random unique number in java

Question

I'm trying to get a a list of random number and put it in queue without any repetition of the random number.

        int number = 40;

        for (int j = 0; j<number; j++)
        {
            int pick = random.nextInt(number);
            myQueue.add(Integer.toString(pick));
        }
        System.out.println("the queue size: "+myQueue.size());
        Iterator it = myQueue.iterator();
        while(it.hasNext()){
                String iteratorValue = (String)it.next();
                System.out.println("queue next value: "+iteratorValue);
        }

with the above code, I got some repetition of the random number

anyone know how to do it??

Answer 1

How about this:

List<String> list = new ArrayList<String>(number);

for (int i = 0; i < number; i++)
    list.add(Integer.toString(i));

Collections.shuffle(list);

myQueue.addAll(list);

"Adding unique random numbers" in some range is equivalent to adding all of the numbers in the range and then shuffling the result.