android - Recyclerview(Getting item on Recyclerview)

Question

I've implemented SearchView + Recyclerview using this on github. GITHUB
My next step is to get the item on selected part on the recyclerview.
Then I saw some code getting the child on recyclerview.
The code is working when the getChildAt(index) =0.
But when i put on index=12 or greater than that.
The program crashed.

mRecyclerView.setAdapter(mAdapter);
        mRecyclerView.addOnItemTouchListener(
                new RecyclerItemClickListener(getContext(), new RecyclerItemClickListener.OnItemClickListener() {
                    @Override
                    public void onItemClick(View view, int position) {
                        final int valueThisIteration = position;
                        mRecyclerView.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
                            @Override
                            public void onGlobalLayout() {
                                TextView textViewDrawerTitle = (TextView) mRecyclerView.getChildAt(valueThisIteration).findViewById(R.id.tvText);
                                textViewDrawerTitle.setText("Checked");
                                mRecyclerView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                            }
                        });

                    }
                })
        );

And im getting this error.

11-04 09:36:02.818 1629-1629/? E/AndroidRuntime: FATAL EXCEPTION: main
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime: Process: com.thesis.juandirection.juandirectionfinale, PID: 1629
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.View.findViewById(int)' on a null object reference
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at com.thesis.juandirection.juandirectionfinale.fragments.FragmentSearch$1$1.onGlobalLayout(FragmentSearch.java:94)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.view.ViewTreeObserver.dispatchOnGlobalLayout(ViewTreeObserver.java:815)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1867)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1054)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:5779)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.view.Choreographer$CallbackRecord.run(Choreographer.java:767)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.view.Choreographer.doCallbacks(Choreographer.java:580)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.view.Choreographer.doFrame(Choreographer.java:550)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:753)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.os.Handler.handleCallback(Handler.java:739)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.os.Handler.dispatchMessage(Handler.java:95)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.os.Looper.loop(Looper.java:135)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at android.app.ActivityThread.main(ActivityThread.java:5221)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Native Method)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at java.lang.reflect.Method.invoke(Method.java:372)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:899)
11-04 09:36:02.818 1629-1629/? E/AndroidRuntime:     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:694)

Answer 1

For handling item clicks in a RecyclerView, I recommend you move your logic into the ViewHolder of your Adapter. You can have your ViewHolder implement View.OnClickListener, and override the onClick() method to preform an action. If your action depends on the item clicked, you can reference it using getAdapterPosition(). The code will look something like this:

public class MyViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {
   public MyViewHolder(View view) {
      super(view);

      view.setOnClickListener(this);
   }

   @Override
   public void onClick(View view) {
      // Get the item clicked
      // For this example, I'm assuming your data source is of type `List<MyObject>`
      MyObject myObject = mDataSource.get(getAdapterPosition());
      // Then you can do any actions on it, for example: 
      myObject.setChecked();
   }
}

Clearly the logic that happens inside onClick will change to your example, but I hope this sets you on the right track. For another sample of this, as well as a bit of an explanation for the benefits of handling click logic inside the ViewHolder, check out a blog post that I wrote comparing RecyclerView and ListView (look for the section labeled "More explicit click listeners").