1/* 2 * Copyright 2018 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 17package com.example.androidx.car; 18 19import android.app.Activity; 20import android.content.Context; 21import android.os.Bundle; 22import android.os.Handler; 23 24import androidx.car.widget.ListItem; 25import androidx.car.widget.ListItemAdapter; 26import androidx.car.widget.ListItemProvider; 27import androidx.car.widget.PagedListView; 28import androidx.car.widget.TextListItem; 29 30/** 31 * A demo activity that will display a {@link PagedListView} that has less items than can fit 32 * on the screen and will vertically center these. This activity will continually add more 33 * items as time goes on. 34 */ 35public class VerticallyCenteredListDemo extends Activity { 36 private static final int ADD_ITEM_DELAY_MS = 1000; 37 private static final int MAX_NUM_OF_ITEMS_TO_ADD = 10; 38 39 private int mNumOfItemsAdded; 40 41 @Override 42 protected void onCreate(Bundle savedInstanceState) { 43 super.onCreate(savedInstanceState); 44 setContentView(R.layout.vertically_centered_paged_list_view); 45 46 PagedListView list = findViewById(R.id.paged_list_view); 47 48 CustomListProvider provider = new CustomListProvider(/* context= */ this); 49 ListItemAdapter adapter = new ListItemAdapter(/* context= */ this, provider); 50 51 list.setAdapter(adapter); 52 53 Handler handler = new Handler(); 54 55 // Continually add items to the list until MAX_NUM_OF_ITEMS_TO_ADD is reached. 56 handler.postDelayed(new Runnable() { 57 @Override 58 public void run() { 59 if (++mNumOfItemsAdded >= MAX_NUM_OF_ITEMS_TO_ADD) { 60 return; 61 } 62 63 provider.addListItem(); 64 adapter.notifyDataSetChanged(); 65 handler.postDelayed(this, ADD_ITEM_DELAY_MS); 66 } 67 }, ADD_ITEM_DELAY_MS); 68 } 69 70 /** 71 * A custom {@link ListItemProvider} that allows additional {@link ListItem}s to be added to it. 72 */ 73 private static class CustomListProvider extends ListItemProvider { 74 private static final int INITIAL_NUM_OF_ITEMS = 3; 75 76 private int mNumOfItems = INITIAL_NUM_OF_ITEMS; 77 private final Context mContext; 78 79 CustomListProvider(Context context) { 80 mContext = context; 81 } 82 83 public void addListItem() { 84 mNumOfItems++; 85 } 86 87 public ListItem get(int position) { 88 TextListItem item = new TextListItem(mContext); 89 item.setTitle("Item " + position); 90 return item; 91 } 92 93 public int size() { 94 return mNumOfItems; 95 } 96 97 } 98} 99