tabHost.setup() gives null pointer exception (Android studio)

Question

I have a very simple app which is just an activity with a tab view on it.

I have initialised and casted everything to as it should be but am continually getting a nu

Answer 1

This Line shows that the TabHost you have created is in fragment_main.xml inside layout directory which is used by PlaceholderFragment

tools:context="com.example.app.MainActivity$PlaceholderFragment"

But you are finding your TabHost in activity_main.xml

Move your code from onCreate() to onCreateView of PlaceholderFragment, below in same class if you are using default template comes with AS like

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
        Bundle savedInstanceState) {
    View rootView = inflater.inflate(R.layout.fragment_main, container, false);

    TabHost tabHost = (TabHost) rootView.findViewById(R.id.tabHost);
    tabHost.setup();

    TabHost.TabSpec spec1, spec2, spec3;

    spec1 = tabHost.newTabSpec("spec1");
    spec1.setContent(R.id.tab1);
    spec1.setIndicator("Tab1");
    tabHost.addTab(spec1);

    spec2 = tabHost.newTabSpec("spec2");
    spec2.setContent(R.id.tab2);
    spec2.setIndicator("Tab2");
    tabHost.addTab(spec2);

    spec3 = tabHost.newTabSpec("spec3");
    spec3.setContent(R.id.tab3);
    spec3.setIndicator("Tab3");
    tabHost.addTab(spec3);

   return rootView;
  }

Or If you want you can move your TabHost to activity_main.xml as well without changing the java code but that is not recommended using fragments having a lot of benefits.

Check this for benefits of using Fragments

fragment_main and activity_main layouts in Android Studio