public void CreateMultipleUniqueAddressBook() { while (true) { Console.WriteLine("Please enter your Choice......."); Console.WriteLine("1.Add Address Book"); Console.WriteLine("2.Use Existing Address Book"); Console.WriteLine("3.Exit"); String choice = Console.ReadLine(); int choice1 = Convert.ToInt32(choice); switch (choice1) { case 1: Console.WriteLine("Please Enter The Name Of Your Address Book : "); string name = Console.ReadLine(); if (dictionary.ContainsKey(name)) { Console.WriteLine("Address Book Already exists!!!"); } else { AddPersonDetails addressBook = new AddPersonDetails(); dictionary.Add(name, addressBook); Console.WriteLine("Your Address Book is Created."); addressBook.Menu(); } break; case 2: Console.WriteLine("Please enter Address book name : "); string addressBookName = Console.ReadLine(); if (dictionary.ContainsKey(addressBookName)) { dictionary[addressBookName].Menu(); } else { Console.WriteLine("Address book does not exists!!!"); } break; case 3: return; } } }