Manager.java
/*
* Copyright 2021 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.managers;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.RestrictTo;
import java.lang.reflect.Constructor;
/**
* A manager that extends the services provided by {@link androidx.car.app.CarContext}. These
* manager can be obtained from {@link androidx.car.app.CarContext#getCarService(Class)} or
* {@link androidx.car.app.CarContext#getCarService(String)}
*/
public interface Manager {
/**
* Helper method to create managers by reflection
*
* @param clazz interface manager expected to receive
* @param className class name of the manager
* @param args arguments to send to the manager
* @param <U> manager type
* @return an instance of the given manager, or null if the given class name is not found.
* @throws IllegalStateException if the class exists, but there was an error trying to
* instantiate it.
*
*/
@RestrictTo(RestrictTo.Scope.LIBRARY)
@Nullable
static <U extends Manager> U create(@NonNull Class<U> clazz, @NonNull String className,
@NonNull Object ... args) {
try { // Check for automotive library first.
Class<?> c = Class.forName(className);
Class<?>[] argsTypes = new Class<?>[args.length];
for (int i = 0; i < args.length; i++) {
argsTypes[i] = args[i].getClass();
}
Constructor<?> ctor = c.getConstructor(argsTypes);
return clazz.cast(ctor.newInstance(args));
} catch (ClassNotFoundException e) {
// Not found, fall through.
return null;
} catch (ReflectiveOperationException e) {
// Something went wrong with accessing the constructor or calling newInstance().
throw new IllegalStateException("Mismatch with artifact", e);
}
}
}