Here is the Java code:

public class DayType{
        final static int SUN = 0;
        final static int MON = 1;
        final static int TUE = 2;
        final static int WED = 3;
        final static int THU = 4;
        final static int FRI= 5;
        final static int SAT = 6;

        private int day;

        public DayType(int day) {
                this.day = day;
        }

        public void setDay(int day){
                this.day = day;
        }

        public int getDay() {
                return day;
        }

        public void print() {
                System.out.println(this.toString());
        }
        public int nextDay(){
                int next;
                next = day + 1;
                return next;
        }
        public int previousDay(){
                int prevDay;
                prevDay = day - 1;
                return prevDay;
        }
        public int addDays(int days) {
                return (day + days) % 7;
        }
                public String toString() {
                switch (this.day) {
                case SUN:
                        return "Sunday";
                case MON:
                        return "Monday";
                case TUE:
                        return "Tuesday";
                case WED:
                        return "Wednesday";
                case THU:
                        return "Thursday";
                case FRI:
                        return "Friday";
                case SAT:
                        return "Saturday";
                }
                return "";
        }       
        public static void main(String[] args) {
                System.out.println("******Test Day******");
                System.out.println();
                System.out.print("Set day: ");
                DayType d = new DayType(SUN);
                d.print();
                System.out.print("Next day: ");
                d.setDay(d.nextDay());
                d.print();
                System.out.print("Previous day: ");
                d.setDay(d.previousDay());
                d.print();
                System.out.print("After 5 days: ");
                d.setDay(d.addDays(5));
                d.print();
        }       
}