Return as String Value from For Loop Java

Question

I'm trying to create a loop of 50 characters and then return the whole 50 characters as a String, but unfortunately the String is only returning the last letter, and not all 50 characters. getRandomUpperChar() is just a method I created to get a random Uppercase char value from 'A' to 'Z'.

public static String initializeKey(int num , int minNum, int maxNum) {
    String random = "";
    for(int j = 0; j <num; j++) {
        getRandomUpperChar();
        char Xp = getRandomUpperChar(minNum, maxNum);

        random = "" +  Xp;
        System.out.print(random);
    }
    return random;
}

Out of curiosity, what is the method call to getRandomUpperChar() with no args doing on line 4? Is your method overloaded? If so, what does the no-arg method do? — James Dunn
– James Dunn, Commented Nov 14, 2014 at 23:32

Sybren · Accepted Answer · 2014-11-14 23:39:24Z

2

You are missing something very basic

random+= "" +Xp

edited Nov 14, 2014 at 23:39

Sybren

1,0793 gold badges18 silver badges53 bronze badges

answered Nov 14, 2014 at 23:17

Vatsal

2,1384 gold badges23 silver badges28 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

kris Over a year ago

Oh my goodness, I can't believe I didn't see that. Thank you so much kind sir.

Tom Over a year ago

You can also write random += Xp;. Looks much cleaner and it works, due to the correct random variable.

GreyBeardedGeek · Accepted Answer · 2014-11-14 23:26:48Z

2

Well, replacing

random = "" +  Xp;

with

random = random +  Xp;

would make it work, but a better solution would be:

public static String initializeKey(int num, int minNum, int maxNum) {
  StringBuilder random = new StringBuilder();

  for(int j = 0; j < num; j++){
     char xp = getRandomUpperChar(minNum, maxNum);
     random.append(xp);
  }

  return random.toString(); 
}

edited Nov 14, 2014 at 23:26

answered Nov 14, 2014 at 23:21

GreyBeardedGeek

30.3k2 gold badges51 silver badges71 bronze badges

1 Comment

GreyBeardedGeek Over a year ago

string concatenation (random = random + xp) allocates at least 2 new Strings each time you do it, which tends to thrash the garbage collector. The method shown above allocates one StringBuilder and one String, and is much preferred.

mattias · Accepted Answer · 2014-11-14 23:19:43Z

1

Just replace your

random = "" +  Xp;

with

random +="" + Xp;

and you would be fine.

answered Nov 14, 2014 at 23:19

mattias

2,0983 gold badges20 silver badges27 bronze badges

2 Comments

kris Over a year ago

Thank you as well mattias! I knew it must be something simple, but I couldn't of the life of me figure it out!! Thank you!!

mattias Over a year ago

A tip for the future is to debug your code, when you run into problems like this one. Then you would easily spot where the problem is.

Collectives™ on Stack Overflow

Return as String Value from For Loop Java

3 Answers 3

2 Comments

1 Comment

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

1 Comment

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related