Java - printing random word

Question

I'm having problems with an exercise. I need to print five random words, between min and max letters.

This is what I've done:

package Vjezba;
import acm.program.*;
import acm.util.RandomGenerator;
import java.util.*;
public class String2 extends ConsoleProgram {
public void run () {
 for (int i = 0; i<5; i++){
 String a = randomWord();
 println(a);
 }
}
private String randomWord() {
 int a = rgen.nextInt(MIN_LETTER, MAX_LETTER);
 for (int x=0; x<a; x++){
 String niz = "";
 char c = randomChar();
 niz += 'c';
 }
 return niz;
}
private char randomChar(){
 return (char) rgen.nextInt('a', 'z');
}
private static RandomGenerator rgen = new RandomGenerator();
private static int MIN_LETTER = 3;
private static int MAX_LETTER = 10;
 }

I have problems with returning String. Dunno how to do it.

• Anthony Grist: What do you mean when you say you "have problems"? Are you getting an exception? Is nothing being returned?
• amit: +1 for asking help after you are stuck, and not asking us to do your homework for you.

Answer 1

You're declaring your String inside your for loop; every time it loops you get a new (empty) String. You're also adding the character 'c', not the contents of your char c

String niz = "";
for (int x=0; x<a; x++){
 //String niz = "";
 char c = randomChar();
 niz += c; // c not 'c'
}

And while in this trivial case it doesn't really matter, a String in java is immutable - it can't be changed. Every time you do niz += c it creates a new string. Any time you're building a string you want to use a StringBuilder:

StringBuilder niz = new StringBuilder();
for (int x=0; x<a; x++){
 char c = randomChar();
 niz.append(c);
}
return niz.toString();

Answer 2

Ignore my comment, I hadn't woken up yet. Your randomWord() has a scope issue; you're declaring your String variable inside of your for loop and then trying to return it after the loop ends - I imagine you're getting a compile error. Modify it so that the empty String declaration is before the for loop.

Answer 3

niz += 'c'; should be niz = niz + c; or niz += c; [personally I prefer the first, since it is more clear that the object is not modified but the reference is changed].

also, niz should be declared out of the loop's scope [before the for line].

String niz = "";
for (int x=0; x<a; x++){
 char c = randomChar();
 niz = niz + c;
}
return niz;

you might want to use StringBuilder if performance is an issue, but I don't think it is the case in here.

• Brian Roach: += works just fine (though, not really as it creates a new String every time the same as niz = niz + c;)
• amit: @Brian Roach: Read my answer, I said I prefer it for clarity, not that it doesn't work, the "doesn't work" part refers to 'adding' 'c' instead of c.
• Brian Roach: Yes, now that you've edited it it does say that. And it notes the problem with the String being declared in the loop and the StringBuilder from my answer ...
• amit: @Brian Roach: my answer was editted 8 mins ago, yours 2 mins ago. your comment is 6 mins ago, stop trolling.
• Brian Roach: Care to look at the edit and see the only thing I added was // c not 'c' or do you want to keep playing this game?