Subtraction of System.currentTimeMillis()

Question

    long rt = System.currentTimeMillis()-(1000*60*60*24*30);

When i convert the above variable rt to date i am not able to get expected date(i.e)30 days before. why?

Answer 1

1000*60*60*24*30 results in int overflow, since it's larger than Integer.MAX_VALUE. Change it to 1000L*60*60*24*30 to use long instead.

For example:

long rt = System.currentTimeMillis()-(1000L*60*60*24*30);
System.out.println (new Date(rt));

prints for me:

Sun Feb 25 09:18:58 IST 2018