Check the String whether it has the same character.

UniqunessCheck2

public boolean isUnique(String str) {
	boolean isUnique = true;
	HashSet<Character> hs = new HashSet<>();
	for(char c: str.toCharArray()){
		if(!hs.contains(c)){
			hs.add(c);
		}else{
			isUnique = false;
			break;
		}
	}	
	return isUnique;
}