stackqueue.java

提供了常用的JAVA技术的示例

// P122  例 5-24 用接口实现常用数据结构：队列 栈

package StackQueue;

import javax.swing.UIManager;
import java.awt.*;

class LinkedList{ // 定义 双向链表类
    char data;
    LinkedList back;
    LinkedList forward;
}

interface Access{  // 存取操作的 接口
    void put(char c);
    char get();
}

class Queue implements Access{
    private LinkedList QHead=new LinkedList();
    private LinkedList QRear=QHead;
    public void put(char c){ // 存 数
        QRear.forward=new LinkedList();
        QRear.forward.data=c;
        QRear.forward.back=QRear;
        QRear=QRear.forward;
    }
    public char get(){ // 取 数
        if(QHead!=QRear){
            QHead.forward.back=null;
            QHead=QHead.forward;
            return QHead.data;
            }
        else{
            System.out.println("this queue is empty !");
            return '\0';
            }
    }
}

class Stack implements Access{
    private LinkedList bottom=new LinkedList();
    private LinkedList top=bottom;
    public void put(char c){
        top.forward=new LinkedList();
        top.forward.data=c;
        top.forward.back=top;
        top=top.forward;
    }
    public char get(){
        if (top!=bottom){
            char ch=top.data;
            top.back.forward=null;
            top=top.back;
            return ch;
        }
        else{
            System.out.println("this stack is empty !");
            return '\0';
        }
    }
}
public class StackQueue {
    public static void main(String[] args) {
        char ch;
        // 可以把接口看成一种数据类型，不需要了解对象所对应的具体的类。
        Access qu=new Queue();
        Access st=new Stack();
        //Queue  qu=new Queue();
        //Stack  st=new Stack();
        qu.put('1');
        qu.put('2');
        System.out.println("queue: ");
        if((ch=qu.get())!='\0')
            System.out.println(ch);
        if((ch=qu.get())!='\0')
            System.out.println(ch);
        if((ch=qu.get())!='\0')
            System.out.println(ch);

        System.out.println("stack: ");
        st.put('1');
        st.put('2');
        if((ch=st.get())!='\0')
            System.out.println(ch);
        if((ch=st.get())!='\0')
            System.out.println(ch);
        if((ch=st.get())!='\0')
            System.out.println(ch);

  }
}