Gets a value from the Future . - Java java.util.concurrent

Java examples for java.util.concurrent:Future

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Description

Gets a value from the Future .

Demo Code

/*/*  w ww  .  j av a 2 s  . co  m*/
 * Copyright 2004-2010 the Seasar Foundation and the Others.
 *
 * 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.java2s;
import java.lang.reflect.UndeclaredThrowableException;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.Future;

public class Main {
    /**
     * Gets a value from the {@link Future}.
     * 
     * @param <T>
     *            the value type
     * 
     * @param future
     *            the future
     * @return a value
     * @throws Exception
     *             if an exception occurred
     */
    public static <T> T get(Future<T> future) throws Exception {
        if (future == null) {
            throw new NullPointerException(
                    "The future parameter must not be null.");
        }
        try {
            return future.get();
        } catch (ExecutionException e) {
            Throwable cause = e.getCause();
            if (cause instanceof RuntimeException) {
                throw (RuntimeException) cause;
            } else if (cause instanceof Error) {
                throw (Error) cause;
            } else if (cause instanceof Exception) {
                throw (Exception) cause;
            }
            throw new UndeclaredThrowableException(cause);
        }
    }
}

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