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Chapter 17 The java.util Package |
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Chapter 17 The java.util Package |
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java.util.Date
java.lang.Object
None
java.lang.Cloneable, java.io.Serializable
JDK 1.0 or later
The Date class encapsulates a point in time with millisecond precision. The value of a Date is represented internally by a long value that contains the number of milliseconds since midnight, January 1, 1970 GMT.
Prior to JDK 1.1, the Date class was used for two purposes that are now encapsulated by other classes. First, the Date class included methods for calculating calendar values, like months and days of the week. This functionality is now embedded in the Calendar class. Second, the Date class included methods for generating and parsing a string representation of a date. This functionality is now provided by java.text.DateFormat. Thus, as of JDK 1.1, most of the methods of Date are deprecated; the class is used only to represent a point in time.
The accurate measurement of time is a subject of considerable complexity and multifarious acronyms. There are two main methods of measuring time, atomic and astronomical. The U.S. Naval Observatory (http://tycho.usno.navy.mil) maintains a set of atomic clocks that provide the basis for Coordinated Universal Time (UTC). These clocks adhere to precise definitions of the second based on atomic decay.
Outside of the U.S. Navy, people tend to measure time in terms of Greenwich Mean Time (GMT). In the scientific community, GMT is called UT, which is a system of time predicated on the assumption that each rotation of the earth is exactly 24 * 60 * 60 seconds long. Because the earth's rotation is gradually slowing down, the seconds in UT are a little bit longer than the seconds in UTC. Now and then a "leap second" is added in UTC to keep it close to UT. Because the Date class simply measures milliseconds since a point in time, without regard for leap seconds, it is a good representation of UT or GMT.
public class java.util.Date extends java.lang.Object
implements java.lang.Cloneable, java.io.Serializable {
// Constructors
public Date();
public Date(long date);
public Date(int year, int month, int date); // Deprecated in 1.1
public Date(int year, int month, int date,
int hrs, int min); // Deprecated in 1.1
public Date(int year, int month, int date,
int hrs, int min, int sec); // Deprecated in 1.1
public Date(String s); // Deprecated in 1.1
// Class Methods
public static long parse(String s); // Deprecated in 1.1
public static long UTC(int year, int month,
int date, int hrs,
int min, int sec); // Deprecated in 1.1
// Instance Methods
public boolean after(Date when);
public boolean before(Date when);
public boolean equals(Object obj);
public int getDate(); // Deprecated in 1.1
public int getDay(); // Deprecated in 1.1
public int getHours(); // Deprecated in 1.1
public int getMinutes(); // Deprecated in 1.1
public int getMonth(); // Deprecated in 1.1
public int getSeconds(); // Deprecated in 1.1
public long getTime();
public int getTimezoneOffset(); // Deprecated in 1.1
public int getYear(); // Deprecated in 1.1
public int hashCode();
public void setDate(int date); // Deprecated in 1.1
public void setHours(int hours); // Deprecated in 1.1
public void setMinutes(int minutes); // Deprecated in 1.1
public void setMonth(int month); // Deprecated in 1.1
public void setSeconds(int seconds); // Deprecated in 1.1
public void setTime(long time);
public void setYear(int year); // Deprecated in 1.1
public String toGMTString(); // Deprecated in 1.1
public String toLocaleString(); // Deprecated in 1.1
public String toString();
}
This constructor creates a Date object that is initialized to the current time.
A time value, measured as the number of milliseconds since midnight, January 1, 1970 GMT.
This constructor creates a Date object that represents the given time.
Deprecated as of JDK 1.1
The year specified as a value that is added to 1900 to get the actual year.
The month specified in the range 0 to 11.
The day of the month specified in the range 1 to 31.
This constructor creates a Date that represents midnight local time on the specified date.
Deprecated as of JDK 1.1
The year specified as a value that is added to 1900 to get the actual year.
The month specified in the range 0 to 11.
The day of the month specified in the range 1 to 31.
The hours specified in the range 0 to 23.
The minutes specified in the range 0 to 59.
This constructor creates a Date that represents the given date and time.
public Date(int year, int month, int day, int hrs, int min, int sec)
Deprecated as of JDK 1.1
The year specified as a value that is added to 1900 to get the actual year.
The month specified in the range 0 to 11.
The day of the month specified in the range 1 to 31.
The hours specified in the range 0 to 23.
The minutes specified in the range 0 to 59.
The seconds specified in the range 0 to 59.
This constructor creates a Date that represents the given date and time.
Deprecated as of JDK 1.1
The string to parse.
This constructor creates a Date that represents the date and time specified by the given string. The syntax of the date in the string must satisfy the requirements of the parse() method. The following is an example of a string that this constructor can understand:
Sat, 8 Feb 1997 13:30:00 GMT
Deprecated as of JDK 1.1
The string to parse.
A time value represented as the number of milliseconds since midnight, January 1, 1970 GMT.
If the string cannot be parsed.
