System.currentTimeMillis(); If I change system time

Question

If I use System.currentTimeMillis() at 00:00 and I get X value.

Then I set the clock back one hour, and after one hour i call System.

Answer 1

It will return X because System.currentTimeMillis() returns the number of milliseconds since the epoch. That means it will be insynch with your clock and count the number of seconds since January 1, 1970 UTC

Answer 2

In a nutshell, whenever you change system time, the value returned by System.currentTimeMillis() will change accordingly.

This is in contrast to System.nanoTime().

Answer 3

On Android, you can always use SystemClock.elapsedRealtime().