Find Duplicate Characters
1234567891011121314151617181920
import java.util.Set;
import java.util.HashSet;
class Main {
public static void main(String[] args) {
System.out.println(findDuplicateCharater("papper"));
}
public static String findDuplicateCharater(String s){
Set<Character> charSet = new HashSet<>();
Set<Character> res = new HashSet<>();
for(char a : s.toCharArray()){
if(charSet.contains(a)){
res.add(a);
}
else{
charSet.add(a);
}
}
return res.toString();
}
}
Java
INFO