util.date class methods in Java with Examples

Following are some important date class methods :

1. .toString() : java.util.Date.tostring() method is a java.util.Date class method.It displays the Current date and time.
   Here Date object is converted to a string and represented as:

    day mon dd hh:mm:ss zz yyyy 

   day : day of the week
   mon : month
   dd : day of the month
   hh : hour
   mm : minute
   ss : second
   zz : time zone
   yyyy : year upto 4 decimal places

   Syntax:
   public String toString()
   Return:
   a string representation of the given date.
   

2. .setTime() : java.util.Date.setTime() method is a java.util.Date class method. Sets this Date object to represent a point in time that is time milliseconds after January 1, 1970 00:00:00 GMT.

   Syntax:
   public void setTime(long time)
   Parameters:
   time : the number of milliseconds.
   

3. .hashCode() : java.util.Date.hashCode() method is a java.util.Date class method. Returns a hash code value for the Date object. The result is exclusive OR of the two halves of the primitive long value returned by the getTime() method.

   Syntax:
   public int hashCode()
   Return:
   a hash code value for the Date object.
   

   Java Code to illustrate the use of .toString(), setTime(), hashCode() methods.

   
   

   
   
   

   // Java Program explaining util.date class methods// // use of .toString(), setTime(), hashCode() methods import java.util.*;  // class having access to Date class methods    public class NewClass {     public static void main(String[] args)     {         Date mydate = new Date();            // Displaying the current date and time         System.out.println("System date : "+ mydate.toString() );            // Is used to set time by milliseconds. Adds 15680          // milliseconds to January 1, 1970 to get new time.         mydate.setTime(15680);            System.out.println("Time after setting:  " + mydate.toString());            int d = mydate.hashCode();         System.out.println("Amount (in ms) by which time" +                             " is shifted :  " + d);     } }

   Output of Java code:

   System date : Tue Nov 01 02:37:18 IST 2016
   Time after setting:  Thu Jan 01 05:30:15 IST 1970
   Amount (in milliseconds)  by which time is shifted :  15680
   

4. .after() : java.util.Date.after() method tests if current date is after the given date.

   Syntax:
   public boolean after(Date d)
   Parameters:
   d : date
   Return:
   true if and only if the instant represented by this Date object is strictly later
   than the instant represented by 'when'; else false
   Exception:
   NullPointerException - if Date object is null.
   

5. .clone() : java.util.Date.clone() method returns the duplicate of passed Date object.

   Syntax:
   public Object clone()
   Return:
   a clone of this instance.
   

6. .before() : java.util.Date.after() method tests if current date is before the given date.

   Syntax:
   public boolean before(Date d)
   Parameters:
   d : date
   Return:
   true if and only if the instant represented by this Date object is strictly earlier
   than the instant represented by 'when'; else false
   Exception:
   NullPointerException - if when is null.
   

Java Code to illustrate the use of after(), clone(), before() methods.








// JAVA program explaining Date class methods // after(), clone(), before() import java.util.Date; public class NewClass {     public static void main(String[] args)     {         // create 2 dates         Date date1 = new Date(2016, 11, 18);         Date date2 = new Date(1997, 10, 27);            // Use of after() to check date2 is after date1         boolean a = date2.after(date1);         System.out.println("Is date2 is after date1 : " + a);            // Use of after() to check date2 is after date1         a = date1.after(date2);         System.out.println("Is date1 is after date2 : " + a);         System.out.println("");            // Use of clone() method         Object date3 = date1.clone();         System.out.println("Cloned date3 :" + date3.toString());         System.out.println("");            // Use of before() to check date2 is after date1         boolean b = date2.before(date1);         System.out.println("Is date2 is before date1 : " + a);     } }

Output :

Is date2 is after date1 : false
Is date1 is after date2 : true

Cloned date3 :Mon Dec 18 00:00:00 IST 3916

Is date2 is before date1 : true

7. .compareTo() : java.util.Date.compareTo() method compares two dates and results in -1, 0 or 1 based on the comparison.

   Syntax:
   public int compareTo(Date argDate)
   Parameters:
   argDate : another date to compare with
   Result:
   0  : if the argumented date = given date.
   -1 : if the argumented date > given date.
   1  : if the argumented date < given date.
   

8. .equals() : java.util.Date.equals() method checks whether two dates are equal or not based on their millisecond difference.

   Syntax:
   public boolean equals(Object argDate)
   Parameters:
   argDate : another date to compare with
   Result:
   true if both the date are equal; else false.
   

9. .getTime() : java.util.Date.getTime() method results in count of milliseconds of the argumented date, referencing January 1, 1970, 00:00:00 GMT.

   Syntax:
   public long getTime()
   Result:
   milliseconds of the argumented date, referencing January 1, 1970, 00:00:00 GMT.
   

Java Code to illustrate the use of compareTo(), getTime(), equals() methods.








// Java program explaining Date class methods // compareTo(), getTime(), equals() import java.util.*; public class NewClass {     public static void main(String[] args)     {         Date d1 = new Date(97, 10, 27);         Date d2 = new Date(97, 6, 12);            // Use of compareto() method         int comparison = d1.compareTo(d2);    // d1 > d2         int comparison2 = d2.compareTo(d1);   // d2 > d1         int comparison3 = d1.compareTo(d1);   // d1 = d1            System.out.println("d1 > d2 : " + comparison);         System.out.println("d1 < d2 : " + comparison2);         System.out.println("d1 = d1 : " + comparison3);         System.out.println("");            // Use of equal() method         boolean r1 = d1.equals(d2);         System.out.println("Result of equal() r1 : " + r1);            boolean r2 = d1.equals(d1);         System.out.println("Result of equal() r2 : " + r2);         System.out.println("");               // Use of getTime() method         long count1 = d1.getTime();         long count2 = d1.getTime();         System.out.println("Milliseconds of d1 : " + count1);         System.out.println("Milliseconds of d2 : " + count2);     } }

Output :

d1 > d2 : 1
d1 < d2 : -1
d1 = d1 : 0

Result of equal() r1 : false
Result of equal() r2 : true

Milliseconds of d1 : 880569000000
Milliseconds of d2 : 880569000000

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