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DateFormat.java
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/*
* @(#)DateFormat.java 1.20 97/02/05
*
* (C) Copyright Taligent, Inc. 1996 - All Rights Reserved
* (C) Copyright IBM Corp. 1996 - All Rights Reserved
*
* Portions copyright (c) 1996 Sun Microsystems, Inc. All Rights Reserved.
*
* The original version of this source code and documentation is copyrighted
* and owned by Taligent, Inc., a wholly-owned subsidiary of IBM. These
* materials are provided under terms of a License Agreement between Taligent
* and Sun. This technology is protected by multiple US and International
* patents. This notice and attribution to Taligent may not be removed.
* Taligent is a registered trademark of Taligent, Inc.
*
* Permission to use, copy, modify, and distribute this software
* and its documentation for NON-COMMERCIAL purposes and without
* fee is hereby granted provided that this copyright notice
* appears in all copies. Please refer to the file "copyright.html"
* for further important copyright and licensing information.
*
* SUN MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
* THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
* TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
* PARTICULAR PURPOSE, OR NON-INFRINGEMENT. SUN SHALL NOT BE LIABLE FOR
* ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
* DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
*
*/
package java.text;
import java.util.Locale;
import java.util.ResourceBundle;
import java.util.MissingResourceException;
import java.util.TimeZone;
import java.util.SimpleTimeZone;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.Date;
import java.text.resources.*;
/**
* DateFormat is an abstract class for date/time formatting subclasses which
* formats and parses dates or time in a language-independent manner.
* The date/time formatting subclass, such as SimpleDateFormat, allows for
* formatting (i.e., millis -> text), parsing (text -> millis), and
* normalization. Formats/Parses a date or time, which is the standard millis
* since 24:00 GMT, Jan 1, 1970
*
* <p>DateFormat provides many class methods for obtaining default date/time
* formatters based on the default or a given loacle and a number of formatting
* styles. The formatting styles include FULL, LONG, MEDIUM, and SHORT. More
* detail and examples of using these styles are provided in the method
* descriptions.
*
* <p>DateFormat helps you to format and parse dates for any locale.
* Your code can be completely independent of the locale conventions for
* months, days of the week, or even the calendar format: lunar vs. solar.
*
* <p>To format a date for the current Locale, use one of the
* static factory methods:
* <pre>
* myString = DateFormat.getDateInstance().format(myDate);
* </pre>
* <p>If you are formatting multiple numbers, it is
* more efficient to get the format and use it multiple times so that
* the system doesn't have to fetch the information about the local
* language and country conventions multiple times.
* <pre>
* DateFormat df = DateFormat.getDateInstance();
* for (int i = 0; i < a.length; ++i) {
* output.println(df.format(myDate[i]) + "; ");
* }
* </pre>
* <p>To format a number for a different Locale, specify it in the
* call to getDateInstance().
* <pre>
* DateFormat df = DateFormat.getDateInstance(Locale.FRANCE);
* </pre>
* <p>You can use a DateFormat to parse also.
* <pre>
* myDate = df.parse(myString);
* </pre>
* <p>Use getDate to get the normal date format for that country.
* There are other static factory methods available.
* Use getTime to get the time format for that country.
* Use getDateTime to get a date and time format. You can pass in different
* options to these factory methods to control the length of the
* result; from SHORT to MEDIUM to LONG to FULL. The exact result depends
* on the locale, but generally:
* <ul><li>SHORT is completely numeric, such as 12.13.52 or 3:30pm
* <li>MEDIUM is longer, such as Jan 12, 1952
* <li>LONG is longer, such as January 12, 1952 or 3:30:32pm
* <li>FULL is pretty completely specified, such as
* Tuesday, April 12, 1952 AD or 3:30:42pm PST.
* </ul>
*
* <p>You can also set the time zone on the format if you wish.
* If you want even more control over the format or parsing,
* (or want to give your users more control),
* you can try casting the DateFormat you get from the factory methods
* to a SimpleDateFormat. This will work for the majority
* of countries; just remember to put it in a try block in case you
* encounter an unusual one.
*
* <p>You can also use forms of the parse and format methods with
* ParsePosition and FieldPosition to
* allow you to
* <ul><li>pregressively parse through pieces of a string.
* <li>align any particular field, or find out where it is for selection
* on the screen.
