How can I implement FragmentManager and FragmentTransaction to replace just a single fragment?

Question

I have an activity with 3 fragments; a header; a body; a footer (same point as in HTML). The bodyfragment contains three buttons which each should replace the middle fragmen

Answer 1

You use the FragmentManager like this:

FragmentManager manager = getFragmentManager();
FragmentTransaction transaction = manager.beginTransaction();
transaction.replace(R.id.bodyfragment, AnotherFragment.newInstance()); // newInstance() is a static factory method.
transaction.commit();

This code would replace the Fragment which sits in the View with the id R.id.bodyfragment with a new Instance of another Fragment.

EDIT:

To create a new instance of another Fragment a static factory method is supposed to be used. You would implement them in your Fragment like this:

public class AnotherFragment extends Fragment {

    public static AnotherFragment newInstance() {
        AnotherFragment fragment = new AnotherFragment();
        ...
        // do some initial setup if needed, for example Listener etc
        ...
        return fragment;
    }
    ...
}