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.lifecycle; 18 19 import dagger.hilt.GeneratesRootInput; 20 import java.lang.annotation.ElementType; 21 import java.lang.annotation.Retention; 22 import java.lang.annotation.RetentionPolicy; 23 import java.lang.annotation.Target; 24 25 /** 26 * Identifies a {@link androidx.lifecycle.ViewModel} for construction injection. 27 * 28 * <p>The {@code ViewModel} annotated with {@link HiltViewModel} will be available for creation by 29 * the {@link dagger.hilt.android.lifecycle.HiltViewModelFactory} and can be retrieved by default in 30 * an {@code Activity} or {@code Fragment} annotated with {@link 31 * dagger.hilt.android.AndroidEntryPoint}. The {@code HiltViewModel} containing a constructor 32 * annotated with {@link javax.inject.Inject} will have its dependencies defined in the constructor 33 * parameters injected by Dagger's Hilt. 34 * 35 * <p>Example: 36 * 37 * <pre> 38 * @HiltViewModel 39 * public class DonutViewModel extends ViewModel { 40 * @Inject 41 * public DonutViewModel(SavedStateHandle handle, RecipeRepository repository) { 42 * // ... 43 * } 44 * } 45 * </pre> 46 * 47 * <pre> 48 * @AndroidEntryPoint 49 * public class CookingActivity extends AppCompatActivity { 50 * public void onCreate(Bundle savedInstanceState) { 51 * DonutViewModel vm = new ViewModelProvider(this).get(DonutViewModel.class); 52 * } 53 * } 54 * </pre> 55 * 56 * <p>Exactly one constructor in the {@code ViewModel} must be annotated with {@code Inject}. 57 * 58 * <p>Only dependencies available in the {@link dagger.hilt.android.components.ViewModelComponent} 59 * can be injected into the {@code ViewModel}. 60 * 61 * <p> 62 * 63 * @see dagger.hilt.android.components.ViewModelComponent 64 */ 65 @Target(ElementType.TYPE) 66 @Retention(RetentionPolicy.CLASS) 67 @GeneratesRootInput 68 public @interface HiltViewModel {} 69