链式栈——Java实现

  1 package struct;
  2
  3 //接口
  4 interface ILinkStack{
  5     //栈中元素个数（栈大小）
  6     int size();
  7     //取栈顶元素
  8     Object top();
  9     //判断栈是否为空
 10     boolean isEmpty();
 11     //入栈
 12     Object pop();
 13     //出栈
 14     Object push(Object value);
 15     //清空栈
 16     void clear();
 17 }
 18
 19 //工厂类
 20 class Factory2{
 21     private Factory2(){}
 22     public static ILinkStack getILinkStackInstance(){
 23         return new LinkStackImpl();
 24     }
 25 }
 26
 27 class LinkStackImpl implements ILinkStack {
 28     //栈顶元素
 29     Node top;
 30     //链表长度记录入栈元素
 31     private int count;
 32     class Node{
 33         Node prev;
 34         Node next;
 35         Object data;
 36         public Node(Object data) {
 37             this.data = data;
 38         }
 39     }
 40
 41     public int size() {
 42         return count;
 43     }
 44
 45     public Object top() {
 46         return top.data;
 47     }
 48     //判栈空
 49     public boolean isEmpty() {
 50         return (size()==0);
 51     }
 52     //入栈
 53     public Object push(Object value) {
 54         Node node = new Node(value);
 55         if(top == null){
 56             top = node;
 57         }else{
 58             top.next = node;
 59             node.prev = top;
 60             top = top.next;
 61         }
 62         count++;
 63         return top;
 64     }
 65     public void print(){
 66         System.out.println("从栈顶到栈底打印栈中元素：");
 67         myPrint(top);
 68         return;
 69     }
 70     //栈顶->栈底打印链表
 71     private void myPrint(Node top){
 72         for(Node node = top;node!=null;node=node.prev){
 73             System.out.print(node.data+" ");
 74         }
 75     }
 76     //出栈
 77     public Object pop() {
 78         Node node = top;
 79         if(top == null){
 80             System.out.println("空栈无要出栈元素");
 81             return -1;
 82         }else{
 83             top = top.prev;
 84             node.prev = null;
 85             node.data = null;
 86         }
 87         count--;
 88         return top();
 89     }
 90     //清空栈
 91     public void clear(){
 92         Node node1 = top;
 93         for(Node node = top;node!=null;){
 94             node = node.prev;
 95             node1.data = null;
 96             node1.prev = null;
 97             count--;
 98         }
 99     }
100 }
101 public class LinkStack {
102     public static void main(String[] args) {
103         ILinkStack linkStack = Factory2.getILinkStackInstance();
104         //向下转型
105         LinkStackImpl linkStack1 = (LinkStackImpl)linkStack;
106         System.out.println("============测试isEmpty函数(空栈)=================");
107         System.out.println(linkStack.isEmpty());
108         System.out.println("============测试push和print函数=================");
109         linkStack.push(5);
110         linkStack.push(9);
111         linkStack.push(10);
112         linkStack.push(1);
113         linkStack.push(8);
114         linkStack.push(12);
115         linkStack.push(6);
116         linkStack.push(3);
117         linkStack1.print();
118         System.out.println();
119         System.out.println("============入栈后测试top函数=================");
120         System.out.println(linkStack.top());
121         System.out.println("============入栈后测试size函数=================");
122         System.out.println(linkStack.size());
123         System.out.println("============测试pop和print函数=================");
124         linkStack.pop();
125         linkStack.pop();
126         linkStack.pop();
127         linkStack1.print();
128         System.out.println();
129         System.out.println("============出站后测试top函数=================");
130         System.out.println(linkStack.top());
131         System.out.println("============出栈后测试size函数=================");
132         System.out.println(linkStack.size());
133         System.out.println("============测试clear后size函数=================");
134         linkStack.clear();
135         System.out.println(linkStack.size());
136     }
137 }