java.util
Class Date

java.lang.Object
  |
  +--java.util.Date

public class Date

extends Object

The class Date represents a specific instant in time, with millisecond precision.

This Class has been subset for the MID Profile based on JDK 1.3. In the full API, the class Date had two additional functions. It allowed the interpretation of dates as year, month, day, hour, minute, and second values. It also allowed the formatting and parsing of date strings. Unfortunately, the API for these functions was not amenable to internationalization. As of JDK 1.1, the Calendar class should be used to convert between dates and time fields and the DateFormat class should be used to format and parse date strings. The corresponding methods in Date are deprecated.

Although the Date class is intended to reflect coordinated universal time (UTC), it may not do so exactly, depending on the host environment of the Java Virtual Machine. Nearly all modern operating systems assume that 1 day = 24x60x60 = 86400 seconds in all cases. In UTC, however, about once every year or two there is an extra second, called a "leap second." The leap second is always added as the last second of the day, and always on December 31 or June 30. For example, the last minute of the year 1995 was 61 seconds long, thanks to an added leap second. Most computer clocks are not accurate enough to be able to reflect the leap-second distinction.

See Also:

TimeZone, Calendar

Constructor Summary

Date()
Allocates a Date object and initializes it to represent the current time specified number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.

Date(long date)
Allocates a Date object and initializes it to represent the specified number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.

Method Summary

boolean	equals(Object obj) Compares two dates for equality.
long	getTime() Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this Date object.
int	hashCode() Returns a hash code value for this object.
void	setTime(long time) Sets this Date object to represent a point in time that is time milliseconds after January 1, 1970 00:00:00 GMT.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Date

public Date()

Allocates a Date object and initializes it to represent the current time specified number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.

See Also:

System.currentTimeMillis()

Date

public Date(long date)

Allocates a Date object and initializes it to represent the specified number of milliseconds since the standard base time known as "the epoch", namely January 1, 1970, 00:00:00 GMT.

Parameters:

date - the milliseconds since January 1, 1970, 00:00:00 GMT.

See Also:

System.currentTimeMillis()

Method Detail

getTime

public long getTime()

Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this Date object.

Returns:

the number of milliseconds since January 1, 1970, 00:00:00 GMT represented by this date.

See Also:

setTime(long)

setTime

public void setTime(long time)

Sets this Date object to represent a point in time that is time milliseconds after January 1, 1970 00:00:00 GMT.

Parameters:

time - the number of milliseconds.

See Also:

getTime()

equals

public boolean equals(Object obj)

Compares two dates for equality. The result is true if and only if the argument is not null and is a Date object that represents the same point in time, to the millisecond, as this object.

Thus, two Date objects are equal if and only if the getTime method returns the same long value for both.

Overrides:

equals in class Object

Parameters:

obj - the object to compare with.

Returns:

true if the objects are the same; false otherwise.

See Also:

getTime()

hashCode

public int hashCode()

Returns a hash code value for this object. The result is the exclusive OR of the two halves of the primitive long value returned by the getTime() method. That is, the hash code is the value of the expression:

 (int)(this.getTime()^(this.getTime() >>> 32))

Overrides:

hashCode in class Object

Returns:

a hash code value for this object.

See Also:

Object.equals(java.lang.Object), Hashtable