FutureCallback.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.test.espresso.web.util.concurrent;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import com.google.common.util.concurrent.ListenableFuture;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

/**
 * Forked from androidx.camera package to avoid full Guava dependency.
 *
 * <p>A callback for accepting the results of a {@link java.util.concurrent.Future} computation
 * asynchronously.
 *
 * <p>To attach to a {@link ListenableFuture} use {@link Futures#addCallback}.
 *
 * @author Anthony Zana
 * @since 10.0
 * @param <V>
 */
interface FutureCallback<V> {
  /** Invoked with the result of the {@code Future} computation when it is successful. */
  void onSuccess(@Nullable V result);

  /**
   * Invoked when a {@code Future} computation fails or is canceled.
   *
   * <p>If the future's {@link Future#get() get} method throws an {@link ExecutionException} with a
   * non-{@code null} cause, then the cause is passed to this method. Any other thrown object is
   * passed unaltered.
   */
  void onFailure(@NonNull Throwable t);
}