Listener from fragment to actvity

We need three things
– Interface
– Fragment
– Activity

Complete code in github

We create a simple Interface:

public interface InteractionListener {
    void onFragmentInteraction(String string);
}

Now in our fragment We need to use onAttach(Context context), called when a fragment is first attached to its context. In this method we init our listener

When the user click in button, we call our listener.

public class OurFragment extends Fragment implements View.OnClickListener{

    private EditText mEditText;
    private InteractionListener mListener;

    public OurFragment() {
        // Required empty public constructor
    }

    public static OurFragment newInstance() {
        OurFragment fragment = new OurFragment();
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_our, container, false);
        mEditText = (EditText) view.findViewById(R.id.fragment_our_edit_text);
        Button button = (Button) view.findViewById(R.id.fragment_our_button);
        button.setOnClickListener(this);
        return view;
    }

    public void sentString() {
        mListener.onFragmentInteraction(mEditText.getText().toString());
    }

    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof InteractionListener) {
            //init the listener
            mListener = (InteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement InteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    @Override
    public void onClick(View v) {
        sentString();
    }
}

Now in activity We implement the listener

implements InteractionListener

And then to put our method

onFragmentInteraction(String string)

 
public class MainActivity extends AppCompatActivity implements InteractionListener{
    private static final String TAG = "MainActivity";
    private MenuItem mSearchMenuItem;

    private SearchView mSearchView;
    private String mSearchString;

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

    }

    

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);

        mSearchMenuItem = menu.findItem(R.id.menu_main_action_search);

        mSearchView = (SearchView) MenuItemCompat.getActionView(mSearchMenuItem);

        focusSearView();

        return super.onCreateOptionsMenu(menu);
    }

    public void focusSearView(){
        if (mSearchString != null && !mSearchString.isEmpty()) {
            mSearchMenuItem.expandActionView();
            mSearchView.setQuery(mSearchString, true);
            mSearchView.clearFocus();
        }
    }

    public void replaceFragment() {
        Fragment OurFragment = new OurFragment().newInstance();

        try {

            FragmentManager fragmentManager = getSupportFragmentManager();
            fragmentManager.beginTransaction().replace(R.id.content_main, OurFragment, "tag").commit();

        } catch (Exception e) {
            Log.d(TAG, e.toString());
        }

    }

    @Override
    public void onFragmentInteraction(String string) {
        //listened
        mSearchString = string;
        focusSearView();
    }
}

Here activity layout:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/content_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.javier.customsearchview.MainActivity">

</RelativeLayout>

Now we create our SearchView. First we need to create new folder which name is menu.

After that we create new xml file, which name is “main”.

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/menu_main_action_search"
        android:icon="@android:drawable/ic_menu_search"
        android:title="@string/menu_main_search_title"
        app:actionViewClass="android.support.v7.widget.SearchView"
        app:showAsAction="always|collapseActionView" />
</menu>

Finally fragment layout:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.example.javier.customsearchview.OurFragment">

    <EditText
        android:id="@+id/fragment_our_edit_text"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerVertical="true"
        android:gravity="center" />

    <Button
        android:id="@+id/fragment_our_button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/fragment_our_edit_text"
        android:layout_centerHorizontal="true" />

</RelativeLayout>

Complete code in github