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.] * * ---------------------- * RegularTimePeriod.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); * 26-Feb-2002 : Changed getStart(), getMiddle() and getEnd() methods to * evaluate with reference to a particular time zone (DG); * 29-May-2002 : Implemented MonthConstants interface, so that these constants * are conveniently available (DG); * 10-Sep-2002 : Added getSerialIndex() method (DG); * 10-Jan-2003 : Renamed TimePeriod --> RegularTimePeriod (DG); * 13-Mar-2003 : Moved to com.jrefinery.data.time package (DG); * 29-Apr-2004 : Changed getMiddleMillisecond() methods to fix bug 943985 (DG); * 25-Nov-2004 : Added utility methods (DG); * ------------- JFREECHART 1.0.x --------------------------------------------- * 06-Oct-2006 : Deprecated the WORKING_CALENDAR field and several methods, * added new peg() method (DG); * 16-Sep-2008 : Deprecated DEFAULT_TIME_ZONE (DG); * 23-Feb-2014 : Added getMillisecond() method (DG); * */ package org.jfree.data.time; import java.lang.reflect.Constructor; import java.util.Calendar; import java.util.Date; import java.util.TimeZone; import org.jfree.date.MonthConstants; /** * An abstract class representing a unit of time. Convenient methods are * provided for calculating the next and previous time periods. Conversion * methods are defined that return the first and last milliseconds of the time * period. The results from these methods are timezone dependent. * <P> * This class is immutable, and all subclasses should be immutable also. */ public abstract class RegularTimePeriod implements TimePeriod, Comparable, MonthConstants { /** * Creates a time period that includes the specified millisecond, assuming * the given time zone. * * @param c the time period class. * @param millisecond the time. * @param zone the time zone. * * @return The time period. */ public static RegularTimePeriod createInstance(Class c, Date millisecond, TimeZone zone) { RegularTimePeriod result = null; try { Constructor constructor = c.getDeclaredConstructor(new Class[] { Date.class, TimeZone.class }); result = (RegularTimePeriod) constructor.newInstance(new Object[] { millisecond, zone }); } catch (Exception e) { // do nothing, so null is returned } return result; } /** * Returns a subclass of {@link RegularTimePeriod} that is smaller than * the specified class. * * @param c a subclass of {@link RegularTimePeriod}. * * @return A class. */ public static Class downsize(Class c) { if (c.equals(Year.class)) { return Quarter.class; } else if (c.equals(Quarter.class)) { return Month.class; } else if (c.equals(Month.class)) { return Day.class; } else if (c.equals(Day.class)) { return Hour.class; } else if (c.equals(Hour.class)) { return Minute.class; } else if (c.equals(Minute.class)) { return Second.class; } else if (c.equals(Second.class)) { return Millisecond.class; } else { return Millisecond.class; } } /** * Returns the time period preceding this one, or <code>null</code> if some * lower limit has been reached. * * @return The previous time period (possibly <code>null</code>). */ public abstract RegularTimePeriod previous(); /** * Returns the time period following this one, or <code>null</code> if some * limit has been reached. * * @return The next time period (possibly <code>null</code>). */ public abstract RegularTimePeriod next(); /** * Returns a serial index number for the time unit. * * @return The serial index number. */ public abstract long getSerialIndex(); ////////////////////////////////////////////////////////////////////////// /** * The default time zone. * * @deprecated As of 1.0.11, we discourage the use of this field - use * {@link TimeZone#getDefault()} instead. */ public static final TimeZone DEFAULT_TIME_ZONE = TimeZone.getDefault(); /** * A working calendar (recycle to avoid unnecessary object creation). * * @deprecated This was a bad idea, don't use it! */ public static final Calendar WORKING_CALENDAR = Calendar.getInstance(DEFAULT_TIME_ZONE); /** * 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 */ public abstract void peg(Calendar calendar); /** * Returns the date/time that marks the start of the time period. This * method returns a new <code>Date</code> instance every time it is called. * * @return The start date/time. * * @see #getFirstMillisecond() */ @Override public Date getStart() { return new Date(getFirstMillisecond()); } /** * Returns the date/time that marks the end of the time period. This * method returns a new <code>Date</code> instance every time it is called. * * @return The end date/time. * * @see #getLastMillisecond() */ @Override public Date getEnd() { return new Date(getLastMillisecond()); } /** * Returns the first millisecond of the time period. 