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.] * * --------- * Year.java * --------- * (C) Copyright 2001-2012, by Object Refinery Limited. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * * Changes * ------- * 11-Oct-2001 : Version 1 (DG); * 14-Nov-2001 : Override for toString() method (DG); * 19-Dec-2001 : Added a new constructor as suggested by Paul English (DG); * 29-Jan-2002 : Worked on parseYear() method (DG); * 14-Feb-2002 : Fixed bug in Year(Date) constructor (DG); * 26-Feb-2002 : Changed getStart(), getMiddle() and getEnd() methods to * evaluate with reference to a particular time zone (DG); * 19-Mar-2002 : Changed API for TimePeriod classes (DG); * 10-Sep-2002 : Added getSerialIndex() method (DG); * 04-Oct-2002 : Fixed errors reported by Checkstyle (DG); * 10-Jan-2003 : Changed base class and method names (DG); * 05-Mar-2003 : Fixed bug in getFirstMillisecond() picked up in JUnit * tests (DG); * 13-Mar-2003 : Moved to com.jrefinery.data.time package, and implemented * Serializable (DG); * 21-Oct-2003 : Added hashCode() method (DG); * ------------- JFREECHART 1.0.x --------------------------------------------- * 05-Oct-2006 : Updated API docs (DG); * 06-Oct-2006 : Refactored to cache first and last millisecond values (DG); * 16-Sep-2008 : Extended range of valid years, and deprecated * DEFAULT_TIME_ZONE (DG); * 25-Nov-2008 : Added new constructor with Locale (DG); * 05-Jul-2012 : Removed JRE 1.3.1 code (DG); * */ package org.jfree.data.time; import java.io.Serializable; import java.util.Calendar; import java.util.Date; import java.util.Locale; import java.util.TimeZone; /** * Represents a year in the range -9999 to 9999. This class is immutable, * which is a requirement for all {@link RegularTimePeriod} subclasses. */ public class Year extends RegularTimePeriod implements Serializable { /** * The minimum year value. * * @since 1.0.11 */ public static final int MINIMUM_YEAR = -9999; /** * The maximum year value. * * @since 1.0.11 */ public static final int MAXIMUM_YEAR = 9999; /** For serialization. */ private static final long serialVersionUID = -7659990929736074836L; /** The year. */ private short year; /** The first millisecond. */ private long firstMillisecond; /** The last millisecond. */ private long lastMillisecond; /** * Creates a new <code>Year</code>, based on the current system date/time. */ public Year() { this(new Date()); } /** * Creates a time period representing a single year. * * @param year the year. */ public Year(int year) { if ((year < Year.MINIMUM_YEAR) || (year > Year.MAXIMUM_YEAR)) { throw new IllegalArgumentException("Year constructor: year (" + year + ") outside valid range."); } this.year = (short) year; peg(Calendar.getInstance()); } /** * Creates a new <code>Year</code>, based on a particular instant in time, * using the default time zone. * * @param time the time (<code>null</code> not permitted). * * @see #Year(Date, TimeZone) */ public Year(Date time) { this(time, TimeZone.getDefault()); } /** * Constructs a year, based on a particular instant in time and a time zone. * * @param time the time (<code>null</code> not permitted). * @param zone the time zone. * * @deprecated Since 1.0.12, use {@link #Year(Date, TimeZone, Locale)} * instead. */ public Year(Date time, TimeZone zone) { this(time, zone, Locale.getDefault()); } /** * Creates a new <code>Year</code> instance, for the specified time zone * and locale. * * @param time the current time (<code>null</code> not permitted). * @param zone the time zone. * @param locale the locale. * * @since 1.0.12 */ public Year(Date time, TimeZone zone, Locale locale) { Calendar calendar = Calendar.getInstance(zone, locale); calendar.setTime(time); this.year = (short) calendar.get(Calendar.YEAR); peg(calendar); } /** * Returns the year. * * @return The year. */ public int getYear() { return this.year; } /** * Returns the first millisecond of the year. This will be determined * relative to the time zone specified in the constructor, or in the * calendar instance passed in the most recent call to the * {@link #peg(Calendar)} method. * * @return The first millisecond of the year. * * @see #getLastMillisecond() */ @Override public long getFirstMillisecond() { return this.firstMillisecond; } /** * Returns the last millisecond of the year. This will be * determined relative to the time zone specified in the constructor, or * in the calendar instance passed in the most recent call to the * {@link #peg(Calendar)} method. * * @return The last millisecond of the year. * * @see #getFirstMillisecond() */ @Override public long getLastMillisecond() { return this.lastMillisecond; } /** * Recalculates the start date/time and end date/time for this