1 /* 2 * Copyright 2018 The Android Open Source Project 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 androidx.annotation; 17 18 import static java.lang.annotation.ElementType.CONSTRUCTOR; 19 import static java.lang.annotation.ElementType.FIELD; 20 import static java.lang.annotation.ElementType.METHOD; 21 import static java.lang.annotation.ElementType.TYPE; 22 import static java.lang.annotation.RetentionPolicy.SOURCE; 23 24 import java.lang.annotation.Retention; 25 import java.lang.annotation.Target; 26 27 /** 28 * Denotes that the annotated element requires one or more features. This is used to auto-generate 29 * documentation, and more importantly: to ensure correct usage in application code, where lint and 30 * Android Studio can check that calls marked with this annotation is surrounded by has-feature 31 * calls, referenced via the {@link RequiresFeature#enforcement()} attribute. 32 */ 33 @Retention(SOURCE) 34 @Target({TYPE, FIELD, METHOD, CONSTRUCTOR}) 35 public @interface RequiresFeature { 36 /** 37 * The name of the feature that is required. 38 */ name()39 String name(); 40 41 /** 42 * Defines the name of the method that should be called to check whether the feature is 43 * available, using the same signature format as javadoc. 44 * The feature checking method can have multiple parameters, but the feature name parameter must 45 * be of type String and must also be the first String-type parameter. 46 */ enforcement()47 String enforcement(); 48 } 49