Thank you all for your replies!
I'm aware of the workaround (we are using this approach in our project) and
the problematic issues with decimal conversions. However, I also think that
we should make sure that the behaviour of the code is more predictable. For
me and other developers, it might be confusing that values of *new
BigDecimal(Float.toString(val))*, and then *BigDecimal.valueOf(double val)* are
different. I'd say that, if it's possible, we should reduce the arithmetic
artifacts, rather than introduce them through not really needed, and not
visible at the first sight, type conversions.
Unfortunately, I was aware about potential backwards compatibility issues
and I was curious what is your opinion on this (I also thought about
introducing a factory method like fromFloat to eliminate it, but I'm not
sure if it sounds like a good idea). Do you think introducing such change
would be beneficial to simplify the code, or rather introduce minor
precision improvement, while we still don't have 100% decimal precision?
Also out of curiosity I ran a benchmark on how lack of this constructor
impacts performance, and it seems like type conversion makes it around 7
times slower, than direct Float usage
@Benchmark
public void oldApiFloat(Blackhole blackhole) {
for (int i = 0; i < iterations; i++) {
blackhole.consume(BigDecimal.valueOf(0.1f));
}
}
@Benchmark
public void newApiFloat(Blackhole blackhole) {
for (int i = 0; i < iterations; i++) {
blackhole.consume(valueOf(0.1f));
}
}
public static BigDecimal valueOf(float val) {
return new BigDecimal(Float.toString(val));
}
Benchmark (iterations) Mode Cnt
Score Error Units
BigDecimalBenchmark.newApiFloat 1000 thrpt 25 28355,359 ±
502,195 ops/s
BigDecimalBenchmark.newApiFloat 2000 thrpt 25 14132,275 ±
206,593 ops/s
BigDecimalBenchmark.newApiFloat 5000 thrpt 25 5667,007 ±
71,941 ops/s
BigDecimalBenchmark.newApiFloat 10000 thrpt 25 2808,114 ±
32,403 ops/s
BigDecimalBenchmark.newApiFloat 100000 thrpt 25 278,405 ±
4,642 ops/s
BigDecimalBenchmark.oldApiFloat 1000 thrpt 25 3559,235 ±
40,931 ops/s
BigDecimalBenchmark.oldApiFloat 2000 thrpt 25 1782,190 ±
21,805 ops/s
BigDecimalBenchmark.oldApiFloat 5000 thrpt 25 712,045 ±
6,495 ops/s
BigDecimalBenchmark.oldApiFloat 10000 thrpt 25 355,959 ±
6,006 ops/s
BigDecimalBenchmark.oldApiFloat 100000 thrpt 25 36,239 ±
0,423 ops/s
pt., 24 sty 2025 o 00:59 Joseph D. Darcy <joe.da...@oracle.com> napisał(a):
> On 1/23/2025 2:35 PM, Remi Forax wrote:
>
> Hello Jan,
> what you are suggesting is not a backward compatible change.
>
>
> There is a source compatibility impact, meaning that for some call sites,
> the mapping of existing code using BigDecimal before and after the addition
> of the overloaded method would change. That wouldn't necessarily preclude
> us from making such a change (and such changes have been made in the past),
> but extra caution and analysis would be called for.
>
> Cheers,
>
> -Joe
>
>
>
> If we add BigDecimal,valueOf(float), then a program recompiled with the
> new JDK may change its behavior,
> you can think that the new behavior is more "correct" that the current
> one, but changing the behavior of existing programs is usually a big NO !
> in Java.
>
> Also, I believe that the reason there is no such factory method that takes
> a float is that doing computations on floats is not recommanded, it becomes
> a mess rapidly of the imprecision of the float32 representation, .
> For the same reason, in Java, 2.0 is a double and there is no FloatStream
> while there is a DoubleStream.
>
> regards,
> Rémi
>
> ------------------------------
>
>
