Need some tips as to what a part of code does

Question

I have an assignment to do, and my teacher provided me with a part of code which could help doin said assignment. But I am unsure of one part of it;

String utenRepetisjon(String tekst){

    String resultat = ""; 
    for (int i = 0; i < tekst.length(); i++){
        if (!tekst.charAt(i), resultat){ //Here I need help, if someone could be an angel and explain to me what this line does: !tekst.charAt(i), resultat). I know that it it something like: if the char at spot i in the string is not present, then something, but what's up with the comma?
            resultat += tekst.charAt(i); 
        }
    }
    return resultat; 

}

To add to the fact that it doesn't compile it also uses string concatenation in a loop. A good teacher you have there... — Boris the Spider, Oct 16 '13 at 19:47
@BoristheSpider the compiler will turn that into a `StringBuilder`..not a huge deal but yeah, you're right. — yamafontes, Oct 16 '13 at 19:47
This may help you. http://www.cplusplus.com/forum/general/22745/ — , Oct 16 '13 at 19:48
what's wrong with string concat in a loop? Are you referring to using a stringbuilder as a better option? — Millie Smith, Oct 16 '13 at 19:48
@KepaniHaole that's not guaranteed by the JLS and it almost certainly won't in a loop. — Boris the Spider, Oct 16 '13 at 19:48
@KepaniHaole really? I didn’t know that. A pointer to some documentation stating it? — Étienne Miret, Oct 16 '13 at 19:48
@EtienneMiret http://docs.oracle.com/javase/specs/jls/se5.0/html/expressions.html#15.18.1.2 — yamafontes, Oct 16 '13 at 19:49
that's too advanced for cs1 (stringbuilder). That gets into memory management. Let them scrape the surface — Millie Smith, Oct 16 '13 at 19:49
@KepaniHaole [Not a big deal](http://kaioa.com/node/59)? You have must have a strange definition of a big deal. — Boris the Spider, Oct 16 '13 at 19:50
@KepaniHaole My research shows that the compiler won’t optimize to a string builder in a loop. See http://stackoverflow.com/questions/4645020/when-to-use-stringbuilder-in-java for example. — Étienne Miret, Oct 16 '13 at 20:03
Very well. So this is a different language altogether then. Well, does anyone have a suggestion on what to replace it with so that: the if-loop check whether the charAt(i) is currently represented in the resultat-variable. — Makri, Oct 16 '13 at 20:26
Nevermind, I replaced the if-loop with: !resultat.contains(Character.toString(charAt(i)))) and it worked. The result looked f-ed up, but it was supposed to only let one occurrence of every letter in the string so it was intended :P — Makri, Oct 16 '13 at 20:29

Henry Keiter · Answer 1 · 2013-10-16T19:55:37.063

0

You're right to be confused. It looks like someone forgot what language they were using and tried to insert some C++ syntax. This will not compile in Java.

Probably what was intended was to compare tekst.charAt(i) to something, and proceed if that comparison returned false. However, that comma and floating identifier are just bad syntax, and simple do not compile.

edited Oct 16 '13 at 19:55

answered Oct 16 '13 at 19:50

Henry Keiter

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Need some tips as to what a part of code does

1 Answers1