java.util.Date Maven / Gradle / Ivy
/*
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a platform that includes technologies expressed as Java APIs. The file
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Any work generated from this file, such as unified javadocs or compiled
stub files, must be accompanied by this notice in its entirety.
This work corresponds to the API signatures of JSR 219: Foundation
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JSR 219 specification, which is available at
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*/
package java.util;
import java.util.Calendar;
import java.util.GregorianCalendar;
import java.util.TimeZone;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.io.IOException;
import java.io.ObjectOutputStream;
import java.io.ObjectInputStream;
import java.lang.ref.SoftReference;
/**
* The class Date represents a specific instant
* in time, with millisecond precision.
*
* Prior to JDK 1.1, 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 =
* 24 × 60 × 60 = 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.
*
* Some computer standards are defined in terms of Greenwich mean
* time (GMT), which is equivalent to universal time (UT). GMT is
* the "civil" name for the standard; UT is the
* "scientific" name for the same standard. The
* distinction between UTC and UT is that UTC is based on an atomic
* clock and UT is based on astronomical observations, which for all
* practical purposes is an invisibly fine hair to split. Because the
* earth's rotation is not uniform (it slows down and speeds up
* in complicated ways), UT does not always flow uniformly. Leap
* seconds are introduced as needed into UTC so as to keep UTC within
* 0.9 seconds of UT1, which is a version of UT with certain
* corrections applied. There are other time and date systems as
* well; for example, the time scale used by the satellite-based
* global positioning system (GPS) is synchronized to UTC but is
* not adjusted for leap seconds. An interesting source of
* further information is the U.S. Naval Observatory, particularly
* the Directorate of Time at:
*
* http://tycho.usno.navy.mil
*
*
* and their definitions of "Systems of Time" at:
*
* http://tycho.usno.navy.mil/systime.html
*
*
* In all methods of class Date that accept or return
* year, month, date, hours, minutes, and seconds values, the
* following representations are used:
*
* - A year y is represented by the integer
* y
- 1900.
* - A month is represented by an integer from 0 to 11; 0 is January,
* 1 is February, and so forth; thus 11 is December.
*
- A date (day of month) is represented by an integer from 1 to 31
* in the usual manner.
*
- An hour is represented by an integer from 0 to 23. Thus, the hour
* from midnight to 1 a.m. is hour 0, and the hour from noon to 1
* p.m. is hour 12.
*
- A minute is represented by an integer from 0 to 59 in the usual manner.
*
- A second is represented by an integer from 0 to 61; the values 60 and
* 61 occur only for leap seconds and even then only in Java
* implementations that actually track leap seconds correctly. Because
* of the manner in which leap seconds are currently introduced, it is
* extremely unlikely that two leap seconds will occur in the same
* minute, but this specification follows the date and time conventions
* for ISO C.
*
*
* In all cases, arguments given to methods for these purposes need
* not fall within the indicated ranges; for example, a date may be
* specified as January 32 and is interpreted as meaning February 1.
*
* @author James Gosling
* @author Arthur van Hoff
* @author Alan Liu
* @version 1.70 11/09/00
* @see java.text.DateFormat
* @see java.util.Calendar
* @see java.util.TimeZone
* @since JDK1.0
*/
public class Date implements java.io.Serializable, Cloneable, Comparable
{
private static final long serialVersionUID = 7523967970034938905L;
/**
* Allocates a Date object and initializes it so that
* it represents the time at which it was allocated, measured to the
* nearest millisecond.
*
* @see java.lang.System#currentTimeMillis()
*/
public 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.
*
* @param date the milliseconds since January 1, 1970, 00:00:00 GMT.
* @see java.lang.System#currentTimeMillis()
*/
public Date(long date) { }
/**
* Return a copy of this object.
*/
public Object clone() {
return null;
}
/**
* Returns the number of milliseconds since January 1, 1970, 00:00:00 GMT
* represented by this Date object.
*
* @return the number of milliseconds since January 1, 1970, 00:00:00 GMT
* represented by this date.
*/
public long getTime() {
return -1;
}
/**
* Sets this Date object to represent a point in time that is
* time milliseconds after January 1, 1970 00:00:00 GMT.
*
* @param time the number of milliseconds.
*/
public void setTime(long time) { }
/**
* Tests if this date is before the specified date.
*
* @param when a date.
* @return true if and only if the instant of time
* represented by this Date object is strictly
* earlier than the instant represented by when;
* false otherwise.
*/
public boolean before(Date when) {
return false;
}
/**
* Tests if this date is after the specified date.
*
* @param when a date.
* @return true if and only if the instant represented
* by this Date object is strictly later than the
* instant represented by when;
* false otherwise.
*/
public boolean after(Date when) {
return false;
}
/**
* 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.
*
* @param obj the object to compare with.
* @return true if the objects are the same;
* false otherwise.
* @see java.util.Date#getTime()
*/
public boolean equals(Object obj) {
return false;
}
/**
* Compares two Dates for ordering.
*
* @param anotherDate the Date to be compared.
* @return the value 0 if the argument Date is equal to
* this Date; a value less than 0 if this Date
* is before the Date argument; and a value greater than
* 0 if this Date is after the Date argument.
* @since 1.2
*/
public int compareTo(Date anotherDate) {
return 0;
}
/**
* Compares this Date to another Object. If the Object is a Date,
* this function behaves like compareTo(Date). Otherwise,
* it throws a ClassCastException (as Dates are comparable
* only to other Dates).
*
* @param o the Object to be compared.
* @return the value 0 if the argument is a Date
* equal to this Date; a value less than 0 if the
* argument is a Date after this Date; and a value greater than
* 0 if the argument is a Date before this Date.
* @exception ClassCastException if the argument is not a
* Date.
* @see java.lang.Comparable
* @since 1.2
*/
public int compareTo(Object o) {
return 0;
}
/**
* 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 {@link Date#getTime}
* method. That is, the hash code is the value of the expression:
*
* (int)(this.getTime()^(this.getTime() >>> 32))
*
* @return a hash code value for this object.
*/
public int hashCode() {
return 0;
}
/**
* Converts this Date object to a String
* of the form:
*
* dow mon dd hh:mm:ss zzz yyyy
* where:
* - dow is the day of the week (Sun, Mon, Tue, Wed,
* Thu, Fri, Sat).
*
- mon is the month (Jan, Feb, Mar, Apr, May, Jun,
* Jul, Aug, Sep, Oct, Nov, Dec).
*
- dd is the day of the month (01 through
* 31), as two decimal digits.
*
- hh is the hour of the day (00 through
* 23), as two decimal digits.
*
- mm is the minute within the hour (00 through
* 59), as two decimal digits.
*
- ss is the second within the minute (00 through
* 61, as two decimal digits.
*
- zzz is the time zone (and may reflect daylight saving
* time). Standard time zone abbreviations include those
* recognized by the method parse. If time zone
* information is not available, then zzz is empty -
* that is, it consists of no characters at all.
*
- yyyy is the year, as four decimal digits.
*
*
* @return a string representation of this date.
*/
public String toString() {
return null;
}
/**
* Reconstitute this object from a stream (i.e., deserialize it).
*/
private void readObject(ObjectInputStream s)
throws IOException, ClassNotFoundException
{ }
/**
* Save the state of this object to a stream (i.e., serialize it).
*
* @serialData The value returned by getTime()
* is emitted (long). This represents the offset from
* January 1, 1970, 00:00:00 GMT in milliseconds.
*/
private void writeObject(ObjectOutputStream s) throws IOException { }
}