Implementation of DayType class

import java.util.*;
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 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){
            DayType d = new DayType();
            Scanner input=new Scanner(System.in);
            boolean check=false;
            do{
            System.out.println("******Test Day******");
            System.out.println("1 Set day");
            System.out.println("2 Print day");
            System.out.println("3 Return day");
            System.out.println("4 Return Previous day");
            System.out.println("5 Return Next day");
            System.out.println("6 Exit");
            System.out.println();

            System.out.print("Enter your choice: ");
            int num=input.nextInt();
            switch(num){
            case 1:
            System.out.print("Set day(0-6): ");
            int day=input.nextInt();
            d.setDay(day);
            break;
            case 2:
            d.print();
            break;
            case 3:
            System.out.print("Next day: ");
            d.setDay(d.nextDay());
            d.print();
            break;
            case 4:
            System.out.print("Previous day: ");
            d.setDay(d.previousDay());
            d.print();
            case 5:
            System.out.print("Add no of days: ");
            int no=input.nextInt();
            d.setDay(d.addDays(no));
            d.print();
            break;
            case 6:
            check=true;
            break;
            }
            }
            while(!check);
    }
}

thank you very much friend...