001/* ===========================================================
002 * JFreeChart : a free chart library for the Java(tm) platform
003 * ===========================================================
004 *
005 * (C) Copyright 2000-2022, by David Gilbert and Contributors.
006 *
007 * Project Info:  http://www.jfree.org/jfreechart/index.html
008 *
009 * This library is free software; you can redistribute it and/or modify it
010 * under the terms of the GNU Lesser General Public License as published by
011 * the Free Software Foundation; either version 2.1 of the License, or
012 * (at your option) any later version.
013 *
014 * This library is distributed in the hope that it will be useful, but
015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
017 * License for more details.
018 *
019 * You should have received a copy of the GNU Lesser General Public
020 * License along with this library; if not, write to the Free Software
021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
022 * USA.
023 *
024 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. 
025 * Other names may be trademarks of their respective owners.]
026 *
027 * ---------------------
028 * SimpleTimePeriod.java
029 * ---------------------
030 * (C) Copyright 2002-2022, by David Gilbert and Contributors.
031 *
032 * Original Author:  David Gilbert;
033 * Contributor(s):   -;
034 *
035 */
036
037package org.jfree.data.time;
038
039import java.io.Serializable;
040import java.util.Date;
041
042/**
043 * An arbitrary period of time, measured to millisecond precision using
044 * {@code java.util.Date}.
045 * <p>
046 * This class is intentionally immutable (that is, once constructed, you cannot
047 * alter the start and end attributes).
048 */
049public class SimpleTimePeriod implements TimePeriod, Comparable, Serializable {
050
051    /** For serialization. */
052    private static final long serialVersionUID = 8684672361131829554L;
053
054    /** The start date/time. */
055    private long start;
056
057    /** The end date/time. */
058    private long end;
059
060    /**
061     * Creates a new time allocation.
062     *
063     * @param start  the start date/time in milliseconds.
064     * @param end  the end date/time in milliseconds.
065     */
066    public SimpleTimePeriod(long start, long end) {
067        if (start > end) {
068            throw new IllegalArgumentException("Requires start <= end.");
069        }
070        this.start = start;
071        this.end = end;
072    }
073
074    /**
075     * Creates a new time allocation.
076     *
077     * @param start  the start date/time ({@code null} not permitted).
078     * @param end  the end date/time ({@code null} not permitted).
079     */
080    public SimpleTimePeriod(Date start, Date end) {
081        this(start.getTime(), end.getTime());
082    }
083
084    /**
085     * Returns the start date/time.
086     *
087     * @return The start date/time (never {@code null}).
088     */
089    @Override
090    public Date getStart() {
091        return new Date(this.start);
092    }
093
094    /**
095     * Returns the start date/time in milliseconds.
096     *
097     * @return The start.
098     *
099     * @since 1.0.10.
100     */
101    public long getStartMillis() {
102        return this.start;
103    }
104
105    /**
106     * Returns the end date/time.
107     *
108     * @return The end date/time (never {@code null}).
109     */
110    @Override
111    public Date getEnd() {
112        return new Date(this.end);
113    }
114
115    /**
116     * Returns the end date/time in milliseconds.
117     *
118     * @return The end.
119     *
120     * @since 1.0.10.
121     */
122    public long getEndMillis() {
123        return this.end;
124    }
125
126    /**
127     * Tests this time period instance for equality with an arbitrary object.
128     * The object is considered equal if it is an instance of {@link TimePeriod}
129     * and it has the same start and end dates.
130     *
131     * @param obj  the other object ({@code null} permitted).
132     *
133     * @return A boolean.
134     */
135    @Override
136    public boolean equals(Object obj) {
137        if (obj == this) {
138            return true;
139        }
140        if (!(obj instanceof TimePeriod)) {
141            return false;
142        }
143        TimePeriod that = (TimePeriod) obj;
144        if (!this.getStart().equals(that.getStart())) {
145            return false;
146        }
147        if (!this.getEnd().equals(that.getEnd())) {
148            return false;
149        }
150        return true;
151    }
152
153    /**
154     * Returns an integer that indicates the relative ordering of two
155     * time periods.
156     *
157     * @param obj  the object ({@code null} not permitted).
158     *
159     * @return An integer.
160     *
161     * @throws ClassCastException if {@code obj} is not an instance of
162     *                            {@link TimePeriod}.
163     */
164    @Override
165    public int compareTo(Object obj) {
166        TimePeriod that = (TimePeriod) obj;
167        long t0 = getStart().getTime();
168        long t1 = getEnd().getTime();
169        long m0 = t0 + (t1 - t0) / 2L;
170        long t2 = that.getStart().getTime();
171        long t3 = that.getEnd().getTime();
172        long m1 = t2 + (t3 - t2) / 2L;
173        if (m0 < m1) {
174            return -1;
175        }
176        else if (m0 > m1) {
177            return 1;
178        }
179        else {
180            if (t0 < t2) {
181                return -1;
182            }
183            else if (t0 > t2) {
184                return 1;
185            }
186            else {
187                if (t1 < t3) {
188                    return -1;
189                }
190                else if (t1 > t3) {
191                    return 1;
192                }
193                else {
194                    return 0;
195                }
196            }
197        }
198    }
199
200    /**
201     * Returns a hash code for this object instance.  The approach described by
202     * Joshua Bloch in "Effective Java" has been used here - see:
203     * <p>
204     * {@code http://developer.java.sun.com/
205     * developer/Books/effectivejava/Chapter3.pdf}
206     *
207     * @return A hash code.
208     */
209    @Override
210    public int hashCode() {
211        int result = 17;
212        result = 37 * result + (int) this.start;
213        result = 37 * result + (int) this.end;
214        return result;
215    }
216
217}