java基础-栈_java中的栈是什么

package cn.itcast.com.istack;

public class Node {

	public Object data;
	
	public Node next;
	
	public  Node(Object data) {
		this(data,null);
	}
	
	public Node() {
		this(null,null);
	}
	
	public Node(Object data,Node next) {
		this.data=data;
		this.next=next;
	}
	
}

package cn.itcast.com.istack;

public interface IStack {

	public void clear();//将栈置空
	
	public boolean isEmpty();//判断为空
	
	public void push(Object x);//压入栈
	
	public Object pop();//移出栈顶
	
	public Object peek();//查看栈顶
	
	public void display();//打印
	
	public int length();//长度
	
}

package cn.itcast.com.istack;
/***
 * 尾插法
 * 
 **/
public class LinkStack implements IStack{

	public Node top;
	
	@Override
	public void clear() {
		top=null;
	}

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

	@Override
	public void push(Object x) {	
		Node p=new Node(x);
		p.next=top;
		top=p;
	}

	@Override
	public Object pop() {
		if(!isEmpty()) {
			Node p=top;
			top=top.next;
			return p.data;
		}else {
			return null;
		}
	}

	@Override
	public Object peek() {
     if(!isEmpty()) {
    	 return top.data;
     }else {
    	 return null;
     }
	}

	@Override
	public void display() {
		Node p=top;
		while(p!=null) {
			System.out.print(p.data.toString()+" ");
			p=p.next;
		}
		System.out.println();
	}

	@Override
	public int length() {
		Node p=top;
		int length=0;
		while(p!=null) {
			length++;
			p=p.next;
		}
		return length;
	}
	
	public static void main(String[] args) {
		System.out.println("栈中各元素为(栈顶到栈底)：");
		LinkStack S=new LinkStack();
		for(int i=1;i<=10;i++) {
			S.push(i);
		}
		S.display();
		if(!S.isEmpty()) {
			System.out.println("栈非空！");
		}
		System.out.println("栈的长度为：" +S.length());
		System.out.println("栈顶元素为："+S.peek());
		System.out.println("去除栈顶元素后，栈中各元素为(栈顶到栈底)：");
		S.pop();
		S.display();
		System.out.println("去除栈中剩余的所有元素！ 进行中。。。");
		S.clear();
		if(S.isEmpty()) {
			System.out.println("栈为空！");
		}
	}
}