1 /* 2 * Copyright (C) 2014 Google Inc. 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 dagger.internal; 17 18 import dagger.MembersInjector; 19 import javax.inject.Inject; 20 21 /** 22 * Basic {@link MembersInjector} implementations used by the framework. 23 * 24 * @author Gregory Kick 25 * @since 2.0 26 */ 27 public final class MembersInjectors { 28 /** 29 * Returns a {@link MembersInjector} implementation that injects no members 30 * 31 * <p>Note that there is no verification that the type being injected does not have {@link Inject} 32 * members, so care should be taken to ensure appropriate use. 33 */ 34 @SuppressWarnings("unchecked") 35 public static <T> MembersInjector<T> noOp() { 36 return (MembersInjector<T>) NoOpMembersInjector.INSTANCE; 37 } 38 39 private static enum NoOpMembersInjector implements MembersInjector<Object> { 40 INSTANCE; 41 42 @Override public void injectMembers(Object instance) { 43 if (instance == null) { 44 throw new NullPointerException(); 45 } 46 } 47 } 48 49 /** 50 * Returns a {@link MembersInjector} that delegates to the {@link MembersInjector} of its 51 * supertype. This is useful for cases where a type is known not to have its own {@link Inject} 52 * members, but must still inject members on its supertype(s). 53 * 54 * <p>Note that there is no verification that the type being injected does not have {@link Inject} 55 * members, so care should be taken to ensure appropriate use. 56 */ 57 @SuppressWarnings("unchecked") 58 public static <T> MembersInjector<T> delegatingTo(MembersInjector<? super T> delegate) { 59 return (MembersInjector<T>) delegate; 60 } 61 62 private MembersInjectors() {} 63 } 64
