Random numbers between my own values

Question

I'm writing a program that generates co-primes of a number.

Now for example a number 'A' has 50 co-primes, my objective is to randomly select a co-prime from the list of all co-primes generated for the number A.

Again for example: consider a number 15, it has co-primes - {1, 2, 4, 7, 8, 10, 11, 13, 14}. So now i have to select randomly from these values. Likewise, if i generate an array of any values, then how to randomly select from this array.

So in general my question is how to generate a random number from the array of numbers that i have. Now, those numbers in the array can be anything. Like not necessarily natural numbers, or prime numbers, etc.

So is there any java function to do so. I've burnt my brain searching the internet, but didn't find one. I usually go for finding result on google, rather than asking quetions on forums. But when one gets exhausted, it's better to ask experts out there who might have faced similar problems.

Thanks in advanced!!

Answer 1

Is that what you want ?

int[] arr = { 1,5,9,3,2,7 };
Random rd = new Random();
int dice  = arr[rd.nextInt(arr.length)];

Answer 2

You can use the java.util.Random class for this:

public int chooseRandom(int[] coPrimes) {

    //Creates the Random instance
    Random randomizer = new Random();

    //Generate a random integer between 0 and the length of the array (exclusive)
    int value = randomizer.nextInt(coPrimes.length);

    //Return the element at that generated index
    return coPrimes[value];
}