handledigit.java

书上的例子

import java.util.LinkedList;
import javax.swing.*;
import java.awt.event.*;

public class HandleDigit implements ActionListener {
    LinkedList<String> list;
    JTextField resultShow;
    JTextField showComputerProcess;

    HandleDigit(LinkedList<String> list, JTextField t1, JTextField t2) {
        this.list = list;
        resultShow = t1;
        showComputerProcess = t2;
    }

    public void actionPerformed(ActionEvent e) {
        NumberButton b = (NumberButton)e.getSource();
        if (list.size() == 0) {
            int number = b.getNumber();
            list.add("" + number);
            resultShow.setText("" + number);
            showComputerProcess.setText("" + list.get(0));
        } else if (list.size() == 1) {
            int number = b.getNumber();
            String num = list.getFirst();
            String s = num.concat("" + number);
            list.set(0, s);
            resultShow.setText(s);
            showComputerProcess.setText("" + list.get(0));
        } else if (list.size() == 2) {
            int number = b.getNumber();
            list.add("" + number);
            resultShow.setText("" + number);
            showComputerProcess.setText("" + list.get(0) + " " + list.get(1) + " " + list.get(2));
        } else if (list.size() == 3) {
            int number = b.getNumber();
            String num = list.getLast();
            String s = num.concat("" + number);
            list.set(2, s);
            resultShow.setText(s);
            showComputerProcess.setText("" + list.get(0) + " " + list.get(1) + " " + list.get(2));
        }
    }
}