| /* |
| * Copyright 2015 Google Inc. All rights reserved. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.example.android.xyztouristattractions.ui; |
| |
| import android.content.Context; |
| import android.util.AttributeSet; |
| import android.view.View; |
| |
| import androidx.recyclerview.widget.RecyclerView; |
| |
| /** |
| * Simple RecyclerView subclass that supports providing an empty view (which |
| * is displayed when the adapter has no data and hidden otherwise). |
| */ |
| public class AttractionsRecyclerView extends RecyclerView { |
| private View mEmptyView; |
| |
| private AdapterDataObserver mDataObserver = new AdapterDataObserver() { |
| @Override |
| public void onChanged() { |
| super.onChanged(); |
| updateEmptyView(); |
| } |
| }; |
| |
| public AttractionsRecyclerView(Context context) { |
| super(context); |
| } |
| |
| public AttractionsRecyclerView(Context context, AttributeSet attrs) { |
| super(context, attrs); |
| } |
| |
| public AttractionsRecyclerView(Context context, AttributeSet attrs, int defStyle) { |
| super(context, attrs, defStyle); |
| } |
| |
| /** |
| * Designate a view as the empty view. When the backing adapter has no |
| * data this view will be made visible and the recycler view hidden. |
| * |
| */ |
| public void setEmptyView(View emptyView) { |
| mEmptyView = emptyView; |
| } |
| |
| @Override |
| public void setAdapter(RecyclerView.Adapter adapter) { |
| if (getAdapter() != null) { |
| getAdapter().unregisterAdapterDataObserver(mDataObserver); |
| } |
| if (adapter != null) { |
| adapter.registerAdapterDataObserver(mDataObserver); |
| } |
| super.setAdapter(adapter); |
| updateEmptyView(); |
| } |
| |
| private void updateEmptyView() { |
| if (mEmptyView != null && getAdapter() != null) { |
| boolean showEmptyView = getAdapter().getItemCount() == 0; |
| mEmptyView.setVisibility(showEmptyView ? VISIBLE : GONE); |
| setVisibility(showEmptyView ? GONE : VISIBLE); |
| } |
| } |
| } |