strange behavior of long data type

Question

I have problem with the Long data type when I run this command:

Long nanos = 3 * 1000000000
println nanos

It prints out -1294967296, not 3000000000, and I dont know why.
I read on this page that Long is enough. So what is wrong ?

Answer 1

You must mark your 2nd constant as long, otherwise it's considered an integer which overflows. Use:

Long nanos = 3 * 1000000000L

Answer 2

You need to add a suffix to literals to imply that they are long values. Otherwise they are interpreted as int.

  Long nanos = 3 * 1000000000L;

More info about this here.