Java example source code file (ListPopulation.java)

This example Java source code file (ListPopulation.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

arraylist, chromosome, collection, deprecated, iterator, list, listpopulation, notpositiveexception, nullargumentexception, numberistoolargeexception, numberistoosmallexception, override, string, util

The ListPopulation.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.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Iterator;
import java.util.List;

import org.apache.commons.math3.exception.util.LocalizedFormats;
import org.apache.commons.math3.exception.NotPositiveException;
import org.apache.commons.math3.exception.NullArgumentException;
import org.apache.commons.math3.exception.NumberIsTooLargeException;
import org.apache.commons.math3.exception.NumberIsTooSmallException;

/**
 * Population of chromosomes represented by a {@link List}.
 *
 * @since 2.0
 */
public abstract class ListPopulation implements Population {

    /** List of chromosomes */
    private List<Chromosome> chromosomes;

    /** maximal size of the population */
    private int populationLimit;

    /**
     * Creates a new ListPopulation instance and initializes its inner chromosome list.
     *
     * @param populationLimit maximal size of the population
     * @throws NotPositiveException if the population limit is not a positive number (< 1)
     */
    public ListPopulation(final int populationLimit) throws NotPositiveException {
        this(Collections.<Chromosome> emptyList(), populationLimit);
    }

    /**
     * Creates a new ListPopulation instance.
     * <p>
     * Note: the chromosomes of the specified list are added to the population.
     *
     * @param chromosomes list of chromosomes to be added to the population
     * @param populationLimit maximal size of the population
     * @throws NullArgumentException if the list of chromosomes is {@code null}
     * @throws NotPositiveException if the population limit is not a positive number (< 1)
     * @throws NumberIsTooLargeException if the list of chromosomes exceeds the population limit
     */
    public ListPopulation(final List<Chromosome> chromosomes, final int populationLimit)
        throws NullArgumentException, NotPositiveException, NumberIsTooLargeException {

        if (chromosomes == null) {
            throw new NullArgumentException();
        }
        if (populationLimit <= 0) {
            throw new NotPositiveException(LocalizedFormats.POPULATION_LIMIT_NOT_POSITIVE, populationLimit);
        }
        if (chromosomes.size() > populationLimit) {
            throw new NumberIsTooLargeException(LocalizedFormats.LIST_OF_CHROMOSOMES_BIGGER_THAN_POPULATION_SIZE,
                                                chromosomes.size(), populationLimit, false);
        }
        this.populationLimit = populationLimit;
        this.chromosomes = new ArrayList<Chromosome>(populationLimit);
        this.chromosomes.addAll(chromosomes);
    }

    /**
     * Sets the list of chromosomes.
     * <p>
     * Note: this method removes all existing chromosomes in the population and adds all chromosomes
     * of the specified list to the population.
     *
     * @param chromosomes the list of chromosomes
     * @throws NullArgumentException if the list of chromosomes is {@code null}
     * @throws NumberIsTooLargeException if the list of chromosomes exceeds the population limit
     * @deprecated use {@link #addChromosomes(Collection)} instead
     */
    @Deprecated
    public void setChromosomes(final List<Chromosome> chromosomes)
        throws NullArgumentException, NumberIsTooLargeException {

        if (chromosomes == null) {
            throw new NullArgumentException();
        }
        if (chromosomes.size() > populationLimit) {
            throw new NumberIsTooLargeException(LocalizedFormats.LIST_OF_CHROMOSOMES_BIGGER_THAN_POPULATION_SIZE,
                                                chromosomes.size(), populationLimit, false);
        }
        this.chromosomes.clear();
        this.chromosomes.addAll(chromosomes);
    }

    /**
     * Add a {@link Collection} of chromosomes to this {@link Population}.
     * @param chromosomeColl a {@link Collection} of chromosomes
     * @throws NumberIsTooLargeException if the population would exceed the population limit when
     * adding this chromosome
     * @since 3.1
     */
    public void addChromosomes(final Collection<Chromosome> chromosomeColl) throws NumberIsTooLargeException {
        if (chromosomes.size() + chromosomeColl.size() > populationLimit) {
            throw new NumberIsTooLargeException(LocalizedFormats.LIST_OF_CHROMOSOMES_BIGGER_THAN_POPULATION_SIZE,
                                                chromosomes.size(), populationLimit, false);
        }
        this.chromosomes.addAll(chromosomeColl);
    }

    /**
     * Returns an unmodifiable list of the chromosomes in this population.
     * @return the unmodifiable list of chromosomes
     */
    public List<Chromosome> getChromosomes() {
        return Collections.unmodifiableList(chromosomes);
    }

    /**
     * Access the list of chromosomes.
     * @return the list of chromosomes
     * @since 3.1
     */
    protected List<Chromosome> getChromosomeList() {
        return chromosomes;
    }

    /**
     * Add the given chromosome to the population.
     *
     * @param chromosome the chromosome to add.
     * @throws NumberIsTooLargeException if the population would exceed the {@code populationLimit} after
     *   adding this chromosome
     */
    public void addChromosome(final Chromosome chromosome) throws NumberIsTooLargeException {
        if (chromosomes.size() >= populationLimit) {
            throw new NumberIsTooLargeException(LocalizedFormats.LIST_OF_CHROMOSOMES_BIGGER_THAN_POPULATION_SIZE,
                                                chromosomes.size(), populationLimit, false);
        }
        this.chromosomes.add(chromosome);
    }

    /**
     * Access the fittest chromosome in this population.
     * @return the fittest chromosome.
     */
    public Chromosome getFittestChromosome() {
        // best so far
        Chromosome bestChromosome = this.chromosomes.get(0);
        for (Chromosome chromosome : this.chromosomes) {
            if (chromosome.compareTo(bestChromosome) > 0) {
                // better chromosome found
                bestChromosome = chromosome;
            }
        }
        return bestChromosome;
    }

    /**
     * Access the maximum population size.
     * @return the maximum population size.
     */
    public int getPopulationLimit() {
        return this.populationLimit;
    }

    /**
     * Sets the maximal population size.
     * @param populationLimit maximal population size.
     * @throws NotPositiveException if the population limit is not a positive number (< 1)
     * @throws NumberIsTooSmallException if the new population size is smaller than the current number
     *   of chromosomes in the population
     */
    public void setPopulationLimit(final int populationLimit) throws NotPositiveException, NumberIsTooSmallException {
        if (populationLimit <= 0) {
            throw new NotPositiveException(LocalizedFormats.POPULATION_LIMIT_NOT_POSITIVE, populationLimit);
        }
        if (populationLimit < chromosomes.size()) {
            throw new NumberIsTooSmallException(populationLimit, chromosomes.size(), true);
        }
        this.populationLimit = populationLimit;
    }

    /**
     * Access the current population size.
     * @return the current population size.
     */
    public int getPopulationSize() {
        return this.chromosomes.size();
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public String toString() {
        return this.chromosomes.toString();
    }

    /**
     * Returns an iterator over the unmodifiable list of chromosomes.
     * <p>Any call to {@link Iterator#remove()} will result in a {@link UnsupportedOperationException}.

     *
     * @return chromosome iterator
     */
    public Iterator<Chromosome> iterator() {
        return getChromosomes().iterator();
    }
}