You can use android.os.Handler for that :
public static void startTimer(final TextView TVtime) {
duration = 10;
final Handler handler = new Handler(){
@Override
public void handleMessage(Message msg) {
TVtime.setText((String) msg.obj);
}
};
timer = new Timer();
timer.scheduleAtFixedRate(new TimerTask() {
public void run() {
Message msg = new Message();
msg.obj = setDuration();
handler.sendMessage(msg);
}
}, 1000, 1000);
}