Button always null in onCreateView in a Fragment

Question

I have a cursor adapter mapped to a content provider fetching data from database and displaying it in a list view inside a fragment, all of it is working fine. Now, I need to place some buttons which will interact with a service.

Problem: The button is always returning null. Someone please let me know where I am doing wrong, but the same button click is working fine in Cursor Adapter.

fragment_track_player.xml

    <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"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="com.kavayah.spotifystreamer.TrackPlayerActivityFragment">


    <!-- TODO: Update blank fragment layout -->
    <ListView
        android:id="@+id/listview_player"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:divider="#CFD8DC"
        android:dividerHeight="1px">
    </ListView>



</RelativeLayout>

list_item_track.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">

<TextView
    android:id="@+id/artist_name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerHorizontal="true"
    android:textColor="#3399FF"
    android:textSize="10dp"
    />

<TextView
    android:id="@+id/album_name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/artist_name"
    android:layout_centerHorizontal="true"
    android:textColor="#3399FF"
    android:textSize="10dp"
    />

<ImageView
    android:id="@+id/album_icon"
    android:layout_width="200dp"
    android:layout_height="300dp"
    android:layout_below="@+id/album_name"
    android:layout_centerHorizontal="true"
    />

<TextView
    android:id="@+id/track_name"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/album_icon"
    android:layout_centerHorizontal="true"
    android:textColor="#4D4D4D"
    android:textSize="12dp"
    />

<TextView
    android:id="@+id/duration_ms"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/track_name"
    android:layout_centerHorizontal="true"
    android:textColor="#4D4D4D"
    android:textSize="12dp"
    />

<Button
    android:id="@+id/media_play"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginLeft="14dp"
    android:src="@android:drawable/ic_media_play"
    android:layout_centerHorizontal="true" />

onCreateView in fragment, play_button is always null. I tried rootView.findViewById which was also returning null, since I believe it is not defined in fragment xml, but the mListView should find it? I am missing something here.

    @Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    ....
    final View rootView = inflater.inflate(
              R.layout.fragment_track_player,   container, false);
    mListView = (ListView) rootView.findViewById(R.id.listview_player);
    mListView.setAdapter(mTrackPlayerAdapter);
    Button play_button = (Button) mListView.findViewById(R.id.media_play);
    play_button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            if (view != null) {
                Log.i(LOG_TAG, ">>>>> fragment play button click.");
            }
        }
    });

    return rootView;
}

Answer 1

You will need to set the listener in the method newView and bindView from your adapter class.

Like:

public class Adapter{
private MyFragment mFragment;
public Adapter(MyFragment mFragment){
}
  @Override
  public void bindView(View view, Context context, Cursor cursor) {
     //...
  }

  @Override
  public View newView(Context context, Cursor cursor, ViewGroup parent) {
      View view = inflater.inflate(R.layout.list_item_track, null);             
      view.findViewById(R.id.media_play).setOnClickListener( 
         new View.OnclickListener(){
             public void onClick(View v) {
                mFragment.executeWhatever();
             }
         });
      return view;
  }
}