handleback.java

《Java课程设计》第二版

import java.util.LinkedList;
import javax.swing.*;
import java.awt.event.*;
public class HandleBack implements ActionListener{
    LinkedList<String> list;
    JTextField resultShow,showComputerProcess;          
    HandleBack(LinkedList<String> list,JTextField t1,JTextField t2){
        this.list=list;
        resultShow=t1;
        showComputerProcess=t2; 
    }
    public void actionPerformed(ActionEvent e){
        if(list.size()==1){                               
           String num=(String)list.getFirst();
           if(num.length()>=1){
                 num=num.substring(0,num.length()-1);
                 list.set(0,num);                  
                 resultShow.setText(num);
                 showComputerProcess.setText(""+num);
           }
           else{
                 list.removeLast();                  
                 resultShow.setText("0");
                 showComputerProcess.setText("0");
           }
        }
        else if(list.size()==3){
           String num=(String)list.getLast();
           if(num.length()>=1){
                 num=num.substring(0,num.length()-1);
                 list.set(2,num);                  
                 resultShow.setText(num);
                 showComputerProcess.setText(num);
           }
           else{
                 list.removeLast();                  
                 resultShow.setText("0");
                 showComputerProcess.setText("0");
           }
       }
    }
}