1 /* 2 * Copyright (C) 2007 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; 18 19 import static java.lang.annotation.ElementType.METHOD; 20 import static java.lang.annotation.RetentionPolicy.RUNTIME; 21 22 import java.lang.annotation.Documented; 23 import java.lang.annotation.Retention; 24 import java.lang.annotation.Target; 25 26 /** 27 * Annotates methods of a {@linkplain Module module} to create a provider method binding. The 28 * method's return type is bound to its returned value. The {@linkplain Component component} 29 * implementation will pass dependencies to the method as parameters. 30 * 31 * <h3>Nullability</h3> 32 * 33 * <p>Dagger forbids injecting {@code null} by default. Component implemenations that invoke 34 * {@code @Provides} methods that return {@code null} will throw a {@link NullPointerException} 35 * immediately thereafter. {@code @Provides} methods may opt into allowing {@code null} by 36 * annotating the method with any {@code @Nullable} annotation like 37 * {@code javax.annotation.Nullable} or {@code android.support.annotation.Nullable}. 38 * 39 * <p>If a {@code @Provides} method is marked {@code @Nullable}, Dagger will <em>only</em> 40 * allow injection into sites that are marked {@code @Nullable} as well. A component that 41 * attempts to pair a {@code @Nullable} provision with a non-{@code @Nullable} injection site 42 * will fail to compile. 43 */ 44 @Documented @Target(METHOD) @Retention(RUNTIME) 45 public @interface Provides { 46 } 47