| /* |
| * Copyright (C) 2020 The Dagger Authors. |
| * |
| * 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 dagger.hilt.android.migration; |
| |
| import java.lang.annotation.ElementType; |
| import java.lang.annotation.Target; |
| |
| /** |
| * When placed on an {@link dagger.hilt.android.AndroidEntryPoint}-annotated activity / fragment / |
| * view / etc, allows injection to occur optionally based on whether or not the application is using |
| * Hilt. |
| * |
| * <p>When using this annotation, you can use {@link OptionalInjectCheck#wasInjectedByHilt} to check |
| * at runtime if the annotated class was injected by Hilt. Additionally, this annotation will also |
| * cause a method, {@code wasInjectedByHilt} to be generated in the Hilt base class as well, that |
| * behaves the same as {@link OptionalInjectCheck#wasInjectedByHilt}. The method is available to |
| * users that extend the Hilt base class directly and don't use the Gradle plugin. |
| * |
| * <p>Example usage: |
| * |
| * <pre><code> |
| * {@literal @}OptionalInject |
| * {@literal @}AndroidEntryPoint |
| * public final class MyFragment extends Fragment { |
| * |
| * {@literal @}Inject Foo foo; |
| * |
| * {@literal @}Override |
| * public void onAttach(Activity activity) { |
| * // Injection will happen here, but only if the Activity and the Application are also |
| * // AndroidEntryPoints and were injected by Hilt. |
| * super.onAttach(activity); |
| * if (!OptionalInjectCheck.wasInjectedByHilt(this)) { |
| * // Get Dagger components the previous way and inject. |
| * } |
| * } |
| * } |
| * </code></pre> |
| * |
| * <p>This is useful for libraries that have to support Hilt users as well as non-Hilt users. |
| * Injection will happen if the parent type (e.g. the activity of a fragment) is an {@link |
| * dagger.hilt.android.AndroidEntryPoint} annotated class and if that parent was also injected via |
| * Hilt. |
| * |
| * @see OptionalInjectCheck |
| * @see <a href="https://dagger.dev/hilt/optional-inject">Optional injection</a> |
| */ |
| @Target(ElementType.TYPE) |
| public @interface OptionalInject {} |