Java tutorial
/* =========================================================== * JFreeChart : a free chart library for the Java(tm) platform * =========================================================== * * (C) Copyright 2000-2013, by Object Refinery Limited and Contributors. * * Project Info: http://www.jfree.org/jfreechart/index.html * * This library is free software; you can redistribute it and/or modify it * under the terms of the GNU Lesser General Public License as published by * the Free Software Foundation; either version 2.1 of the License, or * (at your option) any later version. * * This library is distributed in the hope that it will be useful, but * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public * License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, * USA. * * [Oracle and Java are registered trademarks of Oracle and/or its affiliates. * Other names may be trademarks of their respective owners.] * * --------------------- * SimpleTimePeriod.java * --------------------- * (C) Copyright 2002-2008, by Object Refinery Limited and Contributors. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * * Changes * ------- * 07-Oct-2002 : Added Javadocs (DG); * 10-Jan-2003 : Renamed TimeAllocation --> SimpleTimePeriod (DG); * 13-Mar-2003 : Added equals() method, and Serializable interface (DG); * 21-Oct-2003 : Added hashCode() method (DG); * 27-Jan-2005 : Implemented Comparable, to enable this class to be used * in the TimeTableXYDataset class (DG); * 02-Jun-2008 : Fixed problem with fields being mutable (DG); * */ package org.jfree.data.time; import java.io.Serializable; import java.util.Date; /** * An arbitrary period of time, measured to millisecond precision using * <code>java.util.Date</code>. * <p> * This class is intentionally immutable (that is, once constructed, you cannot * alter the start and end attributes). */ public class SimpleTimePeriod implements TimePeriod, Comparable, Serializable { /** For serialization. */ private static final long serialVersionUID = 8684672361131829554L; /** The start date/time. */ private long start; /** The end date/time. */ private long end; /** * Creates a new time allocation. * * @param start the start date/time in milliseconds. * @param end the end date/time in milliseconds. */ public SimpleTimePeriod(long start, long end) { if (start > end) { throw new IllegalArgumentException("Requires start <= end."); } this.start = start; this.end = end; } /** * Creates a new time allocation. * * @param start the start date/time (<code>null</code> not permitted). * @param end the end date/time (<code>null</code> not permitted). */ public SimpleTimePeriod(Date start, Date end) { this(start.getTime(), end.getTime()); } /** * Returns the start date/time. * * @return The start date/time (never <code>null</code>). */ @Override public Date getStart() { return new Date(this.start); } /** * Returns the start date/time in milliseconds. * * @return The start. * * @since 1.0.10. */ public long getStartMillis() { return this.start; } /** * Returns the end date/time. * * @return The end date/time (never <code>null</code>). */ @Override public Date getEnd() { return new Date(this.end); } /** * Returns the end date/time in milliseconds. * * @return The end. * * @since 1.0.10. */ public long getEndMillis() { return this.end; } /** * Tests this time period instance for equality with an arbitrary object. * The object is considered equal if it is an instance of {@link TimePeriod} * and it has the same start and end dates. * * @param obj the other object (<code>null</code> permitted). * * @return A boolean. */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof TimePeriod)) { return false; } TimePeriod that = (TimePeriod) obj; if (!this.getStart().equals(that.getStart())) { return false; } if (!this.getEnd().equals(that.getEnd())) { return false; } return true; } /** * Returns an integer that indicates the relative ordering of two * time periods. * * @param obj the object (<code>null</code> not permitted). * * @return An integer. * * @throws ClassCastException if <code>obj</code> is not an instance of * {@link TimePeriod}. */ @Override public int compareTo(Object obj) { TimePeriod that = (TimePeriod) obj; long t0 = getStart().getTime(); long t1 = getEnd().getTime(); long m0 = t0 + (t1 - t0) / 2L; long t2 = that.getStart().getTime(); long t3 = that.getEnd().getTime(); long m1 = t2 + (t3 - t2) / 2L; if (m0 < m1) { return -1; } else if (m0 > m1) { return 1; } else { if (t0 < t2) { return -1; } else if (t0 > t2) { return 1; } else { if (t1 < t3) { return -1; } else if (t1 > t3) { return 1; } else { return 0; } } } } /** * Returns a hash code for this object instance. The approach described by * Joshua Bloch in "Effective Java" has been used here - see: * <p> * <code>http://developer.java.sun.com/ * developer/Books/effectivejava/Chapter3.pdf</code> * * @return A hash code. */ @Override public int hashCode() { int result = 17; result = 37 * result + (int) this.start; result = 37 * result + (int) this.end; return result; } }