Generating random array of fixed length (Java)

Question

im just looking to change my code so that a random array of a fixed length of 100 integers is generated every time the code is ran rather than just have a pre-set array within t

Answer 1

The below would fill an array of 100 integers with Random numbers from 1-1000

int[] numbers= new int[100];
Random rand = new Random();
for (int i = 0; i < numbers.length; i++) {
      numbers[i] = rand.nextInt(1000);
}

However note that the above code might insert duplicates. If you want to avoid that, using a List in parallel to the array and checking whether the generated value already exists should ensure uniqueness :

int[] numbers= new int[100];
List<Integer> numbersList = new ArrayList<Integer>(numbers.length);
Random rand = new Random();
for (int i = 0; i < numbers.length; i++) {
    int j = rand.nextInt(1000);
    while (numbersList.contains(j)) {
        j = rand.nextInt(1000);
    }
    numbers[i] = j;
    numbersList.add(j);
}

Even though I think it would be wiser to get rid of the array and use just the List...

Answer 2

You should look at the Random class. More specifically:

1. nextInt() to fill it one by one
2. ints​(long) to get an IntStream of fixed size, which can be easily converted to an array with .toArray()

Answer 3

public class Selectionsort { 
     public static void main(String[] args) {     
        int[]numbers= new int[100]
        Random random = new Random();

       for(int i=0;i<numbers.length;i++){
           numbers[i]=random.nextInt(100);
       }
       sort(numbers); 

       printArray(numbers);
  } 

The above snippet will help you to create a random numbers between 1 to 100 for the array of size 100.