android - Restart TimerTask Failed -

i'm writing simple code start , stop timertask. in code stop can work can not restart timertask. please me resolve problem.

my code:

public class mainactivity extends activity implements view.onclicklistener {     private timerthread timerthread;     private boolean timerhasstarted = false;     private button button;     private textview text;     private final long starttime = 1000;     private final long interval = 1;     private handler handler;     private runnable r;     private mediaplayer mp;     private timertask task;     private timer timer;     private long delay;     private boolean play = true;      @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);          setcontentview(r.layout.main);         getwindow().setflags(windowmanager.layoutparams.flag_fullscreen,                 windowmanager.layoutparams.flag_fullscreen);          button = (button) this.findviewbyid(r.id.button);         button.setonclicklistener(this);          text = (textview) this.findviewbyid(r.id.timer);         mp = mediaplayer.create(this, r.raw.cpush);         //mp.start();         delay = 1000;          timer = new timer();         timerthread = new timerthread();         timer.scheduleatfixedrate(task, 0, 10);     }      public long nextlong(random rng, long n) {         long bits, val;         {             bits = (rng.nextlong() << 1) >>> 1;             val = bits % n;         } while (bits - val + (n - 1) < 0l);         return val;     }      @override     public void onclick(view v) {         button.setbackgroundresource(r.drawable.finish);         if( play ){             play = false;             task.cancel();         }         else{             play = true;             /* restart timertask hear*/         }     }     public class timerthread extends timertask {         @override         public void run() {             random rand = new random();             final long value = nextlong(rand, 9999999999999999l);              runonuithread(new runnable() {                 @override                 public void run() {                     text.settext("" + value);                 }             });         }     } } 

a timer can't run again after has been canceled, have make new object , start new one