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.] * * ---------- * Month.java * ---------- * (C) Copyright 2001-2014, by Object Refinery Limited and Contributors. * * Original Author: David Gilbert (for Object Refinery Limited); * Contributor(s): Chris Boek; * * Changes * ------- * 11-Oct-2001 : Version 1 (DG); * 14-Nov-2001 : Added method to get year as primitive (DG); * Override for toString() method (DG); * 18-Dec-2001 : Changed order of parameters in constructor (DG); * 19-Dec-2001 : Added a new constructor as suggested by Paul English (DG); * 29-Jan-2002 : Worked on the parseMonth() method (DG); * 14-Feb-2002 : Fixed bugs in the Month constructors (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); * 13-Mar-2003 : Moved to com.jrefinery.data.time package, and implemented * Serializable (DG); * 21-Oct-2003 : Added hashCode() method (DG); * 01-Nov-2005 : Fixed bug 1345383 (argument check in constructor) (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 : Fixed bug in Month(Date, TimeZone) constructor (CB); * 01-Sep-2008 : Added clarification for previous() and next() methods (DG); * 16-Sep-2008 : Deprecated DEFAULT_TIME_ZONE, and updated parsing to handle * extended range in Year (DG); * 25-Nov-2008 : Added new constructor with Locale (DG); * 04-Feb-2009 : Fix for new constructor with Locale - bug 2564636 (DG); * */ package org.jfree.data.time; import org.jfree.chart.date.MonthConstants; import org.jfree.chart.date.SerialDate; import java.io.Serializable; import java.util.Calendar; import java.util.Date; import java.util.Locale; import java.util.TimeZone; /** * Represents a single month. This class is immutable, which is a requirement * for all {@link RegularTimePeriod} subclasses. */ public class Month extends RegularTimePeriod implements Serializable { /** For serialization. */ private static final long serialVersionUID = -5090216912548722570L; /** The month (1-12). */ private int month; /** The year in which the month falls. */ private int year; /** The first millisecond. */ private long firstMillisecond; /** The last millisecond. */ private long lastMillisecond; /** * Constructs a new Month, based on the current system time. */ public Month() { this(new Date()); } /** * Constructs a new month instance. * * @param month the month (in the range 1 to 12). * @param year the year. */ public Month(int month, int year) { if ((month < 1) || (month > 12)) { throw new IllegalArgumentException("Month outside valid range."); } this.month = month; this.year = year; peg(Calendar.getInstance()); } /** * Constructs a new month instance. * * @param month the month (in the range 1 to 12). * @param year the year. */ public Month(int month, Year year) { if ((month < 1) || (month > 12)) { throw new IllegalArgumentException("Month outside valid range."); } this.month = month; this.year = year.getYear(); peg(Calendar.getInstance()); } /** * Constructs a new <code>Month</code> instance, based on a date/time and * the default time zone. * * @param time the date/time (<code>null</code> not permitted). * * @see #Month(Date, TimeZone, Locale) */ public Month(Date time) { this(time, TimeZone.getDefault(), Locale.getDefault()); } /** * Creates a new <code>Month</code> instance, based on the specified time, * zone and locale. * * @param time the current time. * @param zone the time zone. * @param locale the locale. * * @since 1.0.12 */ public Month(Date time, TimeZone zone, Locale locale) { Calendar calendar = Calendar.getInstance(zone, locale); calendar.setTime(time); this.month = calendar.get(Calendar.MONTH) + 1; this.year = calendar.get(Calendar.YEAR); peg(calendar); } /** * Returns the year in which the month falls. * * @return The year in which the month falls (as a Year object). */ public Year getYear() { return new Year(this.year); } /** * Returns the year in which the month falls. * * @return The year in which the month falls (as an int). */ public int getYearValue() { return this.year; } /** * Returns the month. Note that 1=JAN, 2=FEB, ... * * @return The month. */ public int getMonth() { return this.month; } /** * Returns the first millisecond of the month. 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 month. * * @see #getLastMillisecond() */ @Override public long getFirstMillisecond() { return this.firstMillisecond; } /** * Returns the last millisecond of the month. 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 month. * * @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 month preceding this one. Note that the returned * {@link Month} is "pegged" using the default time-zone, irrespective of * the time-zone used to peg of the current month (which is not recorded * anywhere). See the {@link #peg(Calendar)} method. * * @return The month preceding this one. */ @Override public RegularTimePeriod previous() { Month result; if (this.month != MonthConstants.JANUARY) { result = new Month(this.month - 1, this.year); } else { if (this.year > 1900) { result = new Month(MonthConstants.DECEMBER, this.year - 1); } else { result = null; } } return result; } /** * Returns the month following this one. Note that the returned * {@link Month} is "pegged" using the default time-zone, irrespective of * the time-zone used to peg of the current month (which is not recorded * anywhere). See