Re: Simple Java Question

=?ISO-8859-1?Q?Arne_Vajh=F8j?= <>
Fri, 02 Oct 2009 22:18:51 -0400
adric22 wrote:

However, I'm having the most difficult time finding information on how
to do what I want to do. I would rather program using the command-
line compiler if at all possible because the program I want to write
is a game and will essentially only be needing to plot pixels on the
screen and read input from the keyboard and mouse. Granted, I may
eventually want to write text on the screen or some basic shapes, but
most of what I'm going to be doing will just be plotting a screen-full
of pixels.

if anyone can point me in the right direction of a web page, or some
modern source code that just shows how to open a window of a specified
size and plot a pixel at x,y coordinates in whatever color I want...
that would be great!

Try the program below. It is rather useless in itself, but should
show something anyway.



package october;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.image.BufferedImage;

import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class DrawingFun extends JFrame {
     private DrawingField df;
     public DrawingFun() {
         getContentPane().setLayout(new BorderLayout());
         setTitle("Use arrows to move and R G B to change color");
         df = new DrawingField();
     public static void main(String[] args) {
         SwingUtilities.invokeLater(new Runnable() {
             public void run() {
                 JFrame f = new DrawingFun();

class DrawingField extends JPanel implements KeyListener {
     private final static int W = 640;
     private final static int H = 480;
     private BufferedImage img;
     private int x;
     private int y;
     private Color color;
     public DrawingField() {
         img = new BufferedImage(W, H, BufferedImage.TYPE_INT_RGB);
         Graphics g = img.getGraphics();
         g.fillRect(0, 0, W, H);
         setPreferredSize(new Dimension(W, H));
         x = 0;
         y = 0;
         color = Color.BLACK;
     protected void paintComponent(Graphics g) {
         g.drawImage(img, 0, 0, this);
     public void keyPressed(KeyEvent e) {
         int oldx = x;
         int oldy = y;
         switch(e.getKeyCode()) {
             case KeyEvent.VK_DOWN:
                 if(y < H - 1) {
                     y += 5;
             case KeyEvent.VK_UP:
                 if(y > 0) {
                     y -= 5;
             case KeyEvent.VK_LEFT:
                 if(x > 0) {
                     x -= 5;
             case KeyEvent.VK_RIGHT:
                 if(x < W - 1) {
                     x += 5;
             case KeyEvent.VK_R:
                 color = Color.RED;
             case KeyEvent.VK_G:
                 color = Color.GREEN;
             case KeyEvent.VK_B:
                 color = Color.BLUE;
         Graphics g = img.getGraphics();
         g.fillOval(Math.abs(x + oldx) / 2, Math.abs(y + oldy) / 2, 10, 10);
     public void keyReleased(KeyEvent e) {
     public void keyTyped(KeyEvent e) {

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