1 /* 2 * Copyright (C) 2018 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 package com.android.launcher3.util; 17 18 import android.content.Context; 19 import android.os.Looper; 20 21 import com.android.launcher3.MainThreadExecutor; 22 23 import java.util.concurrent.ExecutionException; 24 25 import androidx.annotation.VisibleForTesting; 26 27 /** 28 * Utility class for defining singletons which are initiated on main thread. 29 */ 30 public class MainThreadInitializedObject<T> { 31 32 private final ObjectProvider<T> mProvider; 33 private T mValue; 34 MainThreadInitializedObject(ObjectProvider<T> provider)35 public MainThreadInitializedObject(ObjectProvider<T> provider) { 36 mProvider = provider; 37 } 38 get(Context context)39 public T get(Context context) { 40 if (mValue == null) { 41 if (Looper.myLooper() == Looper.getMainLooper()) { 42 mValue = mProvider.get(context.getApplicationContext()); 43 } else { 44 try { 45 return new MainThreadExecutor().submit(() -> get(context)).get(); 46 } catch (InterruptedException|ExecutionException e) { 47 throw new RuntimeException(e); 48 } 49 } 50 } 51 return mValue; 52 } 53 getNoCreate()54 public T getNoCreate() { 55 return mValue; 56 } 57 58 @VisibleForTesting initializeForTesting(T value)59 public void initializeForTesting(T value) { 60 mValue = value; 61 } 62 63 public interface ObjectProvider<T> { 64 get(Context context)65 T get(Context context); 66 } 67 } 68