J2ME画布上的倒数计时器

Question

In my Application, I need the Countdown timer(like a chronometer in Android) which is implemented on Canvas and display the countdown time to the user. How can I implement Countdown Timer on Canvas and display the Countdown time to the user?

Answer 1

Its very easy, you simply need to use two classes TimerTask and Timer class. The TimerTask class is a thread which will execute your particular code while Timer is the class which tells TimerTask when to perform the code defined init. Just study the following code,

import java.util.Timer;
import java.util.TimerTask;

public class TimerDemo
{
    private MyTimerTask mt;
    private Timer timer;

    public TimerDemo()
    {
        mt = new MyTimerTask();     
        timer = new Timer(); 
        timer.schedule(mt, 1000, 1000);
        System.out.println ( "Countdown Begins " ); 
    }

    public static void main ( String args[] )
    {
        TimerDemo td = new TimerDemo();
    }

    private class MyTimerTask extends TimerTask
    {
        int val = 10;
        public void run()
        {
            if ( val > 0 )
            {
                System.out.println ( "Value : " + val-- );
            }
            else
            {
                timer.cancel();
            }
        }
    }
}

/*************************/
/**********OUTPUT*********
Countdown Begins 
Value : 10
Value : 9
Value : 8
Value : 7
Value : 6
Value : 5
Value : 4
Value : 3
Value : 2
Value : 1
*************************/

Answer 2

You need to use java.util.TimerTask or java.util.Timer and implement The Runnable interface to create a thread. Google it and see the documentation.