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Question

In my application I am showing a clock in a TextView, and I want to update it in real time. I tried to run it like this:

public void clock() {
    while(clock_on == true) {
        executeClock();
    }
}

public void executeClock() {
    TextView timeTv = (TextView) findViewById(R.id.time);
    long currentTime=System.currentTimeMillis();
    Calendar cal=Calendar.getInstance();
    cal.setTimeInMillis(currentTime);
    String showTime=String.format("%1$tI:%1$tM %1$Tp",cal);
    timeTv.setText(showTime);
}

But it doesn't work.

"Does not work" is _never_ a sufficient problem description. http://stackoverflow.com/questions/how-to-ask — Matt Ball, Jul 30 '12 at 16:03
Have you tried looping the clock() call instead of the executeClock()? — November, Jul 30 '12 at 16:05
How about using a timer and updating your UI every second or more often if you want to .. ? Inspiration: http://stackoverflow.com/a/6702767/1525300. — wojciii, Jul 30 '12 at 16:18
Your `while` loop is too fast for the UI to update. Use a `Handler`. — slybloty, Jul 30 '12 at 16:24

Tuna Karakasoglu · Accepted Answer · 2012-07-30T16:18:06.097

4

Please Try:

private Handler handler = new Handler();
runnable.run();

private Runnable runnable = new Runnable() 
{

public void run() 
{
     //
     // Do the stuff
     //
     if(clock_on == true) {

             executeClock();

     }

     handler.postDelayed(this, 1000);
}
};

edited Jul 30 '12 at 16:18

answered Jul 30 '12 at 16:03

Tuna Karakasoglu

1,262
9
28

1

Wouldn't that call it a way too often? You have to make an if statement instead of your while. – 4ndro1d Jul 30 '12 at 16:12
1

now it seems quite right :) but I'm not sure if the @Override is missing at the run method – 4ndro1d Jul 30 '12 at 16:18

4ndro1d · Answer 2 · 2012-07-30T16:35:26.270

3

Use a Handler:

private Handler handler = new Handler() {

    @Override
    public void handleMessage(android.os.Message msg) {
            TextView timeTv = (TextView) findViewById(R.id.time);
            long currentTime=System.currentTimeMillis();
            Calendar cal=Calendar.getInstance();
            cal.setTimeInMillis(currentTime);
            String showTime=String.format("%1$tI:%1$tM %1$Tp",cal);
            timeTv.setText(showTime);

            handler.sendEmptyMessageDelayed(0, 1000);
    }
};

edited Jul 30 '12 at 16:35

answered Jul 30 '12 at 16:05

4ndro1d

2,926
7
35
65

1

This. Not only you need a handler to be able to update the textview (handlers run in UI thread) from anywhere, you can also use it to run delayed code... so instead of getting stuck in a while loop forever, simply call your clock update every 500-1000ms. – Shark Jul 30 '12 at 17:40

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