java - How to have unique random number?

Question

This is how i am generating a unique no in between 1 to 6 and getting appropriate images from the drawable folder.

Random rand = new Random();
// n = the number of images, that start at idx 1
rndInt = rand.nextInt(6) + 1; 
String imgName = "card" + rndInt;
int id = getResources().getIdentifier(imgName, "drawable", getPackageName());
imgView.setImageResource(id);

What i want is, I have to call this method 7 times, and each time this method should return a unique random no. so that none of the already chosen numbers will come up again.

Answer 1

The usual approach to this kind of problem is to create a list containing each of the possible values and shuffle it (use Collections.shuffle). You then consume one item from the list each time you need a value. This will ensure that you don't use the same value more than once but still allows for a random order.