What does division by 1e9d mean?

Question

This is the snippet:

String myTime = someTime / 1e9d + ",";

someTime is derived by using System.nanoTime(). What does 1e9d do here?

It's in nano second, so you'll have 1 000 000 000 ns every 1 second. If you want to display the time in plain seconds, you'll have to divide it by 10e9 — Fabinout, Dec 12 '13 at 16:05

score 10 · Accepted Answer · edited Jun 16 '19 at 01:41

10

1e9 means 10^9
2d means 2 as double

e.g.

sysout 1e9 => 1.0E9
sysout 10e9 => 1.0E10

See also the Floating-Point Literals section of The Java™ Tutorials.

edited Jun 16 '19 at 01:41

Adrian

3,321
2
29
46

answered Dec 12 '13 at 16:05

Georgian

8,795
8
46
87

How will I express 1.0e-3 on the same lines? '1e-3d'? It doesn't give me any error. – user1071840 Dec 12 '13 at 16:55
@user1071840 Or simply `1e-3` – Georgian Dec 12 '13 at 16:57

Eyal Schneider · Answer 2 · 2013-12-12T16:21:55.980

2

The suffix d denotes a double number. If the number wasn't treated as a floating point number, then the division would be considered an integer division, returning an integer (e.g. 3/2=1).

1e9 is simply 10^9. The conversion seems to be from nanoseconds to seconds.

--EDIT--

Ingo correctly points out that 10e9 is already evaluated by java to a double (see this part of the spec for details). Therefore the 'd' isn't needed in this case.

edited Dec 12 '13 at 16:21

answered Dec 12 '13 at 16:09

Eyal Schneider

22,166
5
47
78

You should perhaps add that the notation `10e9` is already enough to establis that it is a double, at least in Java. Hence the `d` suffix is really superfluous here. – Ingo Dec 12 '13 at 16:17

What does division by 1e9d mean?

2 Answers2