Application.java

/*
 * This source code is a template code to make a simple GUI program like a game with JFC/Swing.
 */

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

public class Application extends JFrame {
    private AppliPanel main_panel;
    public Application() {
        super("Application Frame");
        setSize(800, 600);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        getContentPane().add(main_panel = new AppliPanel());
        setVisible(true);
    }
    private class AppliPanel extends JPanel implements KeyListener, MouseListener, MouseMotionListener, MouseWheelListener {
        private String test_message = "Click or Type!";
        public AppliPanel() {
            super(true);
            addMouseListener(this);
            addMouseMotionListener(this);
            addMouseWheelListener(this);
            addKeyListener(this);
            setFocusable(true);
        }
        @Override public void paint(Graphics g) {
            g.setColor(Color.WHITE);
            g.fillRect(0, 0, getWidth(), getHeight());
            g.setColor(Color.BLACK);
            g.setFont(g.getFont().deriveFont(50.0f));
            g.drawString("Hello, world!", 100, 150);
            if(test_message != null) {
                g.drawString(test_message, 100, 200);
            }
        }
        @Override public void keyPressed(KeyEvent evt) {}//use evt.getKeyChar() or evt.getKeyCode()
        @Override public void keyReleased(KeyEvent evt) {}
        @Override public void keyTyped(KeyEvent evt) {
            //use evt.getKeyChar(), can't use evt.getKeyCode()
            test_message = "Key "+evt.getKeyChar()+" typed";
            repaint();
        }
        @Override public void mouseClicked(MouseEvent evt) {
            if(evt.getButton() == MouseEvent.BUTTON2) {
                test_message = "Right Click at ("+evt.getX()+","+evt.getY()+")";
            } else if(evt.getClickCount() == 1) {
                test_message = "Click at ("+evt.getX()+","+evt.getY()+")";
            } else if(evt.getClickCount() == 2) {
                test_message = "Double Click at ("+evt.getX()+","+evt.getY()+")";
            }
            repaint();
        }
        @Override public void mouseDragged(MouseEvent evt) {}
        @Override public void mouseEntered(MouseEvent evt) {}
        @Override public void mouseExited(MouseEvent evt) {}
        @Override public void mouseMoved(MouseEvent evt) {}
        @Override public void mousePressed(MouseEvent evt) {}
        @Override public void mouseReleased(MouseEvent evt) {}
        @Override public void mouseWheelMoved(MouseWheelEvent evt) {}
    }
    public static void main(String[] args) {
        new Application();
    }
}