1 /* 2 * Copyright (C) 2014 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 package com.example.android.recyclerview; 18 19 import android.os.Bundle; 20 import android.support.v4.app.Fragment; 21 import android.support.v7.widget.GridLayoutManager; 22 import android.support.v7.widget.LinearLayoutManager; 23 import android.support.v7.widget.RecyclerView; 24 import android.view.LayoutInflater; 25 import android.view.View; 26 import android.view.ViewGroup; 27 import android.widget.RadioButton; 28 29 /** 30 * Demonstrates the use of {@link RecyclerView} with a {@link LinearLayoutManager} and a 31 * {@link GridLayoutManager}. 32 */ 33 public class RecyclerViewFragment extends Fragment { 34 35 private static final String TAG = "RecyclerViewFragment"; 36 private static final String KEY_LAYOUT_MANAGER = "layoutManager"; 37 private static final int SPAN_COUNT = 2; 38 private static final int DATASET_COUNT = 60; 39 40 private enum LayoutManagerType { 41 GRID_LAYOUT_MANAGER, 42 LINEAR_LAYOUT_MANAGER 43 } 44 45 protected LayoutManagerType mCurrentLayoutManagerType; 46 47 protected RadioButton mLinearLayoutRadioButton; 48 protected RadioButton mGridLayoutRadioButton; 49 50 protected RecyclerView mRecyclerView; 51 protected CustomAdapter mAdapter; 52 protected RecyclerView.LayoutManager mLayoutManager; 53 protected String[] mDataset; 54 55 @Override onCreate(Bundle savedInstanceState)56 public void onCreate(Bundle savedInstanceState) { 57 super.onCreate(savedInstanceState); 58 59 // Initialize dataset, this data would usually come from a local content provider or 60 // remote server. 61 initDataset(); 62 } 63 64 @Override onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)65 public View onCreateView(LayoutInflater inflater, ViewGroup container, 66 Bundle savedInstanceState) { 67 View rootView = inflater.inflate(R.layout.recycler_view_frag, container, false); 68 rootView.setTag(TAG); 69 70 // BEGIN_INCLUDE(initializeRecyclerView) 71 mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView); 72 73 // LinearLayoutManager is used here, this will layout the elements in a similar fashion 74 // to the way ListView would layout elements. The RecyclerView.LayoutManager defines how 75 // elements are laid out. 76 mLayoutManager = new LinearLayoutManager(getActivity()); 77 78 mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER; 79 80 if (savedInstanceState != null) { 81 // Restore saved layout manager type. 82 mCurrentLayoutManagerType = (LayoutManagerType) savedInstanceState 83 .getSerializable(KEY_LAYOUT_MANAGER); 84 } 85 setRecyclerViewLayoutManager(mCurrentLayoutManagerType); 86 87 mAdapter = new CustomAdapter(mDataset); 88 // Set CustomAdapter as the adapter for RecyclerView. 89 mRecyclerView.setAdapter(mAdapter); 90 // END_INCLUDE(initializeRecyclerView) 91 92 mLinearLayoutRadioButton = (RadioButton) rootView.findViewById(R.id.linear_layout_rb); 93 mLinearLayoutRadioButton.setOnClickListener(new View.OnClickListener() { 94 @Override 95 public void onClick(View v) { 96 setRecyclerViewLayoutManager(LayoutManagerType.LINEAR_LAYOUT_MANAGER); 97 } 98 }); 99 100 mGridLayoutRadioButton = (RadioButton) rootView.findViewById(R.id.grid_layout_rb); 101 mGridLayoutRadioButton.setOnClickListener(new View.OnClickListener() { 102 @Override 103 public void onClick(View v) { 104 setRecyclerViewLayoutManager(LayoutManagerType.GRID_LAYOUT_MANAGER); 105 } 106 }); 107 108 return rootView; 109 } 110 111 /** 112 * Set RecyclerView's LayoutManager to the one given. 113 * 114 * @param layoutManagerType Type of layout manager to switch to. 115 */ setRecyclerViewLayoutManager(LayoutManagerType layoutManagerType)116 public void setRecyclerViewLayoutManager(LayoutManagerType layoutManagerType) { 117 int scrollPosition = 0; 118 119 // If a layout manager has already been set, get current scroll position. 120 if (mRecyclerView.getLayoutManager() != null) { 121 scrollPosition = ((LinearLayoutManager) mRecyclerView.getLayoutManager()) 122 .findFirstCompletelyVisibleItemPosition(); 123 } 124 125 switch (layoutManagerType) { 126 case GRID_LAYOUT_MANAGER: 127 mLayoutManager = new GridLayoutManager(getActivity(), SPAN_COUNT); 128 mCurrentLayoutManagerType = LayoutManagerType.GRID_LAYOUT_MANAGER; 129 break; 130 case LINEAR_LAYOUT_MANAGER: 131 mLayoutManager = new LinearLayoutManager(getActivity()); 132 mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER; 133 break; 134 default: 135 mLayoutManager = new LinearLayoutManager(getActivity()); 136 mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER; 137 } 138 139 mRecyclerView.setLayoutManager(mLayoutManager); 140 mRecyclerView.scrollToPosition(scrollPosition); 141 } 142 143 @Override onSaveInstanceState(Bundle savedInstanceState)144 public void onSaveInstanceState(Bundle savedInstanceState) { 145 // Save currently selected layout manager. 146 savedInstanceState.putSerializable(KEY_LAYOUT_MANAGER, mCurrentLayoutManagerType); 147 super.onSaveInstanceState(savedInstanceState); 148 } 149 150 /** 151 * Generates Strings for RecyclerView's adapter. This data would usually come 152 * from a local content provider or remote server. 153 */ initDataset()154 private void initDataset() { 155 mDataset = new String[DATASET_COUNT]; 156 for (int i = 0; i < DATASET_COUNT; i++) { 157 mDataset[i] = "This is element #" + i; 158 } 159 } 160 } 161