SimpleTimeZone setStartRule(int, int, int) method in Java with Examples

The setStartRule(int startofMonth, int startofDay, int startofTime) method of SimpleTimeZone class in Java is used to set a particular start rule of the day-light saving time to a fixed date within a given month.

Syntax:

public void setStartRule(int startofMonth, 
                              int startofDay, 
                              int startofTime)

Parameters: The method takes three parameters:

• startofMonth: This is of Integer type and refers to the Starting month of the daylight saving time.
• startofDay: This is of Integer type and refers to the Starting day of the daylight saving time.
• startofTime: This is of Integer type and refers to the Starting time of the daylight saving time.

Return Value: The method does not return any value.

Below programs illustrate the use of setStartRule() Method in Java:
Example 1:

// Java code to demonstrate
// setStartRule() method

import java.util.*;

public class SimpleTimeZone_Demo {
    public static void main(String[] args)
    {

        // Creating SimpleTimeZone object
        SimpleTimeZone simtimeobj
            = new SimpleTimeZone(100, "GMT");

        // Displaying the Initial value
        System.out.println(
            "Initial value: " + simtimeobj);

        // Setting an StartRule
        simtimeobj.setStartRule(Calendar.APRIL,
                                28, 3600000);

        // Displaying the New value
        System.out.println(
            "New value: " + simtimeobj);
    }
}

Output:

Initial value: java.util.SimpleTimeZone[id=GMT, offset=100, dstSavings=3600000,
useDaylight=false, startYear=0, startMode=0, startMonth=0, startDay=0, startDayOfWeek=0,
startTime=0, startTimeMode=0, endMode=0, endMonth=0, endDay=0, endDayOfWeek=0, endTime=0,
endTimeMode=0]

New value: java.util.SimpleTimeZone[id=GMT, offset=100, dstSavings=3600000,
useDaylight=false, startYear=0, startMode=1, startMonth=3, startDay=28, startDayOfWeek=0,
startTime=3600000, startTimeMode=0, endMode=0, endMonth=0, endDay=0, endDayOfWeek=0,
endTime=0, endTimeMode=0]

Example 2:

// Java code to demonstrate
// setStartRule() method

import java.util.*;

public class SimpleTimeZone_Demo {
    public static void main(String[] args)
    {

        // Creating SimpleTimeZone object
        SimpleTimeZone simtimeobj
            = new SimpleTimeZone(120, "GMT");

        // Displaying the Initial value
        System.out.println(
            "Initial value: " + simtimeobj);

        // Setting an StartRule
        simtimeobj.setStartRule(Calendar.JANUARY,
                                15, 3600000);

        // Displaying the New value
        System.out.println(
            "New value: " + simtimeobj);
    }
}

Output:

Initial value: java.util.SimpleTimeZone[id=GMT, offset=120, dstSavings=3600000,
useDaylight=false, startYear=0, startMode=0, startMonth=0, startDay=0, startDayOfWeek=0,
startTime=0, startTimeMode=0, endMode=0, endMonth=0, endDay=0, endDayOfWeek=0, endTime=0,
endTimeMode=0]

New value: java.util.SimpleTimeZone[id=GMT, offset=120, dstSavings=3600000,
useDaylight=false, startYear=0, startMode=1, startMonth=0, startDay=15, startDayOfWeek=0,
startTime=3600000, startTimeMode=0, endMode=0, endMonth=0, endDay=0, endDayOfWeek=0,
endTime=0, endTimeMode=0]

Reference: https://docs.oracle.com/javase/10/docs/api/java/util/SimpleTimeZone.html#setStartRule(int,int,int)