Java repeated letter check in string

Question

I\'m having problem figuring out how to check from users input letters that were repeated. Program needs to output repeated letter as true and if there isn\'t any then as false.

Answer 1

private static boolean check(String input) {
    Set tmp = new HashSet();
    for(char ch : input.toCharArray()) {
        if (Character.isLetter(ch) && !tmp.add(ch)) {
            return true;
        }
    }
    return false;
}