Use Java for loop and create variable from output [duplicate]

Question

I'm trying to make a variable out of the result of a for loop. First of all is this possible? If it is possible how do i do it? This is my code so far:

Random r = new Random();
Random n = new Random();

int p = (int)(n.nextInt(14));

for (int i = 0; i < p; i++) {
  char c = (char) (r.nextInt(26) + 'a');
  System.out.println(c);}

  String word = ("output of forloop goes here");

I want to put all the randomly generated letters into one word using the for loop. How do I do this?

don't use System.out.println, but maybe the StringBuilder ? docs.oracle.com/javase/7/docs/api/java/lang/StringBuilder.html — dognose
– dognose, Commented Jul 23, 2014 at 18:18
What's wrong with creating a String/StringBuilder outside the loop and appending the generated characters to it inside the loop? — Timo Geusch
– Timo Geusch, Commented Jul 23, 2014 at 18:18
You got an answer but you don't show any effort trying to do it yourself. Pity. — Jonathan Drapeau
– Jonathan Drapeau, Commented Jul 23, 2014 at 18:28

Eran · Accepted Answer · 2014-07-23 18:18:08Z

5

Use StringBuilder :

StringBuilder sb = new StringBuilder();
for (int i = 0; i < p; i++) {
  char c = (char) (r.nextInt(26) + 'a');
  sb.append(c);
}

Then you can call sb.toString() to get the resulting String.

answered Jul 23, 2014 at 18:18

Eran

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5 Comments

AdamMc331 Over a year ago

This will work, but you don't necessarily need to use StringBuilder. You could declare a string before the loop: String output = "" and then instead of writing sb.append(c) you could write output += c

Suresh Atta Over a year ago

@McAdam331 nope. please don't do that :) evil.

AdamMc331 Over a year ago

Why is that evil? I've always used that approach.

Eran Over a year ago

@McAdam331 That would cause a construction of a new String object in each iteration, since String is immutable. Though the compiler might optimize it into a StringBuilder.

AdamMc331 Over a year ago

Oh, I never realized that's what was happening. Actually, @Eran, after you mentioned that I did a little search and according to this post the compiler can't optimize to a Stringbuilder inside of a loop, but typically will otherwise. Thanks for the insight!

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