Show/Hide Fragments and change the visibility attribute programmatically

Question

This is a 2 part problem. What I\'m having is a 3 Fragment layout where the 3\'rd Fragment(FragmentC) is added dynamically when the user taps a button found in another fragm

Answer 1

In FragmentB you're trying get a view which is not on your contentView

public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    View view = inflater.inflate(R.layout.fragment_b, container, false);

    // this is in fragment_b layout
    ListView listView = (ListView) view.findViewById(R.id.listView1);
    Button button = (Button) view.findViewById(R.id.button);

    /* ... */
    // ****************************************
    // this is NOT in fragment_b layout, which causes null
    // ****************************************
    final FrameLayout frameLayout = (FrameLayout) view.findViewById(R.id.fragment_C);

    /* ... */
}

Try:

    final FrameLayout frameLayout = (FrameLayout) getActivity().getWindow().findViewById(R.id.fragment_C);

Whereas R.id.fragment_C is inflated and setted on MainActivity.

Moreover, I had the same problem until use an extra flag

    FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
    final Fragment fragmentC = new FragmentC();
    fragmentTransaction.add(R.id.fragment_C, fragmentC);
    fragmentTransaction.commit();
    menuIsOn = false;

    final View fragmentCView = findViewById(R.id.fragment_C);

    final Button btn = (Button) findViewById(R.id.btn);
    btnPowers.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            if (!menuIsOn) {
                fragmentCView.setVisibility(View.VISIBLE);
            } else {
                fragmentCView.setVisibility(View.INVISIBLE);
            }
            menuIsOn = !menuIsOn;
        }
    });

Answer 2

Create the Instances of fragments and add instead of replace

        FragA  fa= new FragA();
        FragB  fb= new FragB();
        FragC  fc= new FragB();
        fragmentManager = getSupportFragmentManager();
        fragmentTransaction = fragmentManager.beginTransaction();
        fragmentTransaction.add(R.id.fragmnt_container, fa);
        fragmentTransaction.add(R.id.fragmnt_container, fb);
        fragmentTransaction.add(R.id.fragmnt_container, fc);
        fragmentTransaction.show(fa);
        fragmentTransaction.hide(fb);
        fragmentTransaction.hide(fc);
        fragmentTransaction.commit();

suppose we want to to hide and show different fragments based on our action

    fragmentTransaction = fragmentManager.beginTransaction();
    fragmentTransaction.hide(fa);
    fragmentTransaction.show(fb);
    fragmentTransaction.hide(fc);
    fragmentTransaction.commit();