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Java example source code file (PointValuePair.java)

This example Java source code file (PointValuePair.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

datatransferobject, double, object, pointvaluepair, serializable

The PointValuePair.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.optim;

import java.io.Serializable;
import org.apache.commons.math3.util.Pair;

/**
 * This class holds a point and the value of an objective function at
 * that point.
 *
 * @see PointVectorValuePair
 * @see org.apache.commons.math3.analysis.MultivariateFunction
 * @since 3.0
 */
public class PointValuePair extends Pair<double[], Double> implements Serializable {
    /** Serializable UID. */
    private static final long serialVersionUID = 20120513L;

    /**
     * Builds a point/objective function value pair.
     *
     * @param point Point coordinates. This instance will store
     * a copy of the array, not the array passed as argument.
     * @param value Value of the objective function at the point.
     */
    public PointValuePair(final double[] point,
                          final double value) {
        this(point, value, true);
    }

    /**
     * Builds a point/objective function value pair.
     *
     * @param point Point coordinates.
     * @param value Value of the objective function at the point.
     * @param copyArray if {@code true}, the input array will be copied,
     * otherwise it will be referenced.
     */
    public PointValuePair(final double[] point,
                          final double value,
                          final boolean copyArray) {
        super(copyArray ? ((point == null) ? null :
                           point.clone()) :
              point,
              value);
    }

    /**
     * Gets the point.
     *
     * @return a copy of the stored point.
     */
    public double[] getPoint() {
        final double[] p = getKey();
        return p == null ? null : p.clone();
    }

    /**
     * Gets a reference to the point.
     *
     * @return a reference to the internal array storing the point.
     */
    public double[] getPointRef() {
        return getKey();
    }

    /**
     * Replace the instance with a data transfer object for serialization.
     * @return data transfer object that will be serialized
     */
    private Object writeReplace() {
        return new DataTransferObject(getKey(), getValue());
    }

    /** Internal class used only for serialization. */
    private static class DataTransferObject implements Serializable {
        /** Serializable UID. */
        private static final long serialVersionUID = 20120513L;
        /**
         * Point coordinates.
         * @Serial
         */
        private final double[] point;
        /**
         * Value of the objective function at the point.
         * @Serial
         */
        private final double value;

        /** Simple constructor.
         * @param point Point coordinates.
         * @param value Value of the objective function at the point.
         */
        DataTransferObject(final double[] point, final double value) {
            this.point = point.clone();
            this.value = value;
        }

        /** Replace the deserialized data transfer object with a {@link PointValuePair}.
         * @return replacement {@link PointValuePair}
         */
        private Object readResolve() {
            return new PointValuePair(point, value, false);
        }
    }
}

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