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()
   {  setLayout(new FlowLayout());
      add(addButton);
      add(subButton);
      add(input);
      add(resetButton);
      add(output);
      addButton.addActionListener(this);
      subButton.addActionListener(this);
      resetButton.addActionListener(this);
      handleReset();
   }
   private 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();
   }
}