getChildFragmentManager - New Dev Point

getChildFragmentManager() on programmatically (dynamically) added Fragments?

accepted

In conclusion, I want to reference OuterFrag in MainActivity always. And I want OuterFrag act as a placeholder to load different InnerFrags. In short, I want to call getChildFragmentManager() in OuterFrag, when it is added programmatically (dynamically).

If you want this then make your OuterFrag have a container layout as its content and add whatever InnerFrag to that container. The layout file for the OuterFrag will be:

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/fragContainer"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
/>

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:id="@+id/fragContainer"

android:layout_width="match_parent"

android:layout_height="match_parent"

Of course you could have other views in the layout for the OuterFrag if you want that. Then your addInnerFrag method will be:

public void addInnerFrag() {
        getChildFragmentManager().beginTransaction().add(R.id.fragContainer, new InnerFrag()).commit();
        getChildFragmentManager().executePendingTransactions();
}

public void addInnerFrag() {

getChildFragmentManager().beginTransaction().add(R.id.fragContainer, new InnerFrag()).commit();

getChildFragmentManager().executePendingTransactions();

}

The code for adding the OuterFrag to the main activity remains valid.