Q:

System.currentTimeMillis() returns same timestamp

I need to calculate time between two time. System.currentTimeMillis() returns same value everytime when it called in Thread.
My code is:
@Override
protected void onCreate(Bundle savedInstanceState) {
    // Other codes..
    start_sec = Math.round(System.currentTimeMillis()/1000);
    fin = false;
    runThread();
    // Other codes..
}

private void runThread() {
    new Thread() {
        public void run() {
            while (i++ < 61) {
                if (!running) return;
                try {
                    runOnUiThread(new Runnable() {
                        @Override
                        public void run() {
                            if(!fin){
                                int len = Math.round(System.currentTimeMillis()/1000) - start_sec;
                                Log.d("current time: ",String.valueOf(  Math.round(System.currentTimeMillis()/1000)));
                                Log.d("difference is: ", String.valueOf(len));
                                if(len < 0 && len > 58){
                                    fin=true;
                                 }
                                timerec.getLayoutParams().width = metrics.widthPixels *(60- len)/60;
                                timerec.requestLayout();
                            }
                            else{
                                end_game();
                                running= true;
                            }
                        }
                    });
                    Thread.sleep(1000);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        }
    }.start();
}

Here is the logs:
...
D/current time:: 1492337024
D/difference is:: 0
D/current time:: 1492337024
D/difference is:: 0
....

It returs same "time". What is the solution?

A:

Math.round() causes the problem.
long len = System.currentTimeMillis()/1000 - start_sec;
Log.d("current time: ",String.valueOf(System.currentTimeMillis()/1000));
Log.d("difference is: ", String.valueOf(len));

This code works altought dividing.

