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?

Flam

10^9 as a double (kind of redundant). – Incommutable

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 – Placard

1e9d is scientific notation – Intoxicated

Answer 1

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.

Inkster

How will I express 1.0e-3 on the same lines? '1e-3d'? It doesn't give me any error. – Flam

@Flam Or simply 1e-3 – Inkster

Answer 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.

Ethmoid

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. – Trappings