 package unit7problemset;
 import java.util.*;
 public class Main
 {
//     String menu = Constants.menu;
     public void menu()
     {
         System.out.println(Constants.menu);
     }
     public static void main(String[] args)
     {
         Main main = new Main();
         main.menu();
     }
 }
 package pack;
 import java.util.*;
 public class Main
 {
//     String menu = Constants.menu;
     public void menu()
     {
         System.out.println(Constants.menu);
     }
     public static void main(String[] args)
     {
         Main main = new Main();
         main.menu();
     }
 }

Update Main.java