What can be the difference of using a fragment and frameLayout in android? Can both be used interchangeably?

Question

I have seen an approach where frameLayout is used in case of fragments. The ultimate goal was to have multiple fragments.

Answer 1

For showing a single Fragment immediately on the screen, yes, you can use fragment or FrameLayout interchangeably.

Single Fragment, Method 1

Showing the Fragment via the fragment tag would look like this in XML:

<fragment class="com.example.ExampleFragment"
        android:id="@+id/details" android:layout_weight="1"
        android:layout_width="0px" android:layout_height="match_parent" />

Single Fragment, Method 2

Showing the Fragment via FrameLayout would look like this in XML:

<FrameLayout android:id="@+id/details" android:layout_weight="1"
            android:layout_width="0px" android:layout_height="match_parent" />

Followed by Java code like this:

Fragment newFragment = new ExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.replace(R.id.details, newFragment);
transaction.addToBackStack(null);
transaction.commit();

Multiple Fragments

Method 2 then supports changing what fragment you are showing later by running more Java code to change what Fragment is there afterwards:

Fragment secondFragment = new SecondExampleFragment();
FragmentTransaction transaction = getFragmentManager().beginTransaction();
transaction.replace(R.id.details, secondFragment);
transaction.addToBackStack(null);
transaction.commit();

So FrameLayout gives you the extra ability to do that over using the fragment tag.