This method returns the raw time value specified by the given string. This method understands a number of different formats. The following are examples of strings that this method can understand:
Sat, 8 Feb 1997 13:30:00 GMT 4/6/97 4/6/1997 January 5, 1997 2/4/97 11:03 AM 2/4/97 10:25 PM 2/4/97 17:03 GMT-6 2/4/97 17:03:24 March 16, 97 17:03 EST March (comment)16, 97 (comment) 17:03 EST 16 march 1996 17:03 pdt Sat 16 march 97 17:03 cst
The JDK 1.0.2 implementation of parse() has a serious bug. It incorrectly interprets date formats that specify the month as a number by making the month one greater than it should be. So 2/4/97 is incorrectly interpreted as March 4, 1997.
For the purposes of this method, UTC and GMT are considered equivalent.
public static long UTC(int year, int month, int date, int hrs, int min, int sec)
Deprecated as of JDK 1.1
The year specified as a value that is added to 1900 to get the actual year.
The month specified in the range 0 to 11.
The day of the month specified in the range 1 to 31.
The hours specified in the range 0 to 23.
The minutes specified in the range 0 to 59.
The seconds specified in the range 0 to 59.
A time value represented as the number of milliseconds since midnight, January 1, 1970 GMT.
This method returns a raw time value that corresponds to the given parameters. Computations are based on GMT, not the local time zone.
The object to compare to this Date.
true if this object is after when; false otherwise.
This method returns true if the value of when falls before the value of this Date.
The object to compare to this Date.
true if this object is before when; false otherwise.
This method returns true if the value of when falls after the value of this Date.
The object to be compared with this object.
true if the objects are equal; false if they are not.
Object.equals()
This method returns true if when is an instance of Date and it contains the same value as the object this method is associated with. In other words, the two Date objects are equal only if they both represent the same point in time, to the millisecond.
Deprecated as of JDK 1.1
The day of the month of this Date.
This method returns the day of the month represented by this Date object. The value is in the range 1 to 31.
Deprecated as of JDK 1.1
The day of the week of this Date.
This method returns the day of the week represented by this Date object. The value is in the range 0 to 6, where 0 means Sunday.
Deprecated as of JDK 1.1
The hour value of this Date.
This method returns the hour represented by this Date object. The value is in the range 0 to 23, where 0 means midnight.
Deprecated as of JDK 1.1
The minute value of this Date.
This method returns the number of minutes after the hour represented by this Date object. The value is in the range 0 to 59.
Deprecated as of JDK 1.1
The month of this Date.
This method returns the month represented by this Date object. The value is in the range 0 to 11, where 0 means January.
Deprecated as of JDK 1.1
The second value of this Date.
This method returns the number of seconds after the minute represented by this Date object. The value is in the range 0 to 59.
The raw time value of this Date.
This method returns the date and time of this Date as the number of milliseconds since midnight, January 1, 1970 GMT.
Deprecated as of JDK 1.1
The time zone offset for this Date.
This method returns the number of minutes between the local time zone and GMT for this Date object.
Deprecated as of JDK 1.1
The year of this Date.
This method returns the year represented by this Date object. The value is the number of years since 1990.
The hashcode for this Date.
Object.hashCode()
This method returns a hashcode for this object.
Deprecated as of JDK 1.1
The day of the month specified in the range 1 to 31.
This method sets the day of the month of this Date object.
Deprecated as of JDK 1.1
The hours specified in the range 0 to 23.
This method sets the hour of this Date object.
Deprecated as of JDK 1.1
The minutes specified in the range 0 to 59.
This method sets the minute value of this Date object.
Deprecated as of JDK 1.1
The month specified in the range 0 to 11.
This method sets the month of this Date object
Deprecated as of JDK 1.1
The seconds specified in the range 0 to 59.
This method sets the second value of this Date object.
A time value specified as the number of milliseconds since midnight, January 1, 1970 GMT.
This method sets the date and time represented by this Date to the given raw time value.
Deprecated as of JDK 1.1
The year specified as a value that is added to 1900 to get the actual year.
This method sets the year of this Date object.
Deprecated as of JDK 1.1
A string that represents this Date.
The method returns a string representation of this Date object based on Internet GMT conventions. The string is of the form:
Sat, 8 Feb 1997 13:30:00 GMT
The date is the string is either one or two digits; the rest of the fields always have the width shown. The time zone is always GMT.
Deprecated as of JDK 1.1
A string that represents this Date.
The method returns a string representation of this Date based on the conventions of the current locale.
A string that represents this Date.
Object.toString()
This method returns a string representation of this Date. The string is of the form:
Sat Feb 8 2:30:00 MST 1997
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Method |
Inherited From |
Method |
Inherited From |
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clone() |
Object |
finalize() |
Object |
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getClass() |
Object |
notify() |
Object |
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notifyAll() |
Object |
wait() |
Object |
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wait(long) |
Object |
wait(long, int) |
Object |
Calendar, Cloneable, DateFormat, GregorianCalendar, IllegalArgumentException, Serializable, TimeZone
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| Calendar |  |
Dictionary |
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