How can I invert the case of a String in Java?

Question

I want to change a String so that all the uppercase characters become lowercase, and all the lower case characters become uppercase. Number characters are just ignored.

Answer 1

public class ReverseCase {
    public  static void main(String[] args){ 
        char[] char_arr = args[0].toCharArray();
        for (int i = 0; i < char_arr.length; i++) {
            if (Character.isLowerCase(char_arr[i])) {
                char_arr[i] = Character.toUpperCase(char_arr[i]);
            }else {
                char_arr[i] = Character.toLowerCase(char_arr[i]);
            }
        }
        String reversed = new String(char_arr);
        System.out.println(reversed);
    }
}