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.] * * -------- * Day.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); * 15-Nov-2001 : Updated Javadoc comments (DG); * 04-Dec-2001 : Added static method to parse a string into a Day object (DG); * 19-Dec-2001 : Added new constructor as suggested by Paul English (DG); * 29-Jan-2002 : Changed getDay() method to getSerialDate() (DG); * 26-Feb-2002 : Changed getStart(), getMiddle() and getEnd() methods to * evaluate with reference to a particular time zone (DG); * 19-Mar-2002 : Changed the API for the TimePeriod classes (DG); * 29-May-2002 : Fixed bug in equals method (DG); * 24-Jun-2002 : Removed unnecessary imports (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 (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); * 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.text.DateFormat; import java.text.ParseException; import java.text.SimpleDateFormat; import java.util.Calendar; import java.util.Date; import java.util.Locale; import java.util.TimeZone; import org.jfree.chart.util.ParamChecks; import org.jfree.date.SerialDate; /** * Represents a single day in the range 1-Jan-1900 to 31-Dec-9999. This class * is immutable, which is a requirement for all {@link RegularTimePeriod} * subclasses. */ public class Day extends RegularTimePeriod implements Serializable { /** For serialization. */ private static final long serialVersionUID = -7082667380758962755L; /** A standard date formatter. */ protected static final DateFormat DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd"); /** A date formatter for the default locale. */ protected static final DateFormat DATE_FORMAT_SHORT = DateFormat.getDateInstance(DateFormat.SHORT); /** A date formatter for the default locale. */ protected static final DateFormat DATE_FORMAT_MEDIUM = DateFormat.getDateInstance(DateFormat.MEDIUM); /** A date formatter for the default locale. */ protected static final DateFormat DATE_FORMAT_LONG = DateFormat.getDateInstance(DateFormat.LONG); /** The day (uses SerialDate for convenience). */ private SerialDate serialDate; /** The first millisecond. */ private long firstMillisecond; /** The last millisecond. */ private long lastMillisecond; /** * Creates a new instance, derived from the system date/time (and assuming * the default timezone). */ public Day() { this(new Date()); } /** * Constructs a new one day time period. * * @param day the day-of-the-month. * @param month the month (1 to 12). * @param year the year (1900 <= year <= 9999). */ public Day(int day, int month, int year) { this.serialDate = SerialDate.createInstance(day, month, year); peg(Calendar.getInstance()); } /** * Constructs a new one day time period. * * @param serialDate the day (<code>null</code> not permitted). */ public Day(SerialDate serialDate) { ParamChecks.nullNotPermitted(serialDate, "serialDate"); this.serialDate = serialDate; peg(Calendar.getInstance()); } /** * Constructs a new instance, based on a particular date/time and the * default time zone. * * @param time the time (<code>null</code> not permitted). * * @see #Day(Date, TimeZone) */ public Day(Date time) { // defer argument checking... this(time, TimeZone.getDefault(), Locale.getDefault()); } /** * Constructs a new instance, based on a particular date/time and time zone. * * @param time the date/time. * @param zone the time zone. * * @deprecated As of 1.0.13, use the constructor that specifies the locale * also. */ public Day(Date time, TimeZone zone) { this(time, zone, Locale.getDefault()); } /** * Constructs a new instance, based on a particular date/time and 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). */ public Day(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); int d = calendar.get(Calendar.DAY_OF_MONTH); int m = calendar.get(Calendar.MONTH) + 1; int y = calendar.get(Calendar.YEAR); this.serialDate = SerialDate.createInstance(d, m, y); peg(calendar); } /** * Returns the day as a {@link SerialDate}. Note: the reference that is * returned should be an instance of an immutable {@link SerialDate} * (otherwise the caller could use the reference to alter the state of * this <code>Day</code> instance, and <code>Day</code> is supposed * to be immutable). * * @return The day as a {@link SerialDate}. */ public SerialDate getSerialDate() { return this.serialDate; } /** * Returns the year. * * @return The year. */ public int getYear() { return this.serialDate.getYYYY(); } /** * Returns the month. * * @return The month. */ public int getMonth() { return this.serialDate.getMonth(); } /** * Returns the day of the month. * * @return The day of the month. */ public int getDayOfMonth() { return this.serialDate.getDayOfMonth(); } /** * Returns the first millisecond of the day. 