midlet1.java~57~

J2ME的一个简单例子

package j2me;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;

public class MIDlet1 extends MIDlet implements CommandListener{
    private TextBox textBox;
    private Command okCommand = new Command("OK", Command.OK, 1);
    private Command exitCommand = new Command("EXIT", Command.EXIT, 1);
    private Display display;

    public MIDlet1() {
        //create an exclusive list
        textBox= new TextBox("Type in a 6-character word","",20,TextField.ANY);
        textBox.addCommand(okCommand);
        textBox.addCommand(exitCommand);
        textBox.setCommandListener(this);

        //retrieve display object
        display=Display.getDisplay(this);
    }

    public void startApp() throws MIDletStateChangeException {
        display.setCurrent(textBox);
    }

    /**
     * Pause the MIDlet
     */
    public void pauseApp() {
    }

    /**
     * Called by the framework before the application is unloaded
     */
    public void destroyApp(boolean unconditional) {
        textBox=null;
        okCommand = null;
        exitCommand = null;
        display=null;
    }

    public void commandAction(Command c, Displayable d) {
        if(d==textBox && c==okCommand) {
            String t=textBox.getString();
            if(t.length()==6) {
                Alert info= new Alert("Success",
                                       "Good word. Try again.",
                                       null,
                                       AlertType.INFO);
                info.setTimeout(Alert.FOREVER);
                display.setCurrent(info,textBox);
            }
            else {
                Image err_img= null;
                //create error image
                try {
                    err_img=Image.createImage("/about.png");
                }catch(Exception e){
                    System.out.println("image is not created.");
                }
                Alert error= new Alert("Error",
                                       "Sorry not right. Try again.",
                                       err_img,
                                       AlertType.ERROR);
                error.setTimeout(Alert.FOREVER);
                display.setCurrent(error,textBox);
            }
        }
        else if(c==exitCommand) {
            destroyApp(true);
            notifyDestroyed();
        }
    }
}