android - unable to start activity componentinfo - beginTransaction.add -

as title says getting unable start activity error.

i commented part gets me error.

new android, not sure if i'm supposed upload other code, or method messes things up.

import android.app.activity; import android.app.fragment; import android.os.bundle; import android.util.log; import android.view.menu; import android.view.menuitem; import android.widget.toolbar;  import com.dan190.tasks.r; import com.dan190.tasks.fragment.taskeditfragment;  public class taskeditactivity extends activity {  public static final string extra_taskid = "taskid"; @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);      setcontentview(r.layout.activity_task_edit);     setactionbar((toolbar) findviewbyid(r.id.toolbar));      long id = getintent().getlongextra(taskeditactivity.extra_taskid, 0l);     fragment fragment = taskeditfragment.newinstance(id);     string fragment_tag = taskeditfragment.default_fragment_tag;  /*this part messes  *it works fine if delete following if-block  */     if (savedinstancestate == null) {         getfragmentmanager().begintransaction().add(                 r.id.container,                 fragment,                  fragment_tag).commit();      } } } 

edit: here error message.

07-14 00:07:41.666  13945-13945/com.dan190.tasks e/androidruntime﹕ fatal exception: main process: com.dan190.tasks, pid: 13945 java.lang.runtimeexception: unable start activity componentinfo{com.dan190.tasks/com.dan190.tasks.activity.taskeditactivity}: java.lang.illegalargumentexception: target must not null.         @ android.app.activitythread.performlaunchactivity(activitythread.java:2712)         @ android.app.activitythread.handlelaunchactivity(activitythread.java:2777)         @ android.app.activitythread.access$900(activitythread.java:179)         @ android.app.activitythread$h.handlemessage(activitythread.java:1462)         @ android.os.handler.dispatchmessage(handler.java:102)         @ android.os.looper.loop(looper.java:145)         @ android.app.activitythread.main(activitythread.java:5972)         @ java.lang.reflect.method.invoke(native method)         @ java.lang.reflect.method.invoke(method.java:372)         @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1399)         @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1194)  caused by: java.lang.illegalargumentexception: target must not null.         @ com.squareup.picasso.requestcreator.into(requestcreator.java:553)         @ com.squareup.picasso.requestcreator.into(requestcreator.java:536)         @ com.dan190.tasks.fragment.taskeditfragment.oncreate(taskeditfragment.java:56)         @ android.app.fragment.performcreate(fragment.java:2075)         @ android.app.fragmentmanagerimpl.movetostate(fragmentmanager.java:868)         @ android.app.fragmentmanagerimpl.movetostate(fragmentmanager.java:1082)         @ android.app.backstackrecord.run(backstackrecord.java:833)         @ android.app.fragmentmanagerimpl.execpendingactions(fragmentmanager.java:1467)         @ android.app.activity.performstart(activity.java:6328)         @ android.app.activitythread.performlaunchactivity(activitythread.java:2675) @ android.app.activitythread.handlelaunchactivity(activitythread.java:2777) @ android.app.activitythread.access$900(activitythread.java:179) @ android.app.activitythread$h.handlemessage(activitythread.java:1462) @ android.os.handler.dispatchmessage(handler.java:102)     @ android.os.looper.loop(looper.java:145) @ android.app.activitythread.main(activitythread.java:5972) @ java.lang.reflect.method.invoke(native method) @ java.lang.reflect.method.invoke(method.java:372) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1399) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1194)