整数版计算器

package aa;

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

public class Calculator1 extends JFrame implements ActionListener {

 private JTextField m_textField = new JTextField(12);
 private JButton[] m_button = { new JButton("1"), new JButton("2"),
   new JButton("3"), new JButton("4"), new JButton("5"),
   new JButton("6"), new JButton("7"), new JButton("8"),
   new JButton("9"), new JButton("0"), new JButton("+"),
   new JButton("-"), new JButton("*"), new JButton("/"),
   new JButton("."), new JButton("="), new JButton("C") };

 public Calculator1() {
  super("Calculator");
  Container container = getContentPane();
  container.setLayout(new FlowLayout(FlowLayout.CENTER));
  container.add(m_textField);
  for (int i = 0; i <= 16; i++) {
   container.add(m_button[i]);
   m_button[i].addActionListener(this);
  }
  setSize(200, 200);
  setVisible(true);
 }

 int flag;
 double value1, value2, result;//

 public void actionPerformed(ActionEvent e) {

  int i;
  for (i = 0; i < 10; i++) {
   if (e.getSource() == m_button[i]) {
    String value = String.valueOf((i + 1) % 10);
    m_textField.setText(m_textField.getText() + value);
   }
  }

  if (e.getSource() == m_button[10]) //
  {
   flag = 1;
   value1 = Double.parseDouble(m_textField.getText());//
   m_textField.setText(""); //

  } else if (e.getSource() == m_button[11]) //
  {
   flag = 2;
   value1 = Double.parseDouble(m_textField.getText());
   m_textField.setText("");

  } else if (e.getSource() == m_button[12])//
  {
   flag = 3;
   value1 = Double.parseDouble(m_textField.getText());
   m_textField.setText("");

  } else if (e.getSource() == m_button[13]) //
  {
   flag = 4;
   value1 = Double.parseDouble(m_textField.getText());
   m_textField.setText("");

  } else if (e.getSource() == m_button[15]) // =
  {
   value2 = Double.parseDouble(m_textField.getText()); //
   if (flag == 1)
    result = value1 + value2;
   else if (flag == 2)
    result = value1 - value2;
   else if (flag == 3)
    result = value1 * value2;
   else if (flag == 4) {
    if (value2 != 0)
     result = value1 / value2;
    else
     result = 0;
   }
   String r = String.valueOf(result);
   m_textField.setText(r);
  } else if (e.getSource() == m_button[14]) // .
  {
   boolean b = true;// whether exists '.'
   String r = m_textField.getText();//
   for (int j = 0; j < r.length(); j++) {
    if (r.charAt(j) == ".".charAt(0)){
     b = false;
    }
   }
   if (b){
    m_textField.setText(m_textField.getText() + ".");
   }
  } else if (e.getSource() == m_button[16]) //
   m_textField.setText("");

 }

 public static void main(String args[]) {
  Calculator1 app = new Calculator1();
  app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
 }

}