/* ===========================================================
* JFreeChart : a free chart library for the Java(tm) platform
* ===========================================================
*
* (C) Copyright 2000-2007, 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.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* ----------------------
* RegularTimePeriod.java
* ----------------------
* (C) Copyright 2001-2007, 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);
*
*/
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.
*/
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()
*/
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()
*/
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,/code> is
* </code>null</code>.
*
* @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 a string representation of the time period.
*
* @return The string.
*/
public String toString() {
return String.valueOf(getStart());
}
}
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