Java tutorial
/* * Copyright 2014 Realm Inc. * * 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.baidao.realm_threadexample; import android.os.Bundle; import android.os.SystemClock; import android.support.v4.app.Fragment; import android.view.LayoutInflater; import android.view.Menu; import android.view.MenuInflater; import android.view.MenuItem; import android.view.View; import android.view.ViewGroup; import com.baidao.realm_threadexample.model.Dot; import com.baidao.realm_threadexample.widget.DotsView; import java.util.Random; import io.realm.Realm; import io.realm.RealmChangeListener; /** * This fragment demonstrates how Realm can interact with a background thread. */ public class ThreadFragment extends Fragment { private Realm realm; private Random random = new Random(); private Thread backgroundThread; private DotsView dotsView; // Realm change listener that refreshes the UI when there is changes to Realm. private RealmChangeListener<Realm> realmListener = new RealmChangeListener<Realm>() { @Override public void onChange(Realm realm) { dotsView.invalidate(); } }; @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setHasOptionsMenu(true); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { View rootView = inflater.inflate(R.layout.fragment_thread, container, false); dotsView = (DotsView) rootView.findViewById(R.id.dots); return rootView; } @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { super.onCreateOptionsMenu(menu, inflater); inflater.inflate(R.menu.menu_backgroundthread, menu); } @Override public boolean onOptionsItemSelected(MenuItem item) { switch (item.getItemId()) { case R.id.action_add_dot: // Add blue dot from the UI thread realm.executeTransaction(new Realm.Transaction() { @Override public void execute(Realm realm) { Dot dot = realm.createObject(Dot.class); dot.setX(random.nextInt(100)); dot.setY(random.nextInt(100)); dot.setColor(getResources().getColor(R.color.realm_blue)); } }); return true; case R.id.action_clear: realm.executeTransaction(new Realm.Transaction() { @Override public void execute(Realm realm) { realm.delete(Dot.class); } }); return true; default: return super.onOptionsItemSelected(item); } } @Override public void onStart() { super.onStart(); // Create Realm instance for the UI thread realm = Realm.getDefaultInstance(); // Create a RealmQuery on the UI thread and send the results to the custom view. The // RealmResults will automatically be updated whenever the Realm data is changed. // We still need to invalidate the UI to show the changes however. See the RealmChangeListener. // // Note that the query gets updated by rerunning it on the thread it was // created. This can negatively effect frame rates if it is a complicated query or a very // large data set. dotsView.setRealmResults(realm.where(Dot.class).findAll()); } @Override public void onResume() { super.onResume(); // Enable UI refresh while the fragment is active. realm.addChangeListener(realmListener); // Create background thread that add a new dot every 0.5 second. backgroundThread = new Thread() { @Override public void run() { // Realm instances cannot be shared between threads, so we need to create a new // instance on the background thread. final int redColor = getResources().getColor(R.color.realm_red); final Realm backgroundThreadRealm = Realm.getDefaultInstance(); while (!backgroundThread.isInterrupted()) { backgroundThreadRealm.executeTransaction(new Realm.Transaction() { @Override public void execute(Realm realm) { // Add red dot from the background thread Dot dot = backgroundThreadRealm.createObject(Dot.class); dot.setX(random.nextInt(100)); dot.setY(random.nextInt(100)); dot.setColor(redColor); } }); // Wait 0.5 sec. before adding the next dot. SystemClock.sleep(500); } // Also close Realm instances used in background threads. backgroundThreadRealm.close(); } }; backgroundThread.start(); } @Override public void onPause() { super.onPause(); // Disable UI refresh while the fragment is no longer active. realm.removeChangeListener(realmListener); backgroundThread.interrupt(); } @Override public void onStop() { super.onStop(); // Remember to close the Realm instance when done with it. realm.close(); } }