content: package com.nbsp.materialfilepicker.widget;
  
  import android.content.Context;
  import android.support.annotation.NonNull;
  import android.support.annotation.Nullable;
  import android.support.v7.widget.RecyclerView;
  import android.util.AttributeSet;
  import android.view.View;
  
  public class EmptyRecyclerView extends RecyclerView {
      @Nullable
      View mEmptyView;
  
      public EmptyRecyclerView(Context context) {
          super(context);
      }
  
      public EmptyRecyclerView(Context context, AttributeSet attrs) {
          super(context, attrs);
      }
  
      public EmptyRecyclerView(Context context, AttributeSet attrs, int defStyle) {
          super(context, attrs, defStyle);
      }
  
      void checkIfEmpty() {
          if (mEmptyView != null) {
              mEmptyView.setVisibility(getAdapter().getItemCount() > 0 ? GONE : VISIBLE);
          }
      }
  
      final
      @NonNull
      AdapterDataObserver observer = new AdapterDataObserver() {
          @Override
          public void onChanged() {
              super.onChanged();
              checkIfEmpty();
          }
      };
  
      @Override
      public void setAdapter(@Nullable Adapter adapter) {
          final Adapter oldAdapter = getAdapter();
          if (oldAdapter != null) {
              oldAdapter.unregisterAdapterDataObserver(observer);
          }
          super.setAdapter(adapter);
          if (adapter != null) {
              adapter.registerAdapterDataObserver(observer);
          }
      }
  
      public void setEmptyView(@Nullable View mEmptyView) {
          this.mEmptyView = mEmptyView;
          checkIfEmpty();
      }
  }
  