mstoic/reverse_a_string_using_string_builder

## reverse_a_string_using_string_builder
StringBuilder str = new StringBuilder("Hey");
int len = str.length();
for (int i = 0; i < len; i++) {
    str.append(str.substring(len - 1 - i, len - i));
}
str.delete(0, len);
System.out.println("string: " + str);
	StringBuilder str = new StringBuilder("Hey");
	int len = str.length();
	for (int i = 0; i < len; i++) {
	str.append(str.substring(len - 1 - i, len - i));
	}
	str.delete(0, len);
	System.out.println("string: " + str);