title: Fragment can not be cast to android.support.v4.app.Fragment
body: <p>I am getting this error while implementing Fragment tabhost.</p>
  
  <p>I am basically trying to call an activity in tab view which extends Fragment.</p>
  
  <p>I also tried with extending FragmentActivity, but it gives an error on "onCreateView" method.
  Upon removing @override annotation from "onCreateView" method, and running the app lead to following error.</p>
  
  <pre><code>    11-27 20:54:06.937: E/AndroidRuntime(4255): FATAL EXCEPTION: main
      11-27 20:54:06.937: E/AndroidRuntime(4255): java.lang.ClassCastException: com.variouscal.calculators.FragmentTab1 cannot be cast to android.support.v4.app.Fragment
      11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.support.v4.app.Fragment.instantiate(Fragment.java:394)
      11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.support.v4.app.FragmentTabHost.doTabChanged(FragmentTabHost.java:339)
      11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.support.v4.app.FragmentTabHost.onTabChanged(FragmentTabHost.java:307)
      11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.widget.TabHost.invokeOnTabChangeListener(TabHost.java:391)
      11-27 20:54:06.937: E/AndroidRuntime
  
  (4255):     at android.widget.TabHost.setCurrentTab(TabHost.java:376)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.widget.TabHost$2.onTabSelectionChanged(TabHost.java:150)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.widget.TabWidget$TabClickListener.onClick(TabWidget.java:546)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.view.View.performClick(View.java:4084)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.view.View$PerformClick.run(View.java:16966)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.os.Handler.handleCallback(Handler.java:615)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.os.Handler.dispatchMessage(Handler.java:92)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.os.Looper.loop(Looper.java:137)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at android.app.ActivityThread.main(ActivityThread.java:4931)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at java.lang.reflect.Method.invokeNative(Native Method)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at java.lang.reflect.Method.invoke(Method.java:511)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:791)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:558)
  11-27 20:54:06.937: E/AndroidRuntime(4255):     at dalvik.system.NativeStart.main(Native Method)
  </code></pre>