Java example source code file (FixedGenerationCount.java)

This example Java source code file (FixedGenerationCount.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

fixedgenerationcount, numberistoosmallexception, population, stoppingcondition

The FixedGenerationCount.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 org.apache.commons.math3.exception.NumberIsTooSmallException;

/**
 * Stops after a fixed number of generations. Each time {@link #isSatisfied(Population)} is invoked, a generation
 * counter is incremented. Once the counter reaches the configured <code>maxGenerations value,
 * {@link #isSatisfied(Population)} returns true.
 *
 * @since 2.0
 */
public class FixedGenerationCount implements StoppingCondition {
    /** Number of generations that have passed */
    private int numGenerations = 0;

    /** Maximum number of generations (stopping criteria) */
    private final int maxGenerations;

    /**
     * Create a new FixedGenerationCount instance.
     *
     * @param maxGenerations number of generations to evolve
     * @throws NumberIsTooSmallException if the number of generations is < 1
     */
    public FixedGenerationCount(final int maxGenerations) throws NumberIsTooSmallException {
        if (maxGenerations <= 0) {
            throw new NumberIsTooSmallException(maxGenerations, 1, true);
        }
        this.maxGenerations = maxGenerations;
    }

    /**
     * Determine whether or not the given number of generations have passed. Increments the number of generations
     * counter if the maximum has not been reached.
     *
     * @param population ignored (no impact on result)
     * @return <code>true IFF the maximum number of generations has been exceeded
     */
    public boolean isSatisfied(final Population population) {
        if (this.numGenerations < this.maxGenerations) {
            numGenerations++;
            return false;
        }
        return true;
    }

    /**
     * Returns the number of generations that have already passed.
     * @return the number of generations that have passed
     */
    public int getNumGenerations() {
        return numGenerations;
    }

}