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 time period. * * @see #getLastMillisecond() */ public abstract long getFirstMillisecond(); /** * Returns the first millisecond of the time period, evaluated within a * specific time zone. * * @param zone the time zone (<code>null</code> not permitted). * * @return The first millisecond of the time period. * * @deprecated As of 1.0.3, you should avoid using this method (it creates * a new Calendar instance every time it is called). You are advised * to call {@link #getFirstMillisecond(Calendar)} instead. * * @see #getLastMillisecond(TimeZone) */ public long getFirstMillisecond(TimeZone zone) { Calendar calendar = Calendar.getInstance(zone); return getFirstMillisecond(calendar); } /** * Returns the first millisecond of the time period, evaluated using the * supplied calendar (which incorporates a timezone). * * @param calendar the calendar (<code>null</code> not permitted). * * @return The first millisecond of the time period. * * @throws NullPointerException if {@code calendar} is {@code null}. * * @see #getLastMillisecond(Calendar) */ public abstract long getFirstMillisecond(Calendar calendar); /** * Returns the last millisecond of the time period. 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 time period. * * @see #getFirstMillisecond() */ public abstract long getLastMillisecond(); /** * Returns the last millisecond of the time period, evaluated within a * specific time zone. * * @param zone the time zone (<code>null</code> not permitted). * * @return The last millisecond of the time period. * * @deprecated As of 1.0.3, you should avoid using this method (it creates * a new Calendar instance every time it is called). You are advised * to call {@link #getLastMillisecond(Calendar)} instead. * * @see #getFirstMillisecond(TimeZone) */ public long getLastMillisecond(TimeZone zone) { Calendar calendar = Calendar.getInstance(zone); return getLastMillisecond(calendar); } /** * Returns the last millisecond of the time period, evaluated using the * supplied calendar (which incorporates a timezone). * * @param calendar the calendar (<code>null</code> not permitted). * * @return The last millisecond of the time period. * * @see #getFirstMillisecond(Calendar) */ public abstract long getLastMillisecond(Calendar calendar); /** * Returns the millisecond closest to the middle of the time period. * * @return The middle millisecond. */ public long getMiddleMillisecond() { long m1 = getFirstMillisecond(); long m2 = getLastMillisecond(); return m1 + (m2 - m1) / 2; } /** * Returns the millisecond closest to the middle of the time period, * evaluated within a specific time zone. * * @param zone the time zone (<code>null</code> not permitted). * * @return The middle millisecond. * * @deprecated As of 1.0.3, you should avoid using this method (it creates * a new Calendar instance every time it is called). You are advised * to call {@link #getMiddleMillisecond(Calendar)} instead. */ public long getMiddleMillisecond(TimeZone zone) { Calendar calendar = Calendar.getInstance(zone); long m1 = getFirstMillisecond(calendar); long m2 = getLastMillisecond(calendar); return m1 + (m2 - m1) / 2; } /** * Returns the millisecond closest to the middle of the time period, * evaluated using the supplied calendar (which incorporates a timezone). * * @param calendar the calendar. * * @return The middle millisecond. */ public long getMiddleMillisecond(Calendar calendar) { long m1 = getFirstMillisecond(calendar); long m2 = getLastMillisecond(calendar); return m1 + (m2 - m1) / 2; } /** * Returns the millisecond (relative to the epoch) corresponding to the * specified <code>anchor</code> using the supplied <code>calendar</code> * (which incorporates a time zone). * * @param anchor the anchor (<code>null</code> not permitted). * @param calendar the calendar (<code>null</code> not permitted). * * @return Milliseconds since the epoch. * * @since 1.0.18 */ public long getMillisecond(TimePeriodAnchor anchor, Calendar calendar) { if (anchor.equals(TimePeriodAnchor.START)) { return getFirstMillisecond(calendar); } else if (anchor.equals(TimePeriodAnchor.MIDDLE)) { return getMiddleMillisecond(calendar); } else if (anchor.equals(TimePeriodAnchor.END)) { return getLastMillisecond(calendar); } else { throw new IllegalStateException("Unrecognised anchor: " + anchor); } } /** * Returns a string representation of the time period. * * @return The string. */ @Override public String toString() { return String.valueOf(getStart()); } }