How to add fragment activity to activity?

How do I add a Fragment to an Activity with a programmatically created content view

• I want to add a Fragment to an Activity that implements its layout programatically. I looked over the Fragment documentation but there aren't many examples describing what I need. Here is the type of code I tried to write: public class DebugExampleTwo extends Activity { private ExampleTwoFragment mFragment; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); FrameLayout frame = new FrameLayout(this); if (savedInstanceState == null) { mFragment = new ExampleTwoFragment(); FragmentTransaction ft = getFragmentManager().beginTransaction(); ft.add(frame.getId(), mFragment).commit(); } setContentView(frame); } } class ExampleTwoFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { Button button = new Button(getActivity()); button.setText("Hello There"); return button; } } This code compiles but crashes at start, probably because my FragmentTransaction.add() is incorrect. What is the correct way to do this?

• Answer:

  It turns out there's more than one problem with that code. A fragment cannot be declared that way, inside the same java file as the activity but not as a public inner class. The framework expects the fragment's constructor (with no parameters) to be public and visible. Moving the fragment into the Activity as an inner class, or creating a new java file for the fragment fixes that. The second issue is that when you're adding a fragment this way, you must pass a reference to the fragment's containing view, and that view must have a custom id. Using the default id will crash the app. Here's the updated code: public class DebugExampleTwo extends Activity { private static final int CONTENT_VIEW_ID = 10101010; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); FrameLayout frame = new FrameLayout(this); frame.setId(CONTENT_VIEW_ID); setContentView(frame, new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)); if (savedInstanceState == null) { Fragment newFragment = new DebugExampleTwoFragment(); FragmentTransaction ft = getFragmentManager().beginTransaction(); ft.add(CONTENT_VIEW_ID, newFragment).commit(); } } public static class DebugExampleTwoFragment extends Fragment { @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { EditText v = new EditText(getActivity()); v.setText("Hello Fragment!"); return v; } } }