GUI 数字を次々と入力できる電卓風のアプリ

以下は数字を次々と入力できるSwingで作った電卓風のGUIアプリです。計算はできません。計算できるのはこっち。

コードを改造して何か別のものに使う際にどうぞ。


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

class Sample1 extends JFrame{
private static final long serialVersionUID = 1L;

JPanel contentPane = new JPanel();
BorderLayout borderLayout1 = new BorderLayout();
JTextField result = new JTextField("");


 public static void main(String args[]){
Sample1 frame = new Sample1("Practice window.");
frame.setVisible(true);
 }

 Sample1(String title){
        contentPane.setLayout(borderLayout1);
setContentPane(contentPane);
setTitle(title);
setSize(new Dimension(250, 300));
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

contentPane.add(result, BorderLayout.NORTH);

JPanel keyPanel = new JPanel();
keyPanel.setLayout(new GridLayout(4, 3));
contentPane.add(keyPanel, BorderLayout.CENTER);

keyPanel.add(new NumberButton("7"), 0);
keyPanel.add(new NumberButton("8"), 1);
keyPanel.add(new NumberButton("9"), 2);
keyPanel.add(new NumberButton("4"), 3);
keyPanel.add(new NumberButton("5"), 4);
keyPanel.add(new NumberButton("6"), 5);
keyPanel.add(new NumberButton("1"), 6);
keyPanel.add(new NumberButton("2"), 7);
keyPanel.add(new NumberButton("3"), 8);
keyPanel.add(new NumberButton("0"), 9);
keyPanel.add(new JButton("Calc"), 10);

contentPane.add(new JButton("C"), BorderLayout.SOUTH);
setVisible(true);
   }

    public void appendResult(String c) {
result.setText(result.getText() + c);
   }

public class NumberButton extends JButton implements ActionListener {
private static final long serialVersionUID = 1L;

public NumberButton(String keyTop) {
super(keyTop);
this.addActionListener(this);
}

public void actionPerformed(ActionEvent evt) {
String keyNumber = this.getText();
appendResult(keyNumber);
}
}
}