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      1 /*
      2  * Copyright (C) 2015 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 
     18 package com.example.android.supportv7.widget;
     19 
     20 import android.app.Activity;
     21 import android.content.Context;
     22 import android.os.Bundle;
     23 import android.support.v7.util.AsyncListUtil;
     24 import android.support.v7.widget.LinearLayoutManager;
     25 import android.support.v7.widget.RecyclerView;
     26 import android.view.Menu;
     27 import android.view.MenuItem;
     28 import android.view.ViewGroup;
     29 import android.widget.TextView;
     30 
     31 import com.example.android.supportv7.Cheeses;
     32 
     33 /**
     34  * A sample Activity to demonstrate capabilities of {@link AsyncListUtil}.
     35  */
     36 public class AsyncListUtilActivity extends Activity {
     37 
     38     private static final String TAG = "AsyncListUtilActivity";
     39 
     40     private RecyclerView mRecyclerView;
     41 
     42     private LinearLayoutManager mLinearLayoutManager;
     43 
     44     @Override
     45     protected void onCreate(Bundle savedInstanceState) {
     46         super.onCreate(savedInstanceState);
     47 
     48         mRecyclerView = new RecyclerView(this);
     49         mLinearLayoutManager = new LinearLayoutManager(this);
     50         mRecyclerView.setLayoutManager(mLinearLayoutManager);
     51         mRecyclerView.setHasFixedSize(true);
     52         final ViewGroup.LayoutParams layoutParams = new ViewGroup.LayoutParams(
     53                 ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT);
     54         mRecyclerView.setLayoutParams(layoutParams);
     55         mRecyclerView.setAdapter(new AsyncAdapter());
     56         setContentView(mRecyclerView);
     57     }
     58 
     59     @Override
     60     public boolean onCreateOptionsMenu(Menu menu) {
     61         super.onCreateOptionsMenu(menu);
     62         menu.add("Layout").setShowAsAction(MenuItem.SHOW_AS_ACTION_IF_ROOM);
     63         return true;
     64     }
     65 
     66     @Override
     67     public boolean onOptionsItemSelected(MenuItem item) {
     68         mRecyclerView.requestLayout();
     69         return super.onOptionsItemSelected(item);
     70     }
     71 
     72     private static class TextViewHolder extends RecyclerView.ViewHolder {
     73         TextView textView;
     74         public TextViewHolder(Context context) {
     75             super(new TextView(context));
     76             textView = (TextView) itemView;
     77         }
     78     }
     79 
     80     private class AsyncAdapter extends RecyclerView.Adapter<TextViewHolder> {
     81 
     82         private AsyncListUtil<String> mAsyncListUtil;
     83 
     84         AsyncAdapter() {
     85             mAsyncListUtil = new AsyncStringListUtil();
     86         }
     87 
     88         @Override
     89         public TextViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
     90             return new TextViewHolder(parent.getContext());
     91         }
     92 
     93         @Override
     94         public void onBindViewHolder(TextViewHolder holder, int position) {
     95             final String itemString = mAsyncListUtil.getItem(position);
     96             if (itemString == null) {
     97                 holder.textView.setText("loading...");
     98             } else {
     99                 holder.textView.setText(itemString);
    100             }
    101         }
    102 
    103         @Override
    104         public int getItemCount() {
    105             return mAsyncListUtil.getItemCount();
    106         }
    107     }
    108 
    109     private class AsyncStringListUtil extends AsyncListUtil<String> {
    110 
    111         private static final int TILE_SIZE = 5;
    112 
    113         private static final long DELAY_MS = 500;
    114 
    115         public AsyncStringListUtil() {
    116             super(String.class, TILE_SIZE,
    117                     new AsyncListUtil.DataCallback<String>() {
    118                         @Override
    119                         public int refreshData() {
    120                             return Cheeses.sCheeseStrings.length;
    121                         }
    122 
    123                         @Override
    124                         public void fillData(String[] data, int startPosition, int itemCount) {
    125                             sleep();
    126                             for (int i = 0; i < itemCount; i++) {
    127                                 data[i] = Cheeses.sCheeseStrings[startPosition + i];
    128                             }
    129                         }
    130 
    131                         private void sleep() {
    132                             try {
    133                                 Thread.sleep(DELAY_MS);
    134                             } catch (InterruptedException e) {
    135                                 e.printStackTrace();
    136                             }
    137                         }
    138                     },
    139                     new AsyncListUtil.ViewCallback() {
    140                         @Override
    141                         public void getItemRangeInto(int[] outRange) {
    142                             outRange[0] = mLinearLayoutManager.findFirstVisibleItemPosition();
    143                             outRange[1] = mLinearLayoutManager.findLastVisibleItemPosition();
    144                         }
    145 
    146                         @Override
    147                         public void onDataRefresh() {
    148                             mRecyclerView.getAdapter().notifyDataSetChanged();
    149                         }
    150 
    151                         @Override
    152                         public void onItemLoaded(int position) {
    153                             mRecyclerView.getAdapter().notifyItemChanged(position);
    154                         }
    155                     });
    156 
    157             mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
    158                 @Override
    159                 public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
    160                     onRangeChanged();
    161                 }
    162             });
    163         }
    164     }
    165 }
    166