VancedMicroG/play-services-tasks/src/main/java/com/google/android/gms/tasks/Continuation.java

69 lines
2.6 KiB
Java

/*
* Copyright (C) 2013-2017 microG Project Team
*
* 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.google.android.gms.tasks;
import org.microg.gms.common.PublicApi;
/**
* A function that is called to continue execution after completion of a {@link Task}.
*
* @see Task#continueWith(Continuation)
* @see Task#continueWithTask(Continuation)
*/
@PublicApi
public interface Continuation<TResult, TContinuationResult> {
/**
* Returns the result of applying this Continuation to {@code task}.
* <p/>
* To propagate failure from the completed Task call {@link Task#getResult()} and allow the
* {@link RuntimeExecutionException} to propagate. The RuntimeExecutionException will be
* unwrapped such that the Task returned by {@link Task#continueWith(Continuation)} or
* {@link Task#continueWithTask(Continuation)} fails with the original exception.
* <p/>
* To suppress specific failures call {@link Task#getResult(Class)} and catch the exception
* types of interest:
* <pre>task.continueWith(new Continuation<String, String>() {
* @Override
* public String then(Task<String> task) {
* try {
* return task.getResult(IOException.class);
* } catch (FileNotFoundException e) {
* return "Not found";
* } catch (IOException e) {
* return "Read failed";
* }
* }
* }</pre>
* <p/>
* To suppress all failures guard any calls to {@link Task#getResult()} with {@link Task#isSuccessful()}:
* <pre>task.continueWith(new Continuation<String, String>() {
* @Override
* public String then(Task<String> task) {
* if (task.isSuccessful()) {
* return task.getResult();
* } else {
* return DEFAULT_VALUE;
* }
* }
* }</pre>
*
* @param task the completed Task. Never null
* @throws Exception if the result couldn't be produced
*/
TContinuationResult then(Task<TResult> task);
}