time period * relative to the supplied calendar (which incorporates a time zone). * * @param calendar the calendar (<code>null</code> not permitted). * * @since 1.0.3 */ @Override public void peg(Calendar calendar) { this.firstMillisecond = getFirstMillisecond(calendar); this.lastMillisecond = getLastMillisecond(calendar); } /** * Returns the year preceding this one. * * @return The year preceding this one (or <code>null</code> if the * current year is -9999). */ @Override public RegularTimePeriod previous() { if (this.year > Year.MINIMUM_YEAR) { return new Year(this.year - 1); } else { return null; } } /** * Returns the year following this one. * * @return The year following this one (or <code>null</code> if the current * year is 9999). */ @Override public RegularTimePeriod next() { if (this.year < Year.MAXIMUM_YEAR) { return new Year(this.year + 1); } else { return null; } } /** * Returns a serial index number for the year. * <P> * The implementation simply returns the year number (e.g. 2002). * * @return The serial index number. */ @Override public long getSerialIndex() { return this.year; } /** * Returns the first millisecond of the year, evaluated using the supplied * calendar (which determines the time zone). * * @param calendar the calendar (<code>null</code> not permitted). * * @return The first millisecond of the year. * * @throws NullPointerException if <code>calendar</code> is * <code>null</code>. */ @Override public long getFirstMillisecond(Calendar calendar) { calendar.set(this.year, Calendar.JANUARY, 1, 0, 0, 0); calendar.set(Calendar.MILLISECOND, 0); return calendar.getTimeInMillis(); } /** * Returns the last millisecond of the year, evaluated using the supplied * calendar (which determines the time zone). * * @param calendar the calendar (<code>null</code> not permitted). * * @return The last millisecond of the year. * * @throws NullPointerException if <code>calendar</code> is * <code>null</code>. */ @Override public long getLastMillisecond(Calendar calendar) { calendar.set(this.year, Calendar.DECEMBER, 31, 23, 59, 59); calendar.set(Calendar.MILLISECOND, 999); return calendar.getTimeInMillis(); } /** * Tests the equality of this <code>Year</code> object to an arbitrary * object. Returns <code>true</code> if the target is a <code>Year</code> * instance representing the same year as this object. In all other cases, * returns <code>false</code>. * * @param obj the object (<code>null</code> permitted). * * @return <code>true</code> if the year of this and the object are the * same. */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof Year)) { return false; } Year that = (Year) obj; return (this.year == that.year); } /** * Returns a hash code for this object instance. The approach described by * Joshua Bloch in "Effective Java" has been used here: * <p> * <code>http://developer.java.sun.com/developer/Books/effectivejava * /Chapter3.pdf</code> * * @return A hash code. */ @Override public int hashCode() { int result = 17; int c = this.year; result = 37 * result + c; return result; } /** * Returns an integer indicating the order of this <code>Year</code> object * relative to the specified object: * * negative == before, zero == same, positive == after. * * @param o1 the object to compare. * * @return negative == before, zero == same, positive == after. */ @Override public int compareTo(Object o1) { int result; // CASE 1 : Comparing to another Year object // ----------------------------------------- if (o1 instanceof Year) { Year y = (Year) o1; result = this.year - y.getYear(); } // CASE 2 : Comparing to another TimePeriod object // ----------------------------------------------- else if (o1 instanceof RegularTimePeriod) { // more difficult case - evaluate later... result = 0; } // CASE 3 : Comparing to a non-TimePeriod object // --------------------------------------------- else { // consider time periods to be ordered after general objects result = 1; } return result; } /** * Returns a string representing the year.. * * @return A string representing the year. */ @Override public String toString() { return Integer.toString(this.year); } /** * Parses the string argument as a year. * <P> * The string format is YYYY. * * @param s a string representing the year. * * @return <code>null</code> if the string is not parseable, the year * otherwise. */ public static Year parseYear(String s) { // parse the string... int y; try { y = Integer.parseInt(s.trim()); } catch (NumberFormatException e) { throw new TimePeriodFormatException("Cannot parse string."); } // create the year... try { return new Year(y); } catch (IllegalArgumentException e) { throw new TimePeriodFormatException("Year outside valid range."); } } }