I use Kotlin `1.3.11`

# announcements

[Tristan Caron]

I use Kotlin 1.3.11

[Czar]

1) Please use threads or edit original message when describing same issue.
2) Double is not suited for financial calculations, you cannot get precise numbers. See this answer here: https://stackoverflow.com/a/3730249/663012

[Tristan Caron]

1/ I apologise for that;
2/ It looks interesting, thank you. Somehow it reminded me something about fixed point.

[Tristan Caron]

I changed everything into BigDecimal but the result is still the same.

[Czar]

can you post a piece of code I can run to reproduce?

[Czar]

Unless whole JVM is horribly broken it should work 🙂

[Czar]

Note, I intentionally used your approach to make my code similar to yours, usually with BigDecimals you would write something like:
val totalHt = items.fold(BigDecimal.ZERO, BigDecimal::add)

[Tristan Caron]

Yes, exactly.

Even the number are not correct. It should not be 4296.5999999999 but 4296.6 because I only have 1 item with price = 0.6 and quantity = 7161

Thanks for the tip, I use BigDecimal.ZERO 🙂

[Czar]

unless you start with a Double what you are describing should be impossible

[Czar]

I mean you're probably initializing BigDecimal with a Double, check this screenshot

[Tristan Caron]

This what's happening. I can't even use breakpoints correctly.

You may have found something. But when I use my rounding function, it should work no?

Screen Recording 2019-01-17 at 20.47.13.mov

[Czar]

No, it should not, there is no way for a double to represent something like a mathematical 0.6 precisely.

[Czar]

the nice rounded numbers you see during debugging is just eye candy.

[Czar]

Using floats or doubles for finance is like a mortal sin for a developer 😄 These types just are not designed to work like we need them to for financial stuff, for some other stuff too if you believe the military anecdote in this article: https://dzone.com/articles/never-use-float-and-double-for-monetary-calculatio

[Czar]

And here's more in-depth information from Oracle: https://blogs.oracle.com/corejavatechtips/the-need-for-bigdecimal (linked from the dzone article above)

[Tristan Caron]

Well I am lucky that it's not prod yet 😄

I am getting the value from a mongodb collection, and the values are numbers. That might be why my BigDecimal are acting like this.

[Tristan Caron]

Thanks a lot for you help. I think I have my solution.

[Czar]

Yeah, with MongoDB you must use strings, it does not have dedicated decimal type beyond float/double

[Czar]

I don't know what you're using for mapping, but e.g. Spring Data MongoDB supports Java/Kotlin BigDecimal <-> BSON String mapping

[Czar]

Oh, actually it seems MongoDB 3.4 did add a suitable decimal type: https://docs.mongodb.com/manual/tutorial/model-monetary-data/#numeric-decimal Check if your mapper supports it, or use strings.

[Tristan Caron]

By the way, how did you do to display the values on the side (from your screenshot)

[Shawn]

That looks like maybe the output of a scratch file run in worksheet mode (i.e. using the big play button in the top left of the scratch editor)

[Tristan Caron]

Well I converted everything into Decimals, it still not working... Even this dirty code like

val totalTtc = decimalFormat.format((totalHt + (totalHt / 100) * invoice.taxPercent).toString().let {
                it.substring(0, it.indexOf(".") + 4)
            })

[Tristan Caron]

I am becoming crazy...

I've added logging, they do not appear. I raised an exception in the middle of my code, to make crash my app on purpose, nothing happen, it's just continuing like if it was not there.

[Shawn]

Are you rebuilding and actually running the newly built code?

[Tristan Caron]

When I do changes and click on the little bug, is it not supposed to rebuild?

[Shawn]

Ahh I think I know what’s happening

[Shawn]

hitting the button is launching a new debug session and you might be still interacting with an old one

[Tristan Caron]

Yep, you are right, I ran it using the terminal and it's now working 🙂

[Shawn]

What version of IntelliJ are you running?

[Tristan Caron]

2018.3.2

[Shawn]

they changed the default behavior from allowing sessions to run in parallel to disallowing that

[Shawn]

oh huh

[Shawn]

you might want to check in the run configuration to see if “Allow running in parallel” is enabled? Do you get a warning when you try to restart a debugging session?

[Tristan Caron]

It is not enabled