Here you can find the source of exceptionallyCompletedFuture(final Throwable t)
public static <T> CompletionStage<T> exceptionallyCompletedFuture(final Throwable t)
//package com.java2s; /*-//from w w w . j a va 2 s .c o m * -\-\- * Spotify Styx Common * -- * Copyright (C) 2017 Spotify AB * -- * 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. * -/-/- */ import java.util.concurrent.CompletableFuture; import java.util.concurrent.CompletionStage; public class Main { public static <T> CompletionStage<T> exceptionallyCompletedFuture(final Throwable t) { CompletableFuture<T> future = new CompletableFuture<>(); future.completeExceptionally(t); return future; } }