When I run my app, MainFragment does not show up at all in the activity extending ActionBarActivity. I did check this post, but it didn't help me resolve my problem. Here's my activity and fragment:

activity_main.xml:

public class MainActivity extends ActionBarActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); if (savedInstanceState == null) { getFragmentManager().beginTransaction() .add(R.id.container, new MainFragment()) .commit(); } Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); setSupportActionBar(toolbar); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } }

fragment_main.xml:

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

I don't think I need to reference any xml here... everything was working fine until I extended ActionBarActivity instead of Activity in activity_main.xml.

EDIT: Added xml just in case:

activity_main.xml:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/container" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity" tools:ignore="MergeRootFrame" > <include layout="@layout/toolbar" /> </LinearLayout>

fragment_main.xml:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".MainActivity$PlaceholderFragment"> // There are several text views and buttons I will not add to this code, // but just know that this fragment isn't blank. </RelativeLayout>

EDIT 2: I've done some testing and whenever I remove the toolbar from the activity_main.xml, the fragment shows up, along with no action bar (since that is the theme I have set to my app in order to use the toolbar). So here is the xml for my toolbar.xml as well, which I use in activity_main.xml. Maybe I've done something wrong for it to hide my entire fragment?

tl;dr: fragment shows when this line of code is removed from activity_main.xml:

<include layout="@layout/toolbar" />

and this one in activity_main.xml: