == null){
			return null;
		}
		this.top = this.top.getNext();
		this.size --;
		return oldTop.getData();
	}

	@Override
	public void push(T element) {
		Node<T> node = new Node<T>(element,top);
		this.top = node;
		this.size ++;
	}
	
	public int size(){
		return this.size;
	}

}

编写一个基本客户端用来测试功能是否满足，是否有明显的错误;

package my.stack;

public class MyArrayStackClient {
	public static void main(String[] args) {
		ArrayStack<Integer> stack = new ArrayStack<Integer>();
		stack.push(1);
		stack.push(2);
		stack.push(3);
		stack.push(4);
		stack.push(5);
		System.out.println(stack.isEmpty());
		System.out.println(stack.peek());
//		System.out.println(stack.pop());
		System.out.println(stack.size());
		stack.clear();
		System.out.println(stack.size());
	}

}