数据结构--链栈  java 实现

1.链栈，top指向栈顶元素。顺序栈，和 IStack 接口在这点击打开链接

//节点的定义  class Node{      public Object data;      public Node next;      //无参构造方法      public Node(){          this(null,null);      }      //一个参数的构造方法      public Node(Object data){          this(data,null);      }      //两个参数的构造方法      public Node(Object data, Node next){          this.data = data;          this.next = next;      }  }  //链栈类public class LinkStack implements IStack{private Node top;//指向栈顶元素，空栈时为null//置空栈@Overridepublic void clear() {// TODO Auto-generated method stubtop = null;}//判断栈是否为空@Overridepublic boolean isEmpty() {// TODO Auto-generated method stubreturn top == null;}//查询栈顶元素@Overridepublic Object peek() {// TODO Auto-generated method stubif(!isEmpty())return top.data;return null;}//链栈的长度@Overridepublic int length() {// TODO Auto-generated method stubNode p = top;int length = 0;while(p != null){length++;p = p.next;}return length;}//元素入栈@Overridepublic void push(Object x) {// TODO Auto-generated method stubNode p = new Node(x);p.next = top;top = p;}//栈顶元素出栈@Overridepublic Object pop() {// TODO Auto-generated method stubif(isEmpty()){return null;}Node p = top;top = top.next;return p.data;}/* * 测试用，忽略 *///public static void main(String[] args) throws Exception{//LinkStack mystack = new LinkStack();//mystack.push(1);//mystack.push(2);//mystack.push(3);//mystack.push(4);//mystack.push(5);//System.out.println(mystack.length());//System.out.println(mystack.isEmpty());//System.out.println(mystack.peek());//for(int i=0;i<5;i++){//System.out.println(mystack.pop());//}//System.out.println(mystack.isEmpty());//System.out.println(mystack.length());//}}