Get N random elements from list without shuffling whole list.

Util.java

public class Main {
    
    /**
     * Returns new list of N random elements from provided list.
     * 
     * @param list list of elements to choose from
     * @param n    number of elements to choose
     * @param <E>  type of elements in a list
     * @return     new list of N random elements from provided list
     */
    public static <E> List<E> getNRandomElementsFromList(List<E> list, int n) {
        int listLength = list.size();
        Random r = new Random();

        if (n >= listLength) return list;

        // Collections.shuffle algorithm (Fisher-Yates shuffle) that is stopped
        // after acquiring needed number of random elements
        for (int i = listLength; i > listLength - n; i--)
            Collections.swap(list, i - 1, r.nextInt(i));

        return list.subList(listLength - n, listLength);
    }
    
    private static void print(float[] array) {
        for (float i: array) System.out.print(i + " ");
        System.out.print("\n");
    }
    
    // Driver code to test probability of each element to appear in results.
    public static void main(String[] args) {
        
        ArrayList<Integer> arrayList = new ArrayList<>(Arrays.asList(0,1,2,3,4,5,6,7,8,9));
        List<Integer> nRandom = new ArrayList<>();

        float[] results = new float[10];
        int runs = 1000000;
        for (int i = 0; i < runs; i++) {
            nRandom = getNRandomElementsFromList(arrayList, 5);
            for (int e: nRandom) results[e]++;
        }

        for (int i = 0; i < results.length; i++) results[i] /= runs;
        print(results);
    }
}