Question

I know about the JAVA Random class and its use. But I want to generate a random number which should not be repeated until all the numbers in the range are generated at least once. Can anybody provide me some reference..?

While using the Random class, the problem I face is that some numbers get repeated 2 or 3 times while some are not generated at all.. My application may fail in this scenario as I have another thread processing some requests based on the numbers getting generated….and the moment there is a delay and next unique digit is not available, it stops without processing the non – generated numbers…

Answer 1

You can generate all the values in range and shuffle them. Collections.shuffle() Once you have uses every value, repeat.

Imagine you have decks of cards, You take one deck which has a every card once, you shuffle it and you will know what while each card will come in a random order, only once. When one deck has finished you take all the cards again and reshuffle (or a new deck and shuffle that)