Java tutorial
/* * Copyright (C) 2014 The Android Open Source Project * * 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.lozasolutions.spaces4all.fragments; import android.os.Bundle; import android.support.v4.app.Fragment; import android.support.v7.widget.GridLayoutManager; import android.support.v7.widget.LinearLayoutManager; import android.support.v7.widget.RecyclerView; import android.view.LayoutInflater; import android.view.View; import android.view.ViewGroup; import android.widget.RadioButton; import com.lozasolutions.spaces4all.R; import com.lozasolutions.spaces4all.adapter.PoiAdapter; /** * Demonstrates the use of {@link RecyclerView} with a {@link LinearLayoutManager} and a * {@link GridLayoutManager}. */ public class ListPoi extends Fragment { private static final String TAG = "ListPoi"; private static final String KEY_LAYOUT_MANAGER = "layoutManager"; private static final int SPAN_COUNT = 2; private static final int DATASET_COUNT = 60; private enum LayoutManagerType { GRID_LAYOUT_MANAGER, LINEAR_LAYOUT_MANAGER } protected LayoutManagerType mCurrentLayoutManagerType; protected RadioButton mLinearLayoutRadioButton; protected RadioButton mGridLayoutRadioButton; protected RecyclerView mRecyclerView; protected PoiAdapter mAdapter; protected RecyclerView.LayoutManager mLayoutManager; protected String[] mDataset; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Initialize dataset, this data would usually come from a local content provider or // remote server. initDataset(); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.list_poi_fragment, container, false); rootView.setTag(TAG); // BEGIN_INCLUDE(initializeRecyclerView) mRecyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView); // LinearLayoutManager is used here, this will layout the elements in a similar fashion // to the way ListView would layout elements. The RecyclerView.LayoutManager defines how // elements are laid out. mLayoutManager = new LinearLayoutManager(getActivity()); mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER; if (savedInstanceState != null) { // Restore saved layout manager type. mCurrentLayoutManagerType = (LayoutManagerType) savedInstanceState.getSerializable(KEY_LAYOUT_MANAGER); } setRecyclerViewLayoutManager(mCurrentLayoutManagerType); mAdapter = new PoiAdapter(mDataset); // Set PoiAdapter as the adapter for RecyclerView. mRecyclerView.setAdapter(mAdapter); // END_INCLUDE(initializeRecyclerView) return rootView; } /** * Set RecyclerView's LayoutManager to the one given. * * @param layoutManagerType Type of layout manager to switch to. */ public void setRecyclerViewLayoutManager(LayoutManagerType layoutManagerType) { int scrollPosition = 0; // If a layout manager has already been set, get current scroll position. if (mRecyclerView.getLayoutManager() != null) { scrollPosition = ((LinearLayoutManager) mRecyclerView.getLayoutManager()) .findFirstCompletelyVisibleItemPosition(); } switch (layoutManagerType) { case GRID_LAYOUT_MANAGER: mLayoutManager = new GridLayoutManager(getActivity(), SPAN_COUNT); mCurrentLayoutManagerType = LayoutManagerType.GRID_LAYOUT_MANAGER; break; case LINEAR_LAYOUT_MANAGER: mLayoutManager = new LinearLayoutManager(getActivity()); mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER; break; default: mLayoutManager = new LinearLayoutManager(getActivity()); mCurrentLayoutManagerType = LayoutManagerType.LINEAR_LAYOUT_MANAGER; } mRecyclerView.setLayoutManager(mLayoutManager); mRecyclerView.scrollToPosition(scrollPosition); } @Override public void onSaveInstanceState(Bundle savedInstanceState) { // Save currently selected layout manager. savedInstanceState.putSerializable(KEY_LAYOUT_MANAGER, mCurrentLayoutManagerType); super.onSaveInstanceState(savedInstanceState); } /** * Generates Strings for RecyclerView's adapter. This data would usually come * from a local content provider or remote server. */ private void initDataset() { mDataset = new String[DATASET_COUNT]; for (int i = 0; i < DATASET_COUNT; i++) { mDataset[i] = "This is element #" + i; } } }