generate random number and store to array then check of the same new random

Question

I generated 1-10 random numbers and stored it in an array. My question is how I'm going to code this first, random three times if 2 or all of them are duplicates then random again three times and if they are different from each other then save to the array. so here's my code:

CODE:

int min=1;
int max=10;
int y=0;

Random rand = new Random();

for(int count=0;count<1;count++){
   int randomNum = rand.nextInt((max - min) + 1) + min;
   arr[count] = randomNum;
}
System.out.println(arr[0]);//for checking
System.out.println(randomNum);//for checking

You want to check for duplicates? duplicates followed by each other? Rephrase please — anaxin, Feb 20 '16 at 08:38
if (arr[0] != randonNum) is the answer to your question. If you wanted for n values you should have asked that. — anaxin, Feb 20 '16 at 08:47

score 0 · Answer 1 · edited May 23 '17 at 11:45

0

You can check if the array contains this random number.

Arrays.asList(arr).contains(randomNum)

If it doesn't then you add it in the array, otherwise you throw an exception or ignore in depends what your logic is.

Similar question I think: How can I test if an array contains a certain value?

edited May 23 '17 at 11:45

Community

1
1

answered Feb 20 '16 at 08:43

Nick

156
1
11

score 0 · Answer 2 · answered Feb 20 '16 at 08:45

0

public boolean checkArray(Int[] arr, Int targetValue) {
    for(Int i: arr){
        if(i == targetValue)
            return true;
    }
    return false;
}

answered Feb 20 '16 at 08:45

dijam

658
1
9
21

Maybe add a little explanation as to how and why this works? – Benjamin W. Feb 21 '16 at 00:22

score 0 · Answer 3 · answered Feb 20 '16 at 11:48

I think this is what you're looking for :

public static int[] generatePureRandomIntegers(int n) {
    final int[] array = new int[n];
    for (int i = 0; i < n; i++) {
        array[i] = i + 1;
    }
    final Random random = ThreadLocalRandom.current();
    for (int i = array.length; i > 1; i--) {
        swap(array, i - 1, random.nextInt(i));
    }
    return array;
}

private static void swap(int[] array, int i, int j) {
    int tmp = array[i];
    array[i] = array[j];
    array[j] = tmp;
}

create a new array of ints and fill it from 1 to n then shuffle the array.

for example :

int[] randomNumbers = generatePureRandomIntegers(10);
System.out.println(Arrays.toString(randomNumbers)); // [4, 6, 5, 7, 1, 10, 8, 9, 2, 3]

generate random number and store to array then check of the same new random

3 Answers3