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Java example source code file (FixedElapsedTime.java)

This example Java source code file (FixedElapsedTime.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

fixedelapsedtime, numberistoosmallexception, population, stoppingcondition, threading, threads, timeunit

The FixedElapsedTime.java Java example source code

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.math3.genetics;

import java.util.concurrent.TimeUnit;

import org.apache.commons.math3.exception.NumberIsTooSmallException;

/**
 * Stops after a fixed amount of time has elapsed.
 * <p>
 * The first time {@link #isSatisfied(Population)} is invoked, the end time of the evolution is determined based on the
 * provided <code>maxTime value. Once the elapsed time reaches the configured maxTime value,
 * {@link #isSatisfied(Population)} returns true.
 *
 * @since 3.1
 */
public class FixedElapsedTime implements StoppingCondition {
    /** Maximum allowed time period (in nanoseconds). */
    private final long maxTimePeriod;

    /** The predetermined termination time (stopping condition). */
    private long endTime = -1;

    /**
     * Create a new {@link FixedElapsedTime} instance.
     *
     * @param maxTime maximum number of seconds generations are allowed to evolve
     * @throws NumberIsTooSmallException if the provided time is < 0
     */
    public FixedElapsedTime(final long maxTime) throws NumberIsTooSmallException {
        this(maxTime, TimeUnit.SECONDS);
    }

    /**
     * Create a new {@link FixedElapsedTime} instance.
     *
     * @param maxTime maximum time generations are allowed to evolve
     * @param unit {@link TimeUnit} of the maxTime argument
     * @throws NumberIsTooSmallException if the provided time is < 0
     */
    public FixedElapsedTime(final long maxTime, final TimeUnit unit) throws NumberIsTooSmallException {
        if (maxTime < 0) {
            throw new NumberIsTooSmallException(maxTime, 0, true);
        }
        maxTimePeriod = unit.toNanos(maxTime);
    }

    /**
     * Determine whether or not the maximum allowed time has passed.
     * The termination time is determined after the first generation.
     *
     * @param population ignored (no impact on result)
     * @return <code>true IFF the maximum allowed time period has elapsed
     */
    public boolean isSatisfied(final Population population) {
        if (endTime < 0) {
            endTime = System.nanoTime() + maxTimePeriod;
        }

        return System.nanoTime() >= endTime;
    }
}

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