public void set(int day_val)

// Java code to illustrate
// setFirstDayOfWeek() method
  
import java.util.*;
  
public class Calendar_Demo {
    public static void main(String args[])
    {
  
        // Creating calendar object
        Calendar calndr = Calendar.getInstance();
  
        // Displaying first day of the week
        int first_day = calndr.getFirstDayOfWeek();
        System.out.println("The Current"
                           + " First day of the week: "
                           + first_day);
  
        // Changing the first day of week
        calndr.setFirstDayOfWeek(Calendar.THURSDAY);
  
        // Displaying the alternate day
        first_day = calndr.getFirstDayOfWeek();
        System.out.println("The new first"
                           + " day of the week: "
                           + first_day);
    }
}

The Current First day of the week: 1
The new first day of the week: 5

// Java code to illustrate
// setFirstDayOfWeek() method
  
import java.util.*;
public class Calendar_Demo {
    public static void main(String args[])
    {
  
        // Creating calendar object
        Calendar calndr
            = new GregorianCalendar(2018, 6, 10);
  
        // Displaying first day of the week
        int first_day = calndr.getFirstDayOfWeek();
        System.out.println("The"
                           + " First day of the week: "
                           + first_day);
  
        // Changing the first day of week
        calndr.setFirstDayOfWeek(Calendar.MONDAY);
  
        // Displaying the alternate day
        first_day = calndr.getFirstDayOfWeek();
        System.out.println("The new first"
                           + " day of the week: "
                           + first_day);
    }
}

The First day of the week: 1
The new first day of the week: 2