loci.poi.hssf.usermodel

Class HSSFDateUtil

java.lang.Object

loci.poi.hssf.usermodel.HSSFDateUtil

public class HSSFDateUtil
extends Object

Contains methods for dealing with Excel dates.

Author:

Michael Harhen, Glen Stampoultzis (glens at apache.org), Dan Sherman (dsherman at isisph.com), Hack Kampbjorn (hak at 2mba.dk)

Field Summary

Fields

Modifier and Type	Field and Description
private static int	BAD_DATE
private static long	DAY_MILLISECONDS

Constructor Summary

Constructors

Modifier	Constructor and Description
private	HSSFDateUtil()

Method Summary

Methods

Modifier and Type	Method and Description
private static int	absoluteDay(Calendar cal) Given a Calendar, return the number of days since 1900/12/31.
private static int	daysInPriorYears(int yr) Return the number of days in prior years since 1900
private static Calendar	dayStart(Calendar cal)
static double	getExcelDate(Date date) Given a Date, converts it into a double representing its internal Excel representation, which is the number of days since 1/1/1900.
static Date	getJavaDate(double date) Given a excel date, converts it into a Date.
static Date	getJavaDate(double date, boolean use1904windowing) Given an Excel date with either 1900 or 1904 date windowing, converts it to a java.util.Date.
static boolean	isADateFormat(int formatIndex, String formatString) Given a format ID and its format String, will check to see if the format represents a date format or not.
static boolean	isCellDateFormatted(HSSFCell cell) Check if a cell contains a date Since dates are stored internally in Excel as double values we infer it is a date if it is formatted as such.
static boolean	isCellInternalDateFormatted(HSSFCell cell) Check if a cell contains a date, checking only for internal excel date formats.
static boolean	isInternalDateFormat(int format) Given a format ID this will check whether the format represents an internal excel date format or not.
static boolean	isValidExcelDate(double value) Given a double, checks if it is a valid Excel date.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

BAD_DATE

private static final int BAD_DATE

See Also:

Constant Field Values

DAY_MILLISECONDS

private static final long DAY_MILLISECONDS

See Also:

Constant Field Values

Constructor Detail

HSSFDateUtil

private HSSFDateUtil()

Method Detail

getExcelDate

public static double getExcelDate(Date date)

Given a Date, converts it into a double representing its internal Excel representation, which is the number of days since 1/1/1900. Fractional days represent hours, minutes, and seconds.

Parameters:

date - the Date

Returns:

Excel representation of Date (-1 if error - test for error by checking for less than 0.1)

getJavaDate

public static Date getJavaDate(double date)

Given a excel date, converts it into a Date. Assumes 1900 date windowing.

Parameters:

date - the Excel Date

Returns:

Java representation of a date (null if error)

See Also:

getJavaDate(double,boolean)

getJavaDate

public static Date getJavaDate(double date,
               boolean use1904windowing)

Given an Excel date with either 1900 or 1904 date windowing, converts it to a java.util.Date. NOTE: If the default TimeZone in Java uses Daylight Saving Time then the conversion back to an Excel date may not give the same value, that is the comparison excelDate == getExcelDate(getJavaDate(excelDate,false)) is not always true. For example if default timezone is Europe/Copenhagen, on 2004-03-28 the minute after 01:59 CET is 03:00 CEST, if the excel date represents a time between 02:00 and 03:00 then it is converted to past 03:00 summer time

Parameters:

date - The Excel date.

use1904windowing - true if date uses 1904 windowing, or false if using 1900 date windowing.

Returns:

Java representation of the date, or null if date is not a valid Excel date

See Also:

TimeZone

isADateFormat

public static boolean isADateFormat(int formatIndex,
                    String formatString)

Given a format ID and its format String, will check to see if the format represents a date format or not. Firstly, it will check to see if the format ID corresponds to an internal excel date format (eg most US date formats) If not, it will check to see if the format string only contains date formatting characters (ymd-/), which covers most non US date formats.

Parameters:

formatIndex - The index of the format, eg from ExtendedFormatRecord.getFormatIndex

formatString - The format string, eg from FormatRecord.getFormatString

See Also:

isInternalDateFormat(int)

isInternalDateFormat

public static boolean isInternalDateFormat(int format)

Given a format ID this will check whether the format represents an internal excel date format or not.

See Also:

isADateFormat(int, java.lang.String)

isCellDateFormatted

public static boolean isCellDateFormatted(HSSFCell cell)

Check if a cell contains a date Since dates are stored internally in Excel as double values we infer it is a date if it is formatted as such.

See Also:

isADateFormat(int,String), isInternalDateFormat(int)

isCellInternalDateFormatted

public static boolean isCellInternalDateFormatted(HSSFCell cell)

Check if a cell contains a date, checking only for internal excel date formats. As Excel stores a great many of its dates in "non-internal" date formats, you will not normally want to use this method.

See Also:

isADateFormat(int,String), isInternalDateFormat(int)

isValidExcelDate

public static boolean isValidExcelDate(double value)

Given a double, checks if it is a valid Excel date.

Parameters:

value - the double value

Returns:

true if valid

absoluteDay

private static int absoluteDay(Calendar cal)

Given a Calendar, return the number of days since 1900/12/31.

Parameters:

cal - the Calendar

Returns:

days number of days since 1900/12/31

Throws:

IllegalArgumentException - if date is invalid

daysInPriorYears

private static int daysInPriorYears(int yr)

Return the number of days in prior years since 1900

Parameters:

yr - a year (1900 < yr < 4000)

Returns:

days number of days in years prior to yr.

Throws:

IllegalArgumentException - if year is outside of range.

dayStart

private static Calendar dayStart(Calendar cal)