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      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
     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
     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      */
    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
    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      */
    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