Java tutorial
/* =========================================================== * JFreeChart : a free chart library for the Java(tm) platform * =========================================================== * * (C) Copyright 2000-2014, 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.] * * --------- * Hour.java * --------- * (C) Copyright 2001-2014, by Object Refinery Limited. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): -; * * Changes * ------- * 11-Oct-2001 : Version 1 (DG); * 18-Dec-2001 : Changed order of parameters in constructor (DG); * 19-Dec-2001 : Added a new constructor as suggested by Paul English (DG); * 14-Feb-2002 : Fixed bug in Hour(Date) constructor (DG); * 26-Feb-2002 : Changed getStart(), getMiddle() and getEnd() methods to * evaluate with reference to a particular time zone (DG); * 15-Mar-2002 : Changed API (DG); * 16-Apr-2002 : Fixed small time zone bug in constructor (DG); * 10-Sep-2002 : Added getSerialIndex() method (DG); * 07-Oct-2002 : Fixed errors reported by Checkstyle (DG); * 10-Jan-2003 : Changed base class and method names (DG); * 13-Mar-2003 : Moved to com.jrefinery.data.time package, and implemented * Serializable (DG); * 21-Oct-2003 : Added hashCode() method, and new constructor for * convenience (DG); * 30-Sep-2004 : Replaced getTime().getTime() with getTimeInMillis() (DG); * 04-Nov-2004 : Reverted change of 30-Sep-2004, because it won't work for * JDK 1.3 (DG); * ------------- JFREECHART 1.0.x --------------------------------------------- * 05-Oct-2006 : Updated API docs (DG); * 06-Oct-2006 : Refactored to cache first and last millisecond values (DG); * 04-Apr-2007 : In Hour(Date, TimeZone), peg milliseconds using specified * time zone (DG); * 16-Sep-2008 : Deprecated DEFAULT_TIME_ZONE (DG); * 02-Mar-2009 : Added new constructor with Locale (DG); * 05-Jul-2012 : Replaced getTime().getTime() with getTimeInMillis() (DG); * 03-Jul-2013 : Use ParamChecks (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; import org.jfree.chart.util.ParamChecks; /** * Represents an hour in a specific day. This class is immutable, which is a * requirement for all {@link RegularTimePeriod} subclasses. */ public class Hour extends RegularTimePeriod implements Serializable { /** For serialization. */ private static final long serialVersionUID = -835471579831937652L; /** Useful constant for the first hour in the day. */ public static final int FIRST_HOUR_IN_DAY = 0; /** Useful constant for the last hour in the day. */ public static final int LAST_HOUR_IN_DAY = 23; /** The day. */ private Day day; /** The hour. */ private byte hour; /** The first millisecond. */ private long firstMillisecond; /** The last millisecond. */ private long lastMillisecond; /** * Constructs a new Hour, based on the system date/time. */ public Hour() { this(new Date()); } /** * Constructs a new Hour. * * @param hour the hour (in the range 0 to 23). * @param day the day (<code>null</code> not permitted). */ public Hour(int hour, Day day) { ParamChecks.nullNotPermitted(day, "day"); this.hour = (byte) hour; this.day = day; peg(Calendar.getInstance()); } /** * Creates a new hour. * * @param hour the hour (0-23). * @param day the day (1-31). * @param month the month (1-12). * @param year the year (1900-9999). */ public Hour(int hour, int day, int month, int year) { this(hour, new Day(day, month, year)); } /** * Constructs a new instance, based on the supplied date/time and * the default time zone. * * @param time the date-time (<code>null</code> not permitted). * * @see #Hour(Date, TimeZone) */ public Hour(Date time) { // defer argument checking... this(time, TimeZone.getDefault(), Locale.getDefault()); } /** * Constructs a new instance, based on the supplied date/time evaluated * in the specified time zone. * * @param time the date-time (<code>null</code> not permitted). * @param zone the time zone (<code>null</code> not permitted). * * @deprecated As of 1.0.13, use the constructor that specifies the locale * also. */ public Hour(Date time, TimeZone zone) { this(time, zone, Locale.getDefault()); } /** * Constructs a new instance, based on the supplied date/time evaluated * in the specified time zone. * * @param time the date-time (<code>null</code> not permitted). * @param zone the time zone (<code>null</code> not permitted). * @param locale the locale (<code>null</code> not permitted). * * @since 1.0.13 */ public Hour(Date time, TimeZone zone, Locale locale) { ParamChecks.nullNotPermitted(time, "time"); ParamChecks.nullNotPermitted(zone, "zone"); ParamChecks.nullNotPermitted(locale, "locale"); Calendar calendar = Calendar.getInstance(zone, locale); calendar.setTime(time); this.hour = (byte) calendar.get(Calendar.HOUR_OF_DAY); this.day = new Day(time, zone, locale); peg(calendar); } /** * Returns the hour. * * @return The hour (0 <= hour <= 23). */ public int getHour() { return this.hour; } /** * Returns the day in which this hour falls. * * @return The day. */ public Day getDay() { return this.day; } /** * Returns the year in which this hour falls. * * @return The year. */ public int getYear() { return this.day.getYear(); } /** * Returns the month in which this hour falls. * * @return The month. */ public int getMonth() { return this.day.getMonth(); } /** * Returns the day-of-the-month in which this hour falls. * * @return The day-of-the-month. */ public int getDayOfMonth() { return this.day.getDayOfMonth(); } /** * Returns the first millisecond of the hour. 