* </ul>
*
* @see Format
* @see NumberFormat
* @see SimpleDateFormat
* @see java.util.Calendar
* @see java.util.GregorianCalendar
* @see java.util.TimeZone
* @version 1.20 02/05/97
* @author Mark Davis, Chen-Lieh Huang
*/
public abstract class DateFormat extends Format implements Cloneable {
/**
* The calendar that DateFormat uses to produce the time field values
* needed to implement date/time formatting. Subclasses should initialize
* this to the default calendar for the locale associated with this
* DateFormat.
*/
protected Calendar calendar;
/**
* The number formatter that DateFormat uses to format numbers in dates
* and times. Subclasses should initialize this to the default number
* format for the locale associated with this DateFormat.
*/
protected NumberFormat numberFormat;
/**
* Useful constant for ERA field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int ERA_FIELD = 0;
/**
* Useful constant for YEAR field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int YEAR_FIELD = 1;
/**
* Useful constant for MONTH field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int MONTH_FIELD = 2;
/**
* Useful constant for DATE field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int DATE_FIELD = 3;
/**
* Useful constant for one-based HOUR_OF_DAY field alignment.
* Used in FieldPosition of date/time formatting.
* HOUR_OF_DAY1_FIELD is used for the one-based 24-hour clock.
* For example, 23:59 + 01:00 results in 24:59.
*/
public final static int HOUR_OF_DAY1_FIELD = 4;
/**
* Useful constant for zero-based HOUR_OF_DAY field alignment.
* Used in FieldPosition of date/time formatting.
* HOUR_OF_DAY0_FIELD is used for the zero-based 24-hour clock.
* For example, 23:59 + 01:00 results in 00:59.
*/
public final static int HOUR_OF_DAY0_FIELD = 5;
/**
* Useful constant for MINUTE field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int MINUTE_FIELD = 6;
/**
* Useful constant for SECOND field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int SECOND_FIELD = 7;
/**
* Useful constant for MILLISECOND field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int MILLISECOND_FIELD = 8;
/**
* Useful constant for DAY_OF_WEEK field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int DAY_OF_WEEK_FIELD = 9;
/**
* Useful constant for DAY_OF_YEAR field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int DAY_OF_YEAR_FIELD = 10;
/**
* Useful constant for DAY_OF_WEEK_IN_MONTH field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int DAY_OF_WEEK_IN_MONTH_FIELD = 11;
/**
* Useful constant for WEEK_OF_YEAR field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int WEEK_OF_YEAR_FIELD = 12;
/**
* Useful constant for WEEK_OF_MONTH field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int WEEK_OF_MONTH_FIELD = 13;
/**
* Useful constant for AM_PM field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int AM_PM_FIELD = 14;
/**
* Useful constant for one-based HOUR field alignment.
* Used in FieldPosition of date/time formatting.
* HOUR1_FIELD is used for the one-based 12-hour clock.
* For example, 11:30 PM + 1 hour results in 12:30 AM.
*/
public final static int HOUR1_FIELD = 15;
/**
* Useful constant for zero-based HOUR field alignment.
* Used in FieldPosition of date/time formatting.
* HOUR0_FIELD is used for the zero-based 12-hour clock.
* For example, 11:30 PM + 1 hour results in 00:30 AM.
*/
public final static int HOUR0_FIELD = 16;
/**
* Useful constant for TIMEZONE field alignment.
* Used in FieldPosition of date/time formatting.
*/
public final static int TIMEZONE_FIELD = 17;
/**
* Overrides Format.
* Formats a time object into a time string. Examples of time objects
* are a time value expressed in milliseconds and a Date object.
* @param obj must be a Number or a Date.
* @param toAppendTo the string buffer for the returning time string.
* @param status the formatting status. On input: an alignment field,
* if desired. On output: the offsets of the alignment field.
* @return the formatted time string.
* @see java.util.Format
*/
public final StringBuffer format(Object obj, StringBuffer toAppendTo,
FieldPosition fieldPosition)
{
if (obj instanceof Number)
return format( new Date(((Number)obj).longValue()),
toAppendTo, fieldPosition );
else if (obj instanceof Date)
return format( (Date)obj, toAppendTo, fieldPosition );
else
throw new IllegalArgumentException("Cannot format given Object as a Date");
}
/**
* Formats a Date into a date/time string.
* @param date a Date to be formatted into a date/time string.
* @param toAppendTo the string buffer for the returning date/time string.
