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 }