src/com/android/contacts/util/AsyncTaskExecutor.java

/*
 * Copyright (C) 2011 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 com.android.contacts.util;

import android.os.AsyncTask;

import java.util.concurrent.Executor;

/**
 * Interface used to submit {@link AsyncTask} objects to run in the background.
 * <p>
 * This interface has a direct parallel with the {@link Executor} interface. It exists to decouple
 * the mechanics of AsyncTask submission from the description of how that AsyncTask will execute.
 * <p>
 * One immediate benefit of this approach is that testing becomes much easier, since it is easy to
 * introduce a mock or fake AsyncTaskExecutor in unit/integration tests, and thus inspect which
 * tasks have been submitted and control their execution in an orderly manner.
 * <p>
 * Another benefit in due course will be the management of the submitted tasks. An extension to this
 * interface is planned to allow Activities to easily cancel all the submitted tasks that are still
 * pending in the onDestroy() method of the Activity.
 */
public interface AsyncTaskExecutor {
    /**
     * Executes the given AsyncTask with the default Executor.
     * <p>
     * This method <b>must only be called from the ui thread</b>.
     * <p>
     * The identifier supplied is any Object that can be used to identify the task later. Most
     * commonly this will be an enum which the tests can also refer to. {@code null} is also
     * accepted, though of course this won't help in identifying the task later.
     */
    <T> AsyncTask<T, ?, ?> submit(Object identifier, AsyncTask<T, ?, ?> task, T... params);
}