Start service from the same activity in android -

i have class extend intent service. want start service activity erroor:

    intent msgintent = new intent();     msgintent.setclass(testactivity, testactivity.class);     startservice(msgintent);  07-15 11:53:33.030: e/androidruntime(28989): java.lang.nullpointerexception 07-15 11:53:33.030: e/androidruntime(28989):    @ android.content.contextwrapper.getapplicationcontext(contextwrapper.java:109) 

how can start service same activity?

intent msgintent = new intent(yourclass.this, testservice.class); startservice(msgintent);