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 day. * * @see #getLastMillisecond() */ @Override public long getFirstMillisecond() { return this.firstMillisecond; } /** * Returns the last millisecond of the day. 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 day. * * @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 day preceding this one. * * @return The day preceding this one. */ @Override public RegularTimePeriod previous() { Day result; int serial = this.serialDate.toSerial(); if (serial > SerialDate.SERIAL_LOWER_BOUND) { SerialDate yesterday = SerialDate.createInstance(serial - 1); return new Day(yesterday); } else { result = null; } return result; } /** * Returns the day following this one, or <code>null</code> if some limit * has been reached. * * @return The day following this one, or <code>null</code> if some limit * has been reached. */ @Override public RegularTimePeriod next() { Day result; int serial = this.serialDate.toSerial(); if (serial < SerialDate.SERIAL_UPPER_BOUND) { SerialDate tomorrow = SerialDate.createInstance(serial + 1); return new Day(tomorrow); } else { result = null; } return result; } /** * Returns a serial index number for the day. * * @return The serial index number. */ @Override public long getSerialIndex() { return this.serialDate.toSerial(); } /** * Returns the first millisecond of the day, evaluated using the supplied * calendar (which determines the time zone). * * @param calendar calendar to use (<code>null</code> not permitted). * * @return The start of the day as milliseconds since 01-01-1970. * * @throws NullPointerException if <code>calendar</code> is * <code>null</code>. */ @Override public long getFirstMillisecond(Calendar calendar) { int year = this.serialDate.getYYYY(); int month = this.serialDate.getMonth(); int day = this.serialDate.getDayOfMonth(); calendar.clear(); calendar.set(year, month - 1, day, 0, 0, 0); calendar.set(Calendar.MILLISECOND, 0); return calendar.getTimeInMillis(); } /** * Returns the last millisecond of the day, evaluated using the supplied * calendar (which determines the time zone). * * @param calendar calendar to use (<code>null</code> not permitted). * * @return The end of the day as milliseconds since 01-01-1970. * * @throws NullPointerException if <code>calendar</code> is * <code>null</code>. */ @Override public long getLastMillisecond(Calendar calendar) { int year = this.serialDate.getYYYY(); int month = this.serialDate.getMonth(); int day = this.serialDate.getDayOfMonth(); calendar.clear(); calendar.set(year, month - 1, day, 23, 59, 59); calendar.set(Calendar.MILLISECOND, 999); return calendar.getTimeInMillis(); } /** * Tests the equality of this Day object to an arbitrary object. Returns * true if the target is a Day instance or a SerialDate instance * representing the same day as this object. In all other cases, * returns false. * * @param obj the object (<code>null</code> permitted). * * @return A flag indicating whether or not an object is equal to this day. */ @Override public boolean equals(Object obj) { if (obj == this) { return true; } if (!(obj instanceof Day)) { return false; } Day that = (Day) obj; if (!this.serialDate.equals(that.getSerialDate())) { 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() { return this.serialDate.hashCode(); } /** * Returns an integer indicating the order of this Day 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 Day object // ---------------------------------------- if (o1 instanceof Day) { Day d = (Day) o1; result = -d.getSerialDate().compare(this.serialDate); } // 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 day. * * @return A string representing the day. */ @Override public String toString() { return this.serialDate.toString(); } /** * Parses the string argument as a day. * <P> * This method is required to recognise YYYY-MM-DD as a valid format. * Anything else, for now, is a bonus. * * @param s the date string to parse. * * @return <code>null</code> if the string does not contain any parseable * string, the day otherwise. */ public static Day parseDay(String s) { try { return new Day(Day.DATE_FORMAT.parse(s)); } catch (ParseException e1) { try { return new Day(Day.DATE_FORMAT_SHORT.parse(s)); } catch (ParseException e2) { // ignore } } return null; } }