1/*
2 * Copyright (C) 2013 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 */
16package androidx.annotation;
17
18import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
19import static java.lang.annotation.ElementType.FIELD;
20import static java.lang.annotation.ElementType.LOCAL_VARIABLE;
21import static java.lang.annotation.ElementType.METHOD;
22import static java.lang.annotation.ElementType.PACKAGE;
23import static java.lang.annotation.ElementType.PARAMETER;
24import static java.lang.annotation.RetentionPolicy.CLASS;
25
26import java.lang.annotation.Documented;
27import java.lang.annotation.Retention;
28import java.lang.annotation.Target;
29
30/**
31 * Denotes that a parameter, field or method return value can be null.
32 * <p>
33 * When decorating a method call parameter, this denotes that the parameter can
34 * legitimately be null and the method will gracefully deal with it. Typically
35 * used on optional parameters.
36 * <p>
37 * When decorating a method, this denotes the method might legitimately return
38 * null.
39 * <p>
40 * This is a marker annotation and it has no specific attributes.
41 */
42@Documented
43@Retention(CLASS)
44@Target({METHOD, PARAMETER, FIELD, LOCAL_VARIABLE, ANNOTATION_TYPE, PACKAGE})
45public @interface Nullable {
46}
47