Unable to hide a Fragment with Fragment Manager

Question

I am trying to hide a Fragment when my activity starts, my layout is as follows:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:background="#eee"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

<fragment android:name="com.TypeFragment"
          android:id="@+id/type_fragment"
          android:layout_width="184dp"
          android:layout_alignParentLeft="true"
          android:layout_height="wrap_content" 
          android:text="@string/type"
          />

<fragment android:name="com.ModeFragment"
          android:id="@+id/mode_fragment"
          android:layout_below="@id/type_fragment"
          android:layout_width="184dp"
          android:layout_alignParentLeft="true"
          android:layout_height="wrap_content" 
          android:text="@string/mode"
          />
<fragment
    android:id="@+id/canvas_fragment"
    android:name="com.CanvasFragment"
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:layout_alignParentRight="true"
    android:layout_alignParentTop="true"
    android:layout_toRightOf="@+id/type_fragment" />

<fragment android:name="com.NumericsInputFragment"
    android:id="@+id/numeric_area"
    android:layout_below="@id/mode_fragment"
    android:layout_width="184dp"
    android:layout_height="wrap_content" />

</RelativeLayout>

My MainActivity extends FragmentActivity and has the following onCreate

    @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_canvas);

    Log.d("ACTIVITY" ,  "linside");
    // Check which layout we are using
    if(findViewById(R.id.fragment_container) != null) {
        /* if it is restored from a previous state - simply return */
         if (savedInstanceState != null) {
                return;
            }
         /* Create a TypeFragment */
         TypeFragment firstFragment = new TypeFragment();
         //firstFragment.getView().setBackgroundColor(Color.GRAY);
         ModeFragment secondFragment = new ModeFragment();
         /* This is the numerics Fragement */
         NumericsInputFragment numericsFragment = new NumericsInputFragment();

         /* Pass the Intents Extras to the Fragment */
         firstFragment.setArguments(getIntent().getExtras());
         secondFragment.setArguments(getIntent().getExtras());

         /* Add the fragment to the fragment container */
         getSupportFragmentManager().beginTransaction()
            .add(R.id.fragment_container, firstFragment, null)
            .add(R.id.fragment_container, secondFragment, null)
            .add(R.id.fragment_container, numericsFragment, null)
            .commit();

         FragmentTransaction transaction = getFragmentManager().beginTransaction();
            transaction.hide(getFragmentManager().findFragmentById(R.id.numeric_area));
            transaction.commit();
    }
}

Nothing I do seems to make a difference to my initial layout. I.e if I remove all of the .add() statements I still get the same layout. Obviously I am doing something very wrong here, can someone shed some light on what I might be doing incorrectly ?

EDIT

I have replaced the layout with an updated version, replacing the dynamic Fragment with a FrameLayout like so :

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="horizontal"
android:background="#eee"
android:layout_width="match_parent"
android:layout_height="match_parent">

<fragment android:name="com.TypeFragment"
          android:id="@+id/type_fragment"
          android:layout_width="184dp"
          android:layout_alignParentLeft="true"
          android:layout_height="wrap_content" 
          android:text="@string/type"
          />

<fragment android:name="com.ModeFragment"
          android:id="@+id/mode_fragment"
          android:layout_below="@id/type_fragment"
          android:layout_width="184dp"
          android:layout_alignParentLeft="true"
          android:layout_height="wrap_content" 
          android:text="@string/mode"
          />
<fragment
    android:id="@+id/canvas_fragment"
    android:name="com.CanvasFragment"
    android:layout_width="wrap_content"
    android:layout_height="fill_parent"
    android:layout_alignParentRight="true"
    android:layout_alignParentTop="true"
    android:layout_toRightOf="@+id/type_fragment" />

<FrameLayout 
    android:id="@+id/numeric_area"
    android:layout_width="184dp"
    android:layout_height="match_parent"
    android:layout_below="@id/mode_fragment"
    android:background="?android:attr/detailsElementBackground"
/>
</RelativeLayout>

I can then control if this is displayed as described here http://developer.android.com/guide/components/fragments.html

Answer 1

You cannot add/replace/hide fragments that you define statically in layout files. You can use Framelayout and replace it with fragment instances using FragmentManager/FragmentTransaction. Check out this link