comefrom: <awangdev>[lint]. Unique Characters_2.java
code: public boolean isUnique(String str) {
      	if (str == null || str.length() == 0) {
      		return true;
      	}
      	HashSet<Character> set = new HashSet<Character>();
      	for (int i = 0; i < str.length(); i++) {
      		if (!set.contains(str.charAt(i))) {
      			set.add(str.charAt(i));
      		} else {
      			return false;
      		}
      	}
  
      	return true;
      }
masked: public boolean var_0 ( String var_1 ) {
    if ( var_1 == null || var_1 . length ( ) == 0 ) {
      return true ;
    }
    HashSet < Character > var_2 = new HashSet < Character > ( ) ;
    for ( int var_3 = 0 ;
    var_3 < var_1 . length ( ) ;
    var_3 ++ ) {
      if ( ! var_2 . contains ( var_1 . charAt ( var_3 ) ) ) {
        var_2 . add ( var_1 . charAt ( var_3 ) ) ;
      }
      else {
        return false ;
      }
    }
    return true ;
  }
  