java - How can i make that in the timer my program will do something every second? -

in top of mainactivity.java added:

private handler customhandler = new handler(); long timeswapbuff = 0l; 

then inside oncreate did:

@override     protected void oncreate(bundle savedinstancestate)     {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);          starttime = systemclock.uptimemillis(); customhandler.postdelayed(updatetimerthread,0);          timervalue = (textview) findviewbyid(r.id.timervalue);          startbutton = (button) findviewbyid(r.id.startbutton);          startbutton.setonclicklistener(new view.onclicklistener() {              public void onclick(view view) {                 starttime = systemclock.uptimemillis();                 customhandler.postdelayed(updatetimerthread, 0);              }         });          pausebutton = (button) findviewbyid(r.id.pausebutton);         pausebutton.setonclicklistener(new view.onclicklistener() {              public void onclick(view view) {                 customhandler.removecallbacks(updatetimerthread);              }         }); 

then in updatetimerthread:

private runnable updatetimerthread = new runnable() {          public void run() {              long updatedtime = 0l;             long timeinmilliseconds = 0l;             timeinmilliseconds = systemclock.uptimemillis() - starttime;//system.currenttimemillis() - starttime;             updatedtime = timeswapbuff + timeinmilliseconds;              int secs = (int) (updatedtime / 1000);             int mins = secs / 60;             secs = secs % 60;             int milliseconds = (int) (updatedtime % 1000);             timervalue.settext("" + mins + ":"                     + string.format("%02d", secs) + ":"                     + string.format("%03d", milliseconds));             customhandler.postdelayed(this, 0);         }      }; 

now each time run program start timer start 00:00:00

now want add somehow each second something. not reset timer not pause or stop let keep running each second want else in program.

the problem how check every second ?