start chronometer from dialog box -

i chronometer start when click "ok" button dialogbox... can not. succeed start chronometer when dialog box open. when click "ok" button time has passed...

thanks help... begin code.

my code:

    import android.app.activity;     import android.app.dialog;     import android.os.bundle;     import android.os.systemclock;     import android.view.view;     import android.view.view.onclicklistener;     import android.widget.button;     import android.widget.chronometer;     import android.widget.textview;   public class activityone extends activity implements onclicklistener {  private chronometer mychronometer;  @override  public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.timerlayout);      mychronometer = (chronometer) findviewbyid(r.id.chronometer);      button buttonstart = (button) findviewbyid(r.id.startbutton);     button buttonstop = (button) findviewbyid(r.id.pausebutton);     button buttonreset = (button) findviewbyid(r.id.resetbutton);       buttonstart.setonclicklistener(this);     buttonstop.setonclicklistener(this);     buttonreset.setonclicklistener(this);     final dialog dialog = new dialog(activityone.this, r.style.dialogchrono); dialog.setcontentview(r.layout.dialogchrono);  dialog.settitle("titre"); textview txt = (textview) dialog.findviewbyid(r.id.textview4); textview txt1 = (textview) dialog.findviewbyid(r.id.textview1); textview txt2 = (textview) dialog.findviewbyid(r.id.textview2); textview txt3 = (textview) dialog.findviewbyid(r.id.textview3);  txt1.settext("texte1"); txt2.settext("texte2"); txt3.settext("texte3"); txt.settext("texte");      button dismissbutton = (button) dialog.findviewbyid(r.id.button); dismissbutton.setonclicklistener(new view.onclicklistener() {      @override     public void onclick(view v) {         dialog.dismiss();         } });         dialog.show(); } @override public void onclick(view v) {      switch (v.getid()) {         case r.id.startbutton:             mychronometer.start();             break;         case r.id.pausebutton:             mychronometer.stop();             break;         case r.id.resetbutton:             mychronometer.setbase(systemclock.elapsedrealtime());             break;     } } }