Java: Generate random letter, return as a String

Question

I need to create a method to geneate random (single) letter and return it as String, not as a char.
I saw solutions like this creating random char. But I need my method to return a String type.
I managed to build the following method:

public static String randomLetter(){
    int num = intInRange(0, 26) + 97;
    char [] temp = new char[1];
    temp[0] = (char) num;
    return new String(temp);
}

Based on already existing method in our project

public static int intInRange(int min, int max) {
    Random rnd = new Random();
    return rnd.nextInt(max - min) + min;
}

But I do not like what I currently have since I'm creating too many temporary variables to achieve the goal.
Is there a way to get similar result in a shorter way to avoid usage of char [] temp ?

Is using `intInRange()` an absolute must? Is selecting from a prefilled array of strings an option? — Chaosfire, Jun 05 '23 at 12:24

score 2 · Answer 1 · answered Jun 05 '23 at 12:34

2

Wouldn't it be more useful to be able to return a String of any length, including 1? If so, you could do something like the following:

public static String randomString(int length) {
    return new Random().
        ints('A', 'z').
        filter(Character::isLetter).
        limit(length).
        collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append).
        toString();
}

answered Jun 05 '23 at 12:34

g00se

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I see, thank you! – Prophet Jun 05 '23 at 12:41

WJS · Accepted Answer · 2023-06-05T12:46:28.550

1

Try it like this. First cast the returned int as a char and then append "" to convert to a String.

public static String randomLetter() { 
   return (char)(intInRange('a', 'z'+1)) +"";
}

Since String.valueOf() first boxes the char to Character and then calls String.valueOf() on that object, I would just call Character.toString() directly and avoid the extra overhead.

public static String randomLetter() {
    return  Character.toString(intInRange('a', 'z'+1));
}

edited Jun 05 '23 at 12:46

answered Jun 05 '23 at 11:54

WJS

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Thank you for your answer, but I think the solution suggested by @0x150 is clearer. Satyajit Bhatt detailized that. +1 – Prophet Jun 05 '23 at 12:45
@Prophet, read my updated answer. Just use Character.toString(); – WJS Jun 05 '23 at 12:46
Well, this sound even better, I see. Thanks a lot! – Prophet Jun 05 '23 at 13:03
To be honest, the delta on overhead is there but negligible so any of the answers, imho, are acceptable. – WJS Jun 05 '23 at 13:05
Agree with you again :) – Prophet Jun 05 '23 at 13:16

Java: Generate random letter, return as a String

2 Answers2