1 /* 2 * Copyright (C) 2020 The Dagger Authors. 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 dagger.hilt.android.scopes; 18 19 import java.lang.annotation.Retention; 20 import java.lang.annotation.RetentionPolicy; 21 import javax.inject.Scope; 22 23 /** 24 * Scope annotation for bindings that should exist for the life of a a single {@link 25 * androidx.lifecycle.ViewModel}. 26 * 27 * <p>Use this scope annotation when you want to define a dependency in the {@link 28 * dagger.hilt.android.components.ViewModelComponent} for which a single instance will be provided 29 * across all other dependencies for a single {@link 30 * dagger.hilt.android.lifecycle.HiltViewModel}-annotated {@code ViewModel}. Other {@code 31 * ViewModel}s that request the scoped dependency will receive a different instance. For sharing the 32 * same instance of a dependency across all {@code ViewModel}s use a scope from one of the parent 33 * components of {@code dagger.hilt.android.components.ViewModelComponent}, such as {@link 34 * javax.inject.Singleton} or {@link dagger.hilt.android.scopes.ActivityRetainedScoped}. 35 * 36 * <p>For example: 37 * 38 * <pre> 39 * @Module 40 * @InstallIn(ViewModelComponent.class) 41 * public final class ViewModelMovieModule { 42 * @Provides 43 * @ViewModelScoped 44 * public static MovieRepository provideRepo(SavedStateHandle handle) { 45 * return new MovieRepository(handle.getString("movie-id")); 46 * } 47 * } 48 * 49 * public final class MovieDetailFetcher { 50 * @Inject MovieDetailFetcher(MovieRepository movieRepo) { 51 * // ... 52 * } 53 * } 54 * 55 * public final class MoviePosterFetcher { 56 * @Inject MoviePosterFetcher(MovieRepository movieRepo) { 57 * // ... 58 * } 59 * } 60 * 61 * @HiltViewModel 62 * public class MovieViewModel extends ViewModel { 63 * @Inject 64 * public MovieViewModel(MovieDetailFetcher detailFetcher, MoviePosterFetcher posterFetcher) { 65 * // Both detailFetcher and posterFetcher will contain the same instance of 66 * // the MovieRepository. 67 * } 68 * } 69 * </pre> 70 * 71 * @see dagger.hilt.android.lifecycle.HiltViewModel 72 * @see dagger.hilt.android.components.ViewModelComponent 73 */ 74 @Scope 75 @Retention(RetentionPolicy.CLASS) 76 public @interface ViewModelScoped {} 77