k random numbers from n

import java.util.*;
/** There is a linked list of numbers of length N. N is very large and you don't know N.
 *  You have to write a function that will return k random numbers from the list.
 *  Numbers should be completely random.
 */
public class KrandN {

    public class Number implements Comparable<Number> {
        private int value;
        Number(int v) {
            value = v;
        }
        public int getValue() {return value;}
        public String toString(){
            return ""+value;
        }
        public int compareTo(Number other) {
            return value - other.value;
        }
    }
    public class KNumber implements Comparable<KNumber> {
        private int k;
        private Number num;
        KNumber(int v, int k) {
          this.num = new Number(v);
          this.k = k;
        }
        public int getValue() {return num.getValue();}
        public int getK() {return k;}
        public String toString(){
            return "[k:"+k+","+getValue()+"]";
        }
        public int compareTo(KNumber other) {
            return k - other.k;
        }
    }

    /* traverse the list, generating a new random number for each entry.
     * remember the top k highest random numbers, and their associated entries.
     * When we hit the end of the list, the numbers in the chart are the required random numbers.
     */
    public PriorityQueue<KNumber> krandn(Vector<Number> list) {
      PriorityQueue<KNumber> p = new PriorityQueue<KNumber>();
      int size = list.size();
      System.out.println("\n\nrands for k including repeats, PriorityQueue will take care of it:");
      for (Number n : list) {
        int r=rand.nextInt(size);
        System.out.print(","+r);
        KNumber k = new KNumber(n.getValue(), r);
        p.add(k);
      }
      System.out.println("\n");
      return p;
    }

    private static final int num=152;
    private static final int maxnumk=20;
    Vector<Number> list = new Vector<Number>();

    public Vector<Number> shuffle(Vector<Number> list){
        if (list == null || list.size() < num) {
            System.out.println("\ninitialize list");
            list = new Vector<Number>(); // new list
            for (int i=0; i<num; i++) {
                Number c = new Number(i);
                list.add(c);
            }
        }
        int [] arr = new int[num];
        int j=0;
        for (Number n : list) {
            arr[j++] = n.getValue();
        }
        shuffleArr(arr);
        list = new Vector<Number>(); // new list
        for (int i=0; i<num; i++) {
            Number c = new Number(arr[i]);
            list.add(c);
        }
        return list;
    }
    Random rand = new Random();
    public void shuffleArr(int [] arr){
        for (int i=0; i<arr.length-1; i++) {
            int rnd = i+ rand.nextInt(arr.length-i);
            //swap arr[i] and a[rnd]
            int tmp = arr[i];
            arr[i] = arr[rnd];
            arr[rnd] = tmp;
        }
    }

    public static void main(String[] args) {
        KrandN inst = new KrandN();
        Vector<Number> list = null;
        list = inst.shuffle(list);
        System.out.println("\nout:");
        for (Number n : list) {
          System.out.print(","+n.toString());
        }
        PriorityQueue<KNumber> p = inst.krandn(list);
        System.out.println("\n top k list, random k elements (up to "+maxnumk+"):");
        int i = 0;
        while (!p.isEmpty() && i++ < maxnumk) { 
            KNumber n = p.remove();
            System.out.print(","+n);
        }

        //System.out.println("\nsorted:");
        //Collections.<Number>sort(list);
        //for (Number n : list) {
        //    System.out.print(","+n.toString());
        //}
    }
}

 top k list, random k elements (up to 20):
,[k:1,29],[k:2,27],[k:2,105],[k:4,23],[k:6,30],[k:7,64],[k:9,102],[k:9,8],[k:9,1
7],[k:11,82],[k:12,128],[k:13,58],[k:13,135],[k:13,145],[k:13,15],[k:14,109],[k:
16,126],[k:17,111],[k:19,37],[k:19,53]