windowlistenerdemo2.java

java编程代码

import javax.swing.JFrame;
import javax.swing.JPanel;
import java.awt.BorderLayout;
import java.awt.FlowLayout;
import java.awt.Color;
import javax.swing.JLabel;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.WindowEvent;
import java.awt.event.WindowAdapter;


public class WindowListenerDemo2 extends JFrame
{
    public static final int WIDTH = 300; //for main window
    public static final int HEIGHT = 200; //for main window
    public static final int SMALL_WIDTH = 200; //for confirm window
    public static final int SMALL_HEIGHT = 100;//for confirm window

    private class CheckOnExit extends WindowAdapter
	{
	    public void windowClosing(WindowEvent e)
	    {
	        ConfirmWindow checkers = new ConfirmWindow( );
	        checkers.setVisible(true);
	    }
    } //End of inner class CheckOnExit

    private class ConfirmWindow extends JFrame implements ActionListener
    {
        public ConfirmWindow( )
        {
            setSize(SMALL_WIDTH, SMALL_HEIGHT);
            getContentPane( ).setBackground(Color.YELLOW);
            setLayout(new BorderLayout( ));

            JLabel confirmLabel = new JLabel(
                           "Are you sure you want to exit?");
            add(confirmLabel, BorderLayout.CENTER);

            JPanel buttonPanel = new JPanel( );
            buttonPanel.setBackground(Color.ORANGE);
            buttonPanel.setLayout(new FlowLayout( ));

            JButton exitButton = new JButton("Yes");
            exitButton.addActionListener(this);
            buttonPanel.add(exitButton);

            JButton cancelButton = new JButton("No");
            cancelButton.addActionListener(this);
            buttonPanel.add(cancelButton);

            add(buttonPanel, BorderLayout.SOUTH);
        }

        public void actionPerformed(ActionEvent e)
        {
            String actionCommand = e.getActionCommand( );

            if (actionCommand.equals("Yes"))
                System.exit(0);
            else if (actionCommand.equals("No"))
                dispose( );//Destroys only the ConfirmWindow.
            else
                System.out.println("Unexpected Error in Confirm Window.");
        }
    } //End of inner class ConfirmWindow

    public static void main(String[] args)
    {
        WindowListenerDemo demoWindow = new WindowListenerDemo( );
        demoWindow.setVisible(true);
    }

    public WindowListenerDemo2( )
    {
        setSize(WIDTH, HEIGHT);
        setTitle("Window Listener Demonstration");

        setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
        addWindowListener(new CheckOnExit( ));

        getContentPane( ).setBackground(Color.LIGHT_GRAY);
        JLabel aLabel = new JLabel("I like to be sure you are sincere.");
        add(aLabel);
    }
}