1 /* 2 * Copyright (C) 2011 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 17 package com.android.annotations; 18 19 import static java.lang.annotation.ElementType.FIELD; 20 import static java.lang.annotation.ElementType.LOCAL_VARIABLE; 21 import static java.lang.annotation.ElementType.METHOD; 22 import static java.lang.annotation.ElementType.PARAMETER; 23 24 import java.lang.annotation.Documented; 25 import java.lang.annotation.Retention; 26 import java.lang.annotation.RetentionPolicy; 27 import java.lang.annotation.Target; 28 29 /** 30 * Denotes that a parameter, field or method return value can be null. 31 * <b>Note</b>: this is the default assumption for most Java APIs and the 32 * default assumption made by most static code checking tools, so usually you 33 * don't need to use this annotation; its primary use is to override a default 34 * wider annotation like {@link NonNullByDefault}. 35 * <p/> 36 * When decorating a method call parameter, this denotes the parameter can 37 * legitimately be null and the method will gracefully deal with it. Typically 38 * used on optional parameters. 39 * <p/> 40 * When decorating a method, this denotes the method might legitimately return 41 * null. 42 * <p/> 43 * This is a marker annotation and it has no specific attributes. 44 */ 45 @Documented 46 @Retention(RetentionPolicy.CLASS) 47 @Target({METHOD, PARAMETER, LOCAL_VARIABLE, FIELD}) 48 public @interface Nullable { 49 } 50