Your logic is incorrect. I've added a line printing out
i when it's added to the List, and it adds all numbers multiple times. I stopped it at 15 which isn't even a prime number.
Your mistake is that you think that a number is a prime if it's not a multiple of one single previously found prime. Instead, a number is a prime if it's not a multiple of
all previously found primes. And
you should also not start at 1 but 2 instead, or you will end up with only one "prime number": 1.