textguitwo.java

《A first book of java》by Gary J.Bronson 北大出版社

import javax.swing.*;
import java.awt.event.*;
import java.awt.Container;  // need this to add controls
import java.awt.*;  // need this for layout manager 
public class TextGuiTwo extends JFrame
{
  private JFrame mainFrame;
  private JButton messageButton;
  private JButton clearButton;
  private JButton exitButton;
  private JTextField tField;
 
  public TextGuiTwo() // a constructor
  {
    mainFrame = new JFrame("The Hello Application - Ver. 3.0");
      // create all components
    messageButton = new JButton("Message");  
    clearButton = new JButton("Clear");
    exitButton = new JButton("Exit");
    tField = new JTextField("Hello World!");
      // get the content pane 
    Container c = mainFrame.getContentPane(); // Step 2 - message statement
    
      // add the components to the ContentPane 
    c.add(tField,BorderLayout.NORTH);
    c.add(messageButton,BorderLayout.WEST);
    c.add(clearButton,BorderLayout.CENTER);
    c.add(exitButton,BorderLayout.EAST);
    
      // create accelerator keys
    messageButton.setMnemonic('M');
    clearButton.setMnemonic('C');
    exitButton.setMnemonic('x');
    mainFrame.setSize(300,150);
       // define and register window event handler
    mainFrame.addWindowListener(new WindowAdapter()
    {
      public void windowClosing(WindowEvent e) {System.exit(0);}
    });
    
      // create and register the button event handlers
    MessageButtonHandler mhandler = new MessageButtonHandler(); // instantiate a handler
    messageButton.addActionListener(mhandler);  // register the handler    
 
    ClearButtonHandler chandler = new ClearButtonHandler();  // instantiate a handler
    clearButton.addActionListener(chandler);  // register the handler    
 
    ExitButtonHandler ehandler = new ExitButtonHandler();  // instantiate a handler
    exitButton.addActionListener(ehandler);  // register the handler    
    mainFrame.show();
  } 
  
     // inner classes for the button event handlers
  class MessageButtonHandler implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      tField.setText("Hello World Once Again!");
    }
  }  // end of inner class
  class ClearButtonHandler implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      tField.setText("");
    }
  }  // end of inner class
  class ExitButtonHandler implements ActionListener
  {
    public void actionPerformed(ActionEvent e)
    {
      System.exit(0);
    }
  }  // end of inner class
  public static void main(String args[])
  {
    new TextGuiTwo();  // instantiate a GUI object 
  }
}  // end of class