Java Reference
In-Depth Information
public void run() {
Graphics g = getGraphics();
while(true) {
updateGameState(); // move computer controlled characters
moveCat();
// poll for events, move main character
doPaint();
// paint screen
try {
Thread.sleep(DELAYMS);
}
catch(InterruptedException ex) {}
}
}
}
In this more-than-pseudocode, less-than-a-game, the polling occurs in the
moveCat
method I showed you in the previous section. Once the thread is started, the thread
updates the game's characters, polls the keys, and repaints the screen every
DELAYMS
(100
milliseconds). The
updateGameState
and
doPaint
methods aren't defined yet, of course—
more on them as we continue to explore the API.
Tying Your GameCanvas to Your MIDlet
As you remember from the discussion of the
Canvas
class in Chapter 5, it and its sub-
classes implement
Displayable
, meaning you can set the
GameCanvas
subclass to be the
active
Displayable
using the
Display
's
setCurrent
method, as shown in Listing 8-3.
Listing 8-3.
Setting the GameCanvas to Be the Active Displayable
public class GameCanvasSampleMIDlet extends MIDlet {
private MyGameCanvas canvas;
public GameCanvasSampleMIDlet () {
}
private void initialize() {
canvas = new MyGameCanvas();
getDisplay().setCurrent(canvas);
canvas.start();
}