* @param status the formatting status. On input: an alignment field,
* if desired. On output: the offsets of the alignment field. For
* example, given a time text "1996.07.10 AD at 15:08:56 PDT",
* if the given status.field is DateFormat.YEAR_FIELD, the offsets
* status.beginIndex and status.getEndIndex will be set to 0 and 4,
* respectively. Notice that if the same time field appears
* more than once in a pattern, the status will be set for the first
* occurence of that time field. For instance, formatting a Date to
* the time string "1 PM PDT (Pacific Daylight Time)" using the pattern
* "h a z (zzzz)" and the alignment field DateFormat.TIMEZONE_FIELD,
* the offsets status.beginIndex and status.getEndIndex will be set to
* 5 and 8, respectively, for the first occurence of the timezone
* pattern character 'z'.
* @return the formatted date/time string.
*/
public abstract StringBuffer format(Date date, StringBuffer toAppendTo,
FieldPosition fieldPosition);
/**
* Formats a Date into a date/time string.
* @param date the time value to be formatted into a time string.
* @return the formatted time string.
*/
public final String format(Date date)
{
return format(date, new StringBuffer(),new FieldPosition(0)).toString();
}
/**
* Parse a date/time string.
*
* @exception ParseException If the given string cannot be parsed as a date.
*
* @see #parse(String, ParsePosition)
*/
public Date parse(String text) throws ParseException
{
ParsePosition pos = new ParsePosition(0);
Date result = parse(text, pos);
if (pos.index == 0)
throw new ParseException("Unparseable date: \"" + text + "\"" , 0);
return result;
}
/**
* Parse a date/time string according to the given parse position. For
* example, a time text "07/10/96 4:5 PM, PDT" will be parsed into a Date
* that is equivalent to Date(837039928046).
*
* <p> By default, parsing is lenient: If the input is not in the form used
* by this object's format method but can still be parsed as a date, then
* the parse succeeds. Clients may insist on strict adherence to the
* format by calling setLenient(false).
*
* @see java.text.DateFormat#setLenient(boolean)
*
* @param text The date/time string to be parsed
*
* @param pos On input, the position at which to start parsing; on
* output, the position at which parsing terminated, or the
* start position if the parse failed.
*
* @return A Date, or null if the input could not be parsed
*/
public abstract Date parse(String text, ParsePosition pos);
/**
* Parse a date/time string into an Object. This convenience method simply
* calls parse(String, ParsePosition).
*
* @see #parse(String, ParsePosition)
*/
public Object parseObject (String source, ParsePosition pos)
{
return parse(source, pos);
}
/**
* Constant for full style pattern.
*/
public static final int FULL = 0;
/**
* Constant for long style pattern.
*/
public static final int LONG = 1;
/**
* Constant for medium style pattern.
*/
public static final int MEDIUM = 2;
/**
* Constant for short style pattern.
*/
public static final int SHORT = 3;
/**
* Constant for default style pattern.
*/
public static final int DEFAULT = MEDIUM;
/**
* Gets the time formatter with the default formatting style
* for the default locale.
* @return a time formatter.
*/
public final static DateFormat getTimeInstance()
{
return get(DEFAULT, -1, Locale.getDefault());
}
/**
* Gets the time formatter with the given formatting style
* for the default locale.
* @param style the given formatting style. For example,
* SHORT for "h:mm a" in the US locale.
* @return a time formatter.
*/
public final static DateFormat getTimeInstance(int style)
{
return get(style, -1, Locale.getDefault());
}
/**
* Gets the time formatter with the given formatting style
* for the given locale.
* @param style the given formatting style. For example,
* SHORT for "h:mm a" in the US locale.
* @param inLocale the given locale.
* @return a time formatter.
*/
public final static DateFormat getTimeInstance(int style,
Locale aLocale)
{
return get(style, -1, aLocale);
}
/**
* Gets the date formatter with the default formatting style
* for the default locale.
* @return a date formatter.
*/
public final static DateFormat getDateInstance()
{
// +4 to set the correct index for getting data out of
// LocaleElements.
return get(-1, DEFAULT + 4, Locale.getDefault());
}
/**
* Gets the date formatter with the given formatting style
* for the default locale.
* @param style the given formatting style. For example,
* SHORT for "M/d/yy" in the US locale.
* @return a date formatter.
*/
public final static DateFormat getDateInstance(int style)
{
return get(-1, style + 4, Locale.getDefault());
}
/**
* Gets the date formatter with the given formatting style
* for the given locale.
* @param style the given formatting style. For example,
* SHORT for "M/d/yy" in the US locale.
* @param inLocale the given locale.
* @return a date formatter.
