togglecase

import java.util.*;

public class Main {
    public static void main(String[] args)
    {
        Scanner sc = new Scanner(System.in);
        String str = "Hello WorlD";
        int choice = 1;
        char[] arr= str.toCharArray();

        while (choice != 4) {
            System.out.println("1. Uppercase");
            System.out.println("2. Lowercase");
            System.out.println("3. ToggleCase");
            System.out.println("4. Exit");

            System.out.print("\nEnter your choice : ");
            choice = sc.nextInt();

            if (choice == 1) {
                System.out.println("Upper : " + str.toUpperCase());
            }
            else if (choice == 2) {
                System.out.println("Lower : " + str.toLowerCase());
            }
            else if (choice == 3) {
                System.out.print("Toggle : ");
                for (char ch : arr) {
                    if(Character.isUpperCase(ch)){
                        ch= Character.toLowerCase(ch);
                    }
                    else if(Character.isLowerCase(ch)){
                        ch= Character.toUpperCase(ch);
                    }
                    System.out.print(ch);
                }
            }
            else if (choice == 4) {
                System.out.println("Program Terminated");
            }
            System.out.println();
        }
    }
}