String string = "hello_World_Hi";
        String s = "_";
        int length = string.length();
        char c = ' ';

        if (string.contains(s))
        {
            for (int i = 0; i < length; i++)
            {
                if (string.charAt(i) == '_')
                {
                    if (true)
                    {
                        c = string.charAt(i+1);
                    }
                }
            }
        }

        if (Character.isUpperCase(c))
        {
            c = Character.toLowerCase(c);
        }
        System.out.println(c);