gate.creole.annic.apache.lucene.document
Class DateField

java.lang.Object
  gate.creole.annic.apache.lucene.document.DateField

public class DateField
extends Object

Provides support for converting dates to strings and vice-versa. The strings are structured so that lexicographic sorting orders by date, which makes them suitable for use as field values and search terms.

Note that you do not have to use this class, you can just save your dates as strings if lexicographic sorting orders them by date. This is the case for example for dates like yyyy-mm-dd hh:mm:ss (of course you can leave out the delimiter characters to save some space). The advantage with using such a format is that you can easily save dates with the required granularity, e.g. leaving out seconds. This saves memory when searching with a RangeQuery or PrefixQuery, as Lucene expands these queries to a BooleanQuery with potentially very many terms.

Note: dates before 1970 cannot be used, and therefore cannot be indexed when using this class.

Method Summary

static String	dateToString(Date date) Converts a Date to a string suitable for indexing.
static String	MAX_DATE_STRING()
static String	MIN_DATE_STRING()
static Date	stringToDate(String s) Converts a string-encoded date into a Date object.
static long	stringToTime(String s) Converts a string-encoded date into a millisecond time.
static String	timeToString(long time) Converts a millisecond time to a string suitable for indexing.

Methods inherited from class java.lang.Object

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

Method Detail

MIN_DATE_STRING

public static String MIN_DATE_STRING()

MAX_DATE_STRING

public static String MAX_DATE_STRING()

dateToString

public static String dateToString(Date date)

Converts a Date to a string suitable for indexing.

Throws:

RuntimeException - if the date specified in the method argument is before 1970

timeToString

public static String timeToString(long time)

Converts a millisecond time to a string suitable for indexing.

Throws:

RuntimeException - if the time specified in the method argument is negative, that is, before 1970

stringToTime

public static long stringToTime(String s)

Converts a string-encoded date into a millisecond time.

stringToDate

public static Date stringToDate(String s)

Converts a string-encoded date into a Date object.