javaで書いた電子計算機

javaで書いた計算機です。プログラミングの参考にどうぞ。
GUIのプログラムです。Swingを使用したものなのでSwing Designerを使えば簡単に同じような計算機ができます。


import javax.swing.*;
import java.awt.event.*;
import java.awt.Container;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.GridLayout;

class CalcSample extends JFrame{
private static final long serialVersionUID = 1L;
BorderLayout borderLayout1 = new BorderLayout();
JPanel contentPane = new JPanel();
JTextField result = new JTextField("");
double stackedValue = 0.0;
boolean isStacked = false;
boolean afterCalc = false;
String currentOp = "";

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

  CalcSample(String title){
contentPane.setLayout(borderLayout1);
setTitle(title);
setSize(250, 350);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setContentPane(contentPane);

contentPane.add(result, BorderLayout.NORTH);

JPanel keyPanel = new JPanel();
keyPanel.setLayout(new GridLayout(4, 4));
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 CalcButton("÷"), 3);
keyPanel.add(new NumberButton("4"), 4);
keyPanel.add(new NumberButton("5"), 5);
keyPanel.add(new NumberButton("6"), 6);
keyPanel.add(new CalcButton("×"), 7);
keyPanel.add(new NumberButton("1"), 8);
keyPanel.add(new NumberButton("2"), 9);
keyPanel.add(new NumberButton("3"), 10);
keyPanel.add(new CalcButton("-"), 11);
keyPanel.add(new NumberButton("0"), 12);
keyPanel.add(new CalcButton("."), 13);
keyPanel.add(new CalcButton("+"), 14);
keyPanel.add(new CalcButton("="), 15);

contentPane.add(new ClearButton(), BorderLayout.SOUTH);
  }


public void appendResult(String c) {
if (!afterCalc)
result.setText(result.getText() + c);
else {
result.setText(c);
afterCalc = false;
}
}


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);
}
}


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

public CalcButton(String op) {
super(op);
this.addActionListener(this);
}

public void actionPerformed(ActionEvent e) {
if (isStacked) {
double resultValue = (Double.valueOf(result.getText()))
.doubleValue();
if (currentOp.equals("+"))
stackedValue += resultValue;
else if (currentOp.equals("-"))
stackedValue -= resultValue;
else if (currentOp.equals("×"))
stackedValue *= resultValue;
else if (currentOp.equals("÷"))
stackedValue /= resultValue;
result.setText(String.valueOf(stackedValue));
}
currentOp = this.getText();
stackedValue = (Double.valueOf(result.getText())).doubleValue();
afterCalc = true;
if (currentOp.equals("="))
isStacked = false;
else
isStacked = true;
}
}


public class ClearButton extends JButton implements ActionListener {

private static final long serialVersionUID = 1L;

public ClearButton() {
super("C");
this.addActionListener(this);
}

public void actionPerformed(ActionEvent evt) {
stackedValue = 0.0;
afterCalc = false;
isStacked = false;
result.setText("");
}
}
}