*/
public final static DateFormat getDateInstance(int style,
Locale aLocale)
{
return get(-1, style + 4, aLocale);
}
/**
* Gets the date/time formatter with the default formatting style
* for the default locale.
* @return a date/time formatter.
*/
public final static DateFormat getDateTimeInstance()
{
return get(DEFAULT, DEFAULT + 4, Locale.getDefault());
}
/**
* Gets the date/time formatter with the given date and time
* formatting styles for the default locale.
* @param dateStyle the given date formatting style. For example,
* SHORT for "M/d/yy" in the US locale.
* @param timeStyle the given time formatting style. For example,
* SHORT for "h:mm a" in the US locale.
* @return a date/time formatter.
*/
public final static DateFormat getDateTimeInstance(int dateStyle,
int timeStyle)
{
return get(timeStyle, dateStyle + 4, Locale.getDefault());
}
/**
* Gets the date/time formatter with the given formatting styles
* for the given locale.
* @param dateStyle the given date formatting style.
* @param timeStyle the given time formatting style.
* @param inLocale the given locale.
* @return a date/time formatter.
*/
public final static DateFormat
getDateTimeInstance(int dateStyle, int timeStyle, Locale aLocale)
{
return get(timeStyle, dateStyle + 4, aLocale);
}
/**
* Get a default date/time formatter that uses the SHORT style for both the
* date and the time.
*/
public final static DateFormat getInstance() {
return getDateTimeInstance(SHORT, SHORT);
}
/**
* Gets the set of locales for which DateFormats are installed.
* @return the set of locales for which DateFormats are installed.
*/
public static Locale[] getAvailableLocales()
{
return LocaleData.getAvailableLocales("DateTimePatterns");
}
/**
* Set the calendar to be used by this date format. Initially, the default
* calendar for the specified or default locale is used.
*/
public void setCalendar(Calendar newCalendar)
{
this.calendar = newCalendar;
}
/**
* Gets the calendar associated with this date/time formatter.
* @return the calendar associated with this date/time formatter.
*/
public Calendar getCalendar()
{
return calendar;
}
/**
* Allows you to set the number formatter.
* @param newNumberFormat the given new NumberFormat.
*/
public void setNumberFormat(NumberFormat newNumberFormat)
{
this.numberFormat = newNumberFormat;
}
/**
* Gets the number formatter which this date/time formatter uses to
* format and parse a time.
* @return the number formatter which this date/time formatter uses.
*/
public NumberFormat getNumberFormat()
{
return numberFormat;
}
/**
* Sets the time zone for the calendar of this DateFormat object.
* @param zone the given new time zone.
*/
public void setTimeZone(TimeZone zone)
{
calendar.setTimeZone(zone);
}
/**
* Gets the time zone.
* @return the time zone associated with the calendar of DateFormat.
*/
public TimeZone getTimeZone()
{
return calendar.getTimeZone();
}
/**
* Specify whether or not date/time parsing is to be lenient. With
* lenient parsing, the parser may use heuristics to interpret inputs that
* do not precisely match this object's format. With strict parsing,
* inputs must match this object's format.
* @see java.util.Calendar#setLenient
*/
public void setLenient(boolean lenient)
{
calendar.setLenient(lenient);
}
/**
* Tell whether date/time parsing is to be lenient.
*/
public boolean isLenient()
{
return calendar.isLenient();
}
/**
* Overrides hashCode
*/
public int hashCode() {
return numberFormat.hashCode();
// just enough fields for a reasonable distribution
}
/**
* Overrides equals
*/
public boolean equals(Object obj) {
if (this == obj) return true;
if (getClass() != obj.getClass()) return false;
DateFormat other = (DateFormat) obj;
return (calendar.equals(other.calendar)
&& numberFormat.equals(other.numberFormat));
}
/**
* Overrides Cloneable
*/
public Object clone()
{
DateFormat other = (DateFormat) super.clone();
other.calendar = (Calendar) calendar.clone();
other.numberFormat = (NumberFormat) numberFormat.clone();
return other;
}
private static DateFormat get(int timeStyle, /* -1 for no time */
int dateStyle, /* -1 for no date */
Locale loc) {
try {
ResourceBundle resource
= ResourceBundle.getBundle
("java.text.resources.LocaleElements", loc);
return new SimpleDateFormat(timeStyle, dateStyle, loc);
} catch (MissingResourceException e) {
return new SimpleDateFormat("M/d/yy h:mm a");
}
}
protected DateFormat() { }
}