addingmachine.java

Java程序设计技巧与开发实例附书源代码。

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class AddingMachine
    extends Applet
    implements ActionListener
{
   private Button addButton = new Button("Add");
   private Button subButton = new Button("Subtract");
   private Button resetButton = new Button("Reset");
   private TextField input = new TextField(10);
   private TextField output = new TextField(10);
   private double total = 0;
   public void init()
   {
      Panel buttons = new Panel();
      buttons.setLayout(new FlowLayout());
      buttons.add(addButton);
      buttons.add(subButton);
      buttons.add(resetButton);
      Panel display = new Panel();
      display.setLayout(new GridLayout(2, 2));
      display.add(new Label("Add/subtract:"));
      display.add(input);
      display.add(new Label("Result:"));
      display.add(output);
      setLayout(new BorderLayout());
      add("Center", display);
      add("South", buttons);
      addButton.addActionListener(this);
      subButton.addActionListener(this);
      resetButton.addActionListener(this);
      handleReset();
   }

   // handleAdd, handleSubtract, handleResetº̡ctionPerformed·½·¨
   // ûԐ¸ı⋊
   public void handleAdd()
   {
      total += Double.valueOf(input.getText().trim()).doubleValue();
      output.setText(String.valueOf(total));
   }

   private void handleSubtract()
   {
      total -= Double.valueOf(input.getText().trim()).doubleValue();
      output.setText(String.valueOf(total));
   }

   private void handleReset()
   {
      total = 0.0;
      input.setText("0.0");
      output.setText("0.0");
   }

   public void actionPerformed(ActionEvent e)
   {
      if (e.getSource() == addButton)
      {
         handleAdd();
      }
      else if (e.getSource() == subButton)
      {
         handleSubtract();
      }
      else if (e.getSource() == resetButton)
      {
         handleReset();
      }
   }

}