the {@link #peg(Calendar)} method. * * @return The month following this one. */ @Override public RegularTimePeriod next() { Month result; if (this.month != MonthConstants.DECEMBER) { result = new Month(this.month + 1, this.year); } else { if (this.year < 9999) { result = new Month(MonthConstants.JANUARY, this.year + 1); } else { result = null; } } return result; } /** * Returns a serial index number for the month. * * @return The serial index number. */ @Override public long getSerialIndex() { return this.year * 12L + this.month; } /** * Returns a string representing the month (e.g. "January 2002"). * <P> * To do: look at internationalisation. * * @return A string representing the month. */ @Override public String toString() { return SerialDate.monthCodeToString(this.month) + " " + this.year; } /** * Tests the equality of this Month object to an arbitrary object. * Returns true if the target is a Month instance representing the same * month as this object. In all other cases, returns false. * * @param obj the object (<code>null</code> permitted). * * @return <code>true</code> if month and year of this and object are the * same. */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof Month)) { return false; } Month that = (Month) obj; if (this.month != that.month) { return false; } if (this.year != that.year) { return false; } return true; } /** * 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.month; result = 37 * result + this.year; return result; } /** * Returns an integer indicating the order of this Month 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(TimePeriod o1) { int result; // CASE 1 : Comparing to another Month object // -------------------------------------------- if (o1 instanceof Month) { Month m = (Month) o1; result = this.year - m.getYearValue(); if (result == 0) { result = this.month - m.getMonth(); } } // CASE 2 : Comparing to another TimePeriod object // ----------------------------------------------- else { // more difficult case - evaluate later... result = 0; } return result; } /** * Returns the first millisecond of the month, 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 month. * * @throws NullPointerException if {@code calendar} is {@code null}. */ @Override public long getFirstMillisecond(Calendar calendar) { calendar.set(this.year, this.month - 1, 1, 0, 0, 0); calendar.set(Calendar.MILLISECOND, 0); return calendar.getTimeInMillis(); } /** * Returns the last millisecond of the month, 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 month. * * @throws NullPointerException if {@code calendar} is {@code null}. */ @Override public long getLastMillisecond(Calendar calendar) { int eom = SerialDate.lastDayOfMonth(this.month, this.year); calendar.set(this.year, this.month - 1, eom, 23, 59, 59); calendar.set(Calendar.MILLISECOND, 999); return calendar.getTimeInMillis(); } /** * Parses the string argument as a month. This method is required to * accept the format "YYYY-MM". It will also accept "MM-YYYY". Anything * else, at the moment, is a bonus. * * @param s the string to parse (<code>null</code> permitted). * * @return <code>null</code> if the string is not parseable, the month * otherwise. */ public static Month parseMonth(String s) { Month result = null; if (s == null) { return result; } // trim whitespace from either end of the string s = s.trim(); int i = Month.findSeparator(s); String s1, s2; boolean yearIsFirst; // if there is no separator, we assume the first four characters // are YYYY if (i == -1) { yearIsFirst = true; s1 = s.substring(0, 5); s2 = s.substring(5); } else { s1 = s.substring(0, i).trim(); s2 = s.substring(i + 1, s.length()).trim(); // now it is trickier to determine if the month or year is first Year y1 = Month.evaluateAsYear(s1); if (y1 == null) { yearIsFirst = false; } else { Year y2 = Month.evaluateAsYear(s2); if (y2 == null) { yearIsFirst = true; } else { yearIsFirst = (s1.length() > s2.length()); } } } Year year; int month; if (yearIsFirst) { year = Month.evaluateAsYear(s1); month = SerialDate.stringToMonthCode(s2); } else { year = Month.evaluateAsYear(s2); month = SerialDate.stringToMonthCode(s1); } if (month == -1) { throw new TimePeriodFormatException("Can't evaluate the month."); } if (year == null) { throw new TimePeriodFormatException("Can't evaluate the year."); } result = new Month(month, year); return result; } /** * Finds the first occurrence of '-', or if that character is not found, * the first occurrence of ',', or the first occurrence of ' ' or '.' * * @param s the string to parse. * * @return The position of the separator character, or <code>-1</code> if * none of the characters were found. */ private static int findSeparator(String s) { int result = s.indexOf('-'); if (result == -1) { result = s.indexOf(','); } if (result == -1) { result = s.indexOf(' '); } if (result == -1) { result = s.indexOf('.'); } return result; } /** * Creates a year from a string, or returns <code>null</code> (format * exceptions suppressed). * * @param s the string to parse. * * @return <code>null</code> if the string is not parseable, the year * otherwise. */ private static Year evaluateAsYear(String s) { Year result = null; try { result = Year.parseYear(s); } catch (TimePeriodFormatException e) { // suppress } return result; } }