java - Android setting action bar from child intent -

excuse me, wanted know. possible set action bar child intent?

in case, main activity sherlockactivity, it's using tab host. i'm adding tabspec intent using sherlockactivity too. , want set action bar tabspec's intent.

if possible do, may know how? because makes application meet error.

08-16 10:30:00.470: e/androidruntime(16137): caused by: java.lang.runtimeexception: unable start activity componentinfo{}: java.lang.nullpointerexception

this main activity :

public class mainactivity extends sherlockactivity {

private localactivitymanager lam; private textview tv;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.main_layout);      lam = new localactivitymanager(this, false);     lam.dispatchcreate(savedinstancestate);      getsupportactionbar().setdisplayoptions(actionbar.display_show_custom);     getsupportactionbar().setcustomview(r.layout.header);      view v = getsupportactionbar().getcustomview();     tv = (textview) v.findviewbyid(r.id.headertitle);     tv.settypeface(typeface.createfromasset(alumniapplication.getcontext().getassets(), "fonts/llnitro_.ttf"));     tv.settext("title");      settab(); }  private void settab(){           tabhost tabhost = (tabhost) findviewbyid(r.id.main_tabhost);     tabhost.setup(lam);      tabspec com = tabhost.newtabspec("community");     com.setindicator(gettabindicator(r.drawable.com_tab));     com.setcontent(new intent(alumniapplication.getcontext(), communityactivity.class));      tabhost.addtab(com); }  private view gettabindicator(int srcid){     view v = layoutinflater.from(alumniapplication.getcontext()).inflate(r.layout.tab_image_layout, null);      imageview iv = (imageview) v.findviewbyid(r.id.tab_image);     iv.setimageresource(srcid);      return v; } 

}

and wanted set the action bar child intent

public class communityactivity extends sherlockactivity {

private localactivitymanager lam;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.tab_above_layout); } 

}

but when that, gone error.

if want call method of activity (which hosting fragment) out of child-fragment, need refernece hosting activity. getactivity() can connection. can call methods of activity inside fragment.

for example:

getactivity().settitle(r.string.my_actionbar_title);