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 hour. * * @see #getLastMillisecond() */ @Override public long getFirstMillisecond() { return this.firstMillisecond; } /** * Returns the last millisecond of the hour. 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 hour. * * @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 hour preceding this one. * * @return The hour preceding this one. */ @Override public RegularTimePeriod previous() { Hour result; if (this.hour != FIRST_HOUR_IN_DAY) { result = new Hour(this.hour - 1, this.day); } else { // we are at the first hour in the day... Day prevDay = (Day) this.day.previous(); if (prevDay != null) { result = new Hour(LAST_HOUR_IN_DAY, prevDay); } else { result = null; } } return result; } /** * Returns the hour following this one. * * @return The hour following this one. */ @Override public RegularTimePeriod next() { Hour result; if (this.hour != LAST_HOUR_IN_DAY) { result = new Hour(this.hour + 1, this.day); } else { // we are at the last hour in the day... Day nextDay = (Day) this.day.next(); if (nextDay != null) { result = new Hour(FIRST_HOUR_IN_DAY, nextDay); } else { result = null; } } return result; } /** * Returns a serial index number for the hour. * * @return The serial index number. */ @Override public long getSerialIndex() { return this.day.getSerialIndex() * 24L + this.hour; } /** * Returns the first millisecond of the hour. * * @param calendar the calendar/timezone (<code>null</code> not permitted). * * @return The first millisecond. * * @throws NullPointerException if <code>calendar</code> is * <code>null</code>. */ @Override public long getFirstMillisecond(Calendar calendar) { int year = this.day.getYear(); int month = this.day.getMonth() - 1; int dom = this.day.getDayOfMonth(); calendar.set(year, month, dom, this.hour, 0, 0); calendar.set(Calendar.MILLISECOND, 0); return calendar.getTimeInMillis(); } /** * Returns the last millisecond of the hour. * * @param calendar the calendar/timezone (<code>null</code> not permitted). * * @return The last millisecond. * * @throws NullPointerException if <code>calendar</code> is * <code>null</code>. */ @Override public long getLastMillisecond(Calendar calendar) { int year = this.day.getYear(); int month = this.day.getMonth() - 1; int dom = this.day.getDayOfMonth(); calendar.set(year, month, dom, this.hour, 59, 59); calendar.set(Calendar.MILLISECOND, 999); return calendar.getTimeInMillis(); } /** * Tests the equality of this object against an arbitrary Object. * <P> * This method will return true ONLY if the object is an Hour object * representing the same hour as this instance. * * @param obj the object to compare (<code>null</code> permitted). * * @return <code>true</code> if the hour and day value of the object * is the same as this. */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof Hour)) { return false; } Hour that = (Hour) obj; if (this.hour != that.hour) { return false; } if (!this.day.equals(that.day)) { return false; } return true; } /** * Returns a string representation of this instance, for debugging * purposes. * * @return A string. */ @Override public String toString() { return "[" + this.hour + "," + getDayOfMonth() + "/" + getMonth() + "/" + getYear() + "]"; } /** * 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; result = 37 * result + this.hour; result = 37 * result + this.day.hashCode(); return result; } /** * Returns an integer indicating the order of this Hour 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 Hour object // ----------------------------------------- if (o1 instanceof Hour) { Hour h = (Hour) o1; result = getDay().compareTo(h.getDay()); if (result == 0) { result = this.hour - h.getHour(); } } // 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; } /** * Creates an Hour instance by parsing a string. The string is assumed to * be in the format "YYYY-MM-DD HH", perhaps with leading or trailing * whitespace. * * @param s the hour string to parse. * * @return <code>null</code> if the string is not parseable, the hour * otherwise. */ public static Hour parseHour(String s) { Hour result = null; s = s.trim(); String daystr = s.substring(0, Math.min(10, s.length())); Day day = Day.parseDay(daystr); if (day != null) { String hourstr = s.substring(Math.min(daystr.length() + 1, s.length()), s.length()); hourstr = hourstr.trim(); int hour = Integer.parseInt(hourstr); // if the hour is 0 - 23 then create an hour if ((hour >= FIRST_HOUR_IN_DAY) && (hour <= LAST_HOUR_IN_DAY)) { result = new Hour(hour, day); } } return result; } }