Experimental.java
/*
* Copyright 2019 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package androidx.annotation.experimental;
import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
import static java.lang.annotation.RetentionPolicy.CLASS;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
/**
* Denotes that the annotated element is a marker of an experimental API.
*
* Any declaration annotated with this marker is considered part of an unstable API surface and its
* call sites should accept the experimental aspect of it either by using {@link UseExperimental},
* or by being annotated with that marker themselves, effectively causing further propagation of
* that experimental aspect.
*
* Example:
* <pre><code>
* // Library code
* @Retention(CLASS)
* @Target({TYPE, METHOD, CONSTRUCTOR, FIELD, PACKAGE})
* @Experimental(level = Level.ERROR)
* public @interface ExperimentalDateTime {}
*
* @ExperimentalDateTime
* public class DateProvider {
* // ...
* }
* </code></pre>
*
* <pre><code>
* // Client code
* int getYear() {
* DateProvider provider; // Error: DateProvider is experimental
* // ...
* }
*
* @ExperimentalDateTime
* Date getDate() {
* DateProvider provider; // OK: the function is marked as experimental
* // ...
* }
*
* void displayDate() {
* System.out.println(getDate()); // Error: getDate() is experimental, acceptance is required
* }
* </code></pre>
*
*/
@Retention(CLASS)
@Target({ANNOTATION_TYPE})
public @interface Experimental {
/**
* Severity of the diagnostic that should be reported on usages of experimental API which did
* not explicitly accept the experimental aspect of that API either by using
* {@link UseExperimental} or by being annotated with the corresponding marker annotation.
*/
enum Level {
/**
* Specifies that a warning should be reported on incorrect usages of this experimental API.
*/
WARNING,
/**
* Specifies that an error should be reported on incorrect usages of this experimental API.
*/
ERROR,
}
/**
* Defines the reporting level for incorrect usages of this experimental API.
*/
Level level() default Level.ERROR;
}