android - vibrator not working in drag mode( Fatal Exception ) -

i have subclass(extends activity) , drag activity happen in class, in drag mode can not use vibrator , fatal exception:

case dragevent.action_drag_location: int idv = (integer) v.getid(); if( idv==100) { mainactivity.btdel.setbackgroundresource(r.drawable.rounded); vibrator vib = (vibrator)     getsystemservice(getapplicationcontext().vibrator_service); vib.vibrate(500); return true; } ....... 

could please me.

to perform vibration should this:

import android.os.vibrator; 

then in on create

vibrator v = (vibrator) this.context.getsystemservice(context.vibrator_service); 

then vibrate

// vibrate 500 milliseconds   v.vibrate(500); 

include permission in androidmanifest.xml file:

<uses-permission android:name="android.permission.vibrate"/>