DoubleData.java

// <editor-fold defaultstate="collapsed" desc="license">
/*
 * Copyright (c) 2014, Karl H. Beckers
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * * Neither the name of the <ORGANIZATION> nor the names of its contributors
 *   may be used to endorse or promote products derived from this software
 *   without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 **/
// </editor-fold>
package net.jarre_de_the.griffin.types.data;

import java.io.IOException;
import java.io.RandomAccessFile;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * Implementation of the DOUBLE. The GFF DOUBLE is an 8 byte double precision floating point value.
 * <p>
 * @author charly4711
 */
public class DoubleData extends AbstractFixedLengthData<Double, DoubleData>
        implements NumberData<Double>, Cloneable {

    /**
     * The length of a DOUBLE in bytes
     */
    public static final int LENGTH = 8;
    private static final Logger LOGGER = LoggerFactory.getLogger(DoubleData.class);
    private double value = 0.0d;

    /*
     *
     * constructors
     *
     */
    protected DoubleData() {
    }

    /**
     * Creates a new instance of {@code DoubleData} and sets a defined value.
     * <p>
     * @param d The value to set. The Java primitive double corresponds well with the DOUBLE.
     * @see #setValue(double d)
     */
    public DoubleData(double d) {
        setValue(d);
    }

    /*
     *
     * read from file
     *
     */
    /**
     * Creates a new instance of {@code DoubleData} based on the data read from the file passed. Note that the contents
     * are read from whatever position the file pointer is at.
     * <p>
     * @param in An open {@code RandomAccessFile}.
     * @return
     * @throws java.io.IOException If there are any I/O related problems with file access to in.
     */
    public static DoubleData read(RandomAccessFile in)
            throws IOException {
        DoubleData d = new DoubleData();
        d.setValue((double)read(in, Double.class));
        return d;
    }

    /*
     *
     * setter
     *
     */
    /**
     * Sets this instance's value.
     * <p>
     * @param d The value to set.
     */
    private void setValue(double d) {
        value = d;
    }

    /*
     *
     * getter
     *
     */
    /**
     * Returns this instance's numeric value as a double.
     * <p>
     * @return The numeric value of this instance.
     */
    @Override
    public Double getValueAsNumber() {
        return value;
    }

    /**
     * Returns this instance's bit-field value as a byte array in the same order it would be stored in a GFF file.
     * <p>
     * @return This instance's value as a bit field split into 8 bytes.
     */
    @Override
    public byte[] getValueAsByteArray() {
        return super.getValueAsByteArray(value);
    }

    @Override
    public Double getValue() {
        return value;
    }

    /*
     *
     * utility
     *
     */
    @Override
    public int length() {
        return LENGTH;
    }

    /**
     * Overrides the {@code java.lang.Object} method to ensure we always get back an instance of {@code DoubleData}
     * rather than just {@code Object}.
     * <p>
     * @return A deep copy of this object.
     * @throws java.lang.CloneNotSupportedException
     */
    @Override
    public DoubleData clone() throws CloneNotSupportedException {
        LOGGER.debug("Cloning object");
        DoubleData clone = (DoubleData) super.clone();
        clone.setValue(value);

        return clone;
    }

    /**
     * Overrides the {@code java.lang.Object} method to make test for equality possible for this class.
     * <p>
     * @param compare The Object to compare this object with.
     * @return True if the objects have the same value, false if not.
     */
    @Override
    public boolean equals(Object compare) {
        if (compare == this) {
            return true;
        }

        if (!(compare instanceof DoubleData)) {
            return false;
        }

        DoubleData d = (DoubleData) compare;
        return d.getValueAsNumber().equals(this.getValueAsNumber());
    }

    /**
     * Overrides the {@code java.lang.Object} method to ensure we have a hash code consistent with the test for
     * equality. Because we have a full 8 byte long value but can only return a 4 byte int, we need to lose some date.
     * We do the same as the {@code java.lang.Long}, i. e. return an exclusive OR of the two halves of the long value.
     * <p>
     * <blockquote> {@code (int)(this.getLongValue()^(this.getLongValue()>>>32))}
     * </blockquote>
     * <p>
     * @return The hash returned is based on the value.
     */
    @Override
    public int hashCode() {
        LOGGER.debug("Creating int hashCode from long value");
        long l = Double.doubleToLongBits(value);
        return (int) (l ^ (l >>> 32));
    }

    @Override
    public String toString() {
        return Double.toString(getValueAsNumber());
    }
}