public class ReverseString {
public static void main(String[] args) {
String str = "789";
System.out.println(reverseString(str));
}
public static String reverseString(String in) {
if (in == null)
throw new IllegalArgumentException("input null");
StringBuilder out = new StringBuilder();
char[] chars = in.toCharArray();
for (int i = chars.length - 1; i >= 0; i--)
out.append(chars[i]);
return out.toString();
}
}