Java tutorial
/*** Copyright (c) 2014 CommonsWare, LLC 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. Covered in detail in the book _The Busy Coder's Guide to Android Development_ https://commonsware.com/Android */ package com.commonsware.android.fts; import android.app.Activity; import android.content.Context; import android.database.Cursor; import android.os.Bundle; import android.support.v4.app.Fragment; import android.util.Log; import org.greenrobot.eventbus.EventBus; import org.greenrobot.eventbus.Subscribe; import org.greenrobot.eventbus.ThreadMode; import retrofit2.Retrofit; import retrofit2.converter.gson.GsonConverterFactory; public class ModelFragment extends Fragment { private Context app = null; @Override public void onCreate(Bundle state) { super.onCreate(state); setRetainInstance(true); } @Override public void onAttach(Activity host) { super.onAttach(host); EventBus.getDefault().register(this); if (app == null) { app = host.getApplicationContext(); new FetchQuestionsThread().start(); } } @Override public void onDetach() { EventBus.getDefault().unregister(this); super.onDetach(); } @Subscribe(threadMode = ThreadMode.BACKGROUND) public void onSearchRequested(SearchRequestedEvent event) { try { Cursor results = DatabaseHelper.getInstance(app).loadQuestions(app, event.match); EventBus.getDefault().postSticky(new ModelLoadedEvent(results)); } catch (Exception e) { Log.e(getClass().getSimpleName(), "Exception searching database", e); } } class FetchQuestionsThread extends Thread { @Override public void run() { Retrofit retrofit = new Retrofit.Builder().baseUrl("https://api.stackexchange.com") .addConverterFactory(GsonConverterFactory.create()).build(); StackOverflowInterface so = retrofit.create(StackOverflowInterface.class); try { SOQuestions questions = so.questions("android").execute().body(); DatabaseHelper.getInstance(app).insertQuestions(app, questions.items); } catch (Exception e) { Log.e(getClass().getSimpleName(), "Exception populating database", e); } try { Cursor results = DatabaseHelper.getInstance(app).loadQuestions(app, null); EventBus.getDefault().postSticky(new ModelLoadedEvent(results)); } catch (Exception e) { Log.e(getClass().getSimpleName(), "Exception populating database", e); } } } }