manyballs.java

J2ME编写的手机上的一个小游戏---Balls

package balls;

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

import balls.About;

public class ManyBalls extends MIDlet implements CommandListener {

    Display display;
    ManyCanvas canvas;		// The main screen
    private Command exitCommand = new Command("Exit", Command.EXIT, 99);
    private Command toggleCommand = new Command("Stop/Go", Command.SCREEN, 1);
    private Command helpCommand = new Command("Help", Command.HELP, 2);
    private Command aboutCommand = new Command("About", Command.HELP, 30);
    private Form helpScreen;
    private String helpText = "^ = faster\n v = slower\n < = fewer\n> = more";


    // the GUI buttons
    //	Button exitButton, clearButton, moreButton, lessButton;

    /*
     * Create the canvas
     */
    public ManyBalls() {
        display = Display.getDisplay(this);

        canvas = new ManyCanvas(display, 40);
        canvas.addCommand(exitCommand);
        canvas.addCommand(toggleCommand);
        canvas.addCommand(helpCommand);
        canvas.addCommand(aboutCommand);
        canvas.setCommandListener(this);
    }

    public void startApp() throws MIDletStateChangeException {
        canvas.start();
    }

    public void pauseApp() {
        canvas.pause();
    }

    public void destroyApp(boolean unconditional)
        throws MIDletStateChangeException {
        canvas.destroy();
    }

    /*
     * Respond to a command issued on the Canvas.
     */
    public void commandAction(Command c, Displayable s) {
        if (c == toggleCommand) {
            if (canvas.isPaused())
                canvas.start();
            else
                canvas.pause();
        } else if (c == helpCommand) {
            canvas.pause();
            showHelp();
        } else if (c == exitCommand) {
            try {
                destroyApp(false);
                notifyDestroyed();
            } catch (MIDletStateChangeException ex) {
            }
        } else if (c == aboutCommand) {
            About.showAbout(display);
        }
    }

    /*
     * Put up the help screen. Create it if necessary.
     * Add only the Resume command.
     */
    void showHelp() {
        if (helpScreen == null) {
            helpScreen = new Form("Many Balls Help");
            helpScreen.append("^ = faster\n");
            helpScreen.append("v = slower\n");
            helpScreen.append("< = fewer\n");
            helpScreen.append("> = more\n");
        }
        helpScreen.addCommand(toggleCommand);
        helpScreen.setCommandListener(this);
        display.setCurrent(helpScreen);
    }



}