java.time

I should like to contribute the modern answer.

    String ts = String.valueOf(Instant.now().getEpochSecond());
    System.out.println(ts);

Output when running just now:

1543320466

While division by 1000 won’t come as a surprise to many, doing your own time conversions can get hard to read pretty fast, so it’s a bad habit to get into when you can avoid it.

The Instant class that I am using is part of java.time, the modern Java date and time API. It’s built-in on new Android versions, API level 26 and up. If you are programming for older Android, you may get the backport, see below. If you don’t want to do that, understandably, I’d still use a built-in conversion:

    String ts = String.valueOf(TimeUnit.MILLISECONDS.toSeconds(System.currentTimeMillis()));
    System.out.println(ts);

This is the same as the answer by sealskej. Output is the same as before.

Question: Can I use java.time on Android?

Yes, java.time works nicely on older and newer Android devices. It just requires at least Java 6.

• In Java 8 and later and on newer Android devices (from API level 26) the modern API comes built-in.
• In non-Android Java 6 and 7 get the ThreeTen Backport, the backport of the new classes (ThreeTen for JSR 310; see the links at the bottom).
• On (older) Android use the Android edition of ThreeTen Backport. It’s called ThreeTenABP. And make sure you import the date and time classes from org.threeten.bp with subpackages.

Links