How to run a Runnable thread in Android?

Question

Hi

I developed one small application to display some text at defined intervals in the android emulator screen.I am using Handler class, small snippet from my code

handler=new Handler();
Runnable r=new Runnable()
{
    public void run() 
    {
        tv.append("Hello World");      
    }
};
handler.postDelayed(r, 1000);

When i run this appication the text is displayed only one time.Please any one knows how to run a thread using Handler help me.

Answer 1

The simple fix to your example is:

final Runnable r = new Runnable()
{
    public void run() 
    {
        tv.append("Hello World");
        handler.postDelayed(this, 1000);
    }
};

handler.postDelayed(r, 1000);

Or we can use normal thread for example (with original Runner):

Thread thread = new Thread()
{
    @Override
    public void run() {
        try {
            while(true) {
                sleep(1000);
                handler.post(r);
            }
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
};

thread.start();

You may consider your runnable object just as a command that can be sent to the message queue for execution, and handler as just a helper object used to send that command.

More details are here http://developer.android.com/reference/android/os/Handler.html