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This is a small extension to Google's Guava library to allow for the creation of configurable retrying strategies for an arbitrary function call, such as something that talks to a remote service with flaky uptime.

There is a newer version: 2.0.0

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/*
 * Copyright 2012-2013 Ray Holder
 *
 * 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.github.rholder.retry;

import java.util.concurrent.ExecutionException;

/**
 * An attempt of a call, which resulted either in a result returned by the call,
 * or in a Throwable thrown by the call.
 * @author JB
 *
 * @param  The type returned by the wrapped callable.
 */
public interface Attempt {

    /**
     * Returns the result of the attempt, if any.
     * @return the result of the attempt
     * @throws ExecutionException if an exception was thrown by the attempt. The thrown
     * exception is set as the cause of the ExecutionException
     */
    public V get() throws ExecutionException;

    /**
     * Tells if the call returned a result or not
     * @return true if the call returned a result, false
     * if it threw an exception
     */
    public boolean hasResult();

    /**
     * Tells if the call threw an exception or not
     * @return true if the call threw an exception, false
     * if it returned a result
     */
    public boolean hasException();

    /**
     * Gets the result of the call
     * @return the result of the call
     * @throws IllegalStateException if the call didn't return a result, but threw an exception,
     * as indicated by {@link #hasResult()}
     */
    public V getResult() throws IllegalStateException;

    /**
     * Gets the exception thrown by the call
     * @return the exception thrown by the call
     * @throws IllegalStateException if the call didn't throw an exception,
     * as indicated by {@link #hasException()}
     */
    public Throwable getExceptionCause() throws IllegalStateException;
}