RequiresCarApi.java
/*
* Copyright 2020 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.car.app.annotations;
import androidx.car.app.CarContext;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
/**
* Defines the minimum API level required to be able to use this model, field, or method.
*
* <p>Before using any of these elements, application must check that
* {@link CarContext#getCarAppApiLevel()} is equal or greater than the value of this annotation.
*
* <p>For example, if an application wants to use a newer template "Foo" marked with
* <code>@RequiresCarApi(2)</code> while maintain backwards compatibility with older hosts
* by using an older template "Bar" (<code>@RequiresHostApiLevel(1)</code>), they can do:
*
* <pre>
* if (getCarContext().getCarApiLevel() >= 2) {
* // Use new feature
* return Foo.Builder()....;
* } else {
* // Use supported fallback
* return Bar.Builder()....;
* }
* </pre>
*
* If a certain model or method has no {@link RequiresCarApi} annotation, it is assumed to
* be available in all car API levels.
*
* <h4>API stability</h4>
*
* New APIs that are introduced during alpha library releases should be used with extra caution.
* Specifically, apps should NOT use APIs in the following categories in their production APKs:
*
* <ul>
* <li>New APIs that are only available in alpha releases
* <li>APIs that are annotated with {@link ExperimentalCarApi}
* </ul>
*
* <p>As they are considered unstable or experimental, these APIs may change and potentially break
* your app when the host(s) are updated.
*/
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE, ElementType.CONSTRUCTOR, ElementType.FIELD, ElementType.METHOD})
public @interface RequiresCarApi {
/**
* The minimum API level required to be able to use this model, field or method. Applications
* shouldn't use any elements annotated with a {@link RequiresCarApi} greater than
* {@link CarContext#getCarAppApiLevel()}
*/
int value();
}