Thought i’d make a quick post as part of a reminder for me or for those coming from ActionScript to Android and wondering how to create a Timer. It’s no secret but took me some searching to find (what i think is) the correct way to use timers in Android while i was working on some stuff for MassRoute.

Within the Android SDK there is a Handler class. I won’t go into the specifics of Handler as there is a pretty good explanation within the documentation, but the basics is that you pass a Runnable object that will be invoked at a given time.

To run the timer once:

protected Handler taskHandler = new Handler();
protected void setTimer( long time )
{
    Runnable t = new Runnable() {
    public void run()
    {
        runNextTask();
    }
    };
    taskHandler.postAtTime( t, time );
}

protected void runNextTask()
{
    // run my task.
}

[UPDATE 10/20/2010: After talking with Jesse Freeman over continuous delayed timers in using Runnable in Android development, we discovered that the previous solution didn't quite go the whole mile. This example has been updated to provide a continuous delayed timer that stops based on a flag]

To run the timer continuously at a given time:

// -- Class Members --
protected Handler taskHandler = new Handler();
protected Boolean isComplete = false;

// -- Set Timer --
protected void setTimer( long time )
{
    final long elapse = 1000;
    Runnable t = new Runnable() {
        public void run()
        {
            runNextTask();
            if( !isComplete )
            {
                _taskHandler.postDelayed( this, elapse );
            }
        }
    };
    _taskHandler.postDelayed( t, elapse );
}

protected void runNextTask()
{
    // run my task.
    // determine isComplete.
}

Posted in Android.