J2ME Timer 使用指南_JSP教程

import javax.microedition.midlet.*; import javax.microedition.lcdui.*; import java.util.*; public class TimerDemo extends MIDlet { Display display; StarField field = new StarField(); FieldMover mover = new FieldMover(); Timer timer = new Timer(); public TimerDemo() { display = Display.getDisplay( this ); } protected void destroyApp( boolean unconditional ) { } protected void startApp() { display.setCurrent( field ); timer.schedule( mover, 100, 100 ); } protected void pauseApp() { } public void exit(){ timer.cancel(); // stop scrolling destroyApp( true ); notifyDestroyed(); } class FieldMover extends TimerTask { public void run(){ field.scroll(); } } class StarField extends Canvas { int height; int width; int[] stars; Random generator = new Random(); boolean painting = false; public StarField(){ height = getHeight(); width = getWidth(); stars = new int[ height ]; for( int i = 0; i < height; i ){ stars[i] = -1; } } public void scroll() { if( painting ) return; for( int i = height-1; i > 0; --i ){ stars[i] = stars[i-1]; } stars[0] = ( generator.nextInt() % ( 3 * width ) ) / 2; if( stars[0] >= width ){ stars[0] = -1; } repaint(); } protected void paint( Graphics g ){ painting = true; g.setColor( 0, 0, 0 ); g.fillRect( 0, 0, width, height ); g.setColor( 255, 255, 255 ); for( int y = 0; y < height; y ){ int x = stars[y]; if( x == -1 ) continue; g.drawline( x, y, x, y ); } painting = false; } protected void keypressed( int keycode ){ exit(); } } }