Is Java's BigDecimal the closest data type corresponding to C#'s Decimal?

Question

According to the chart here, the equivalent data type in Java to C#'s Decimal is BigDecimal.

Is this really so? What's up with the "Big" preamble? There doesn't seem to be a "SmallDecimal" or "LittleDecimal" (let alone "MediumSizedDecimal") in Java.

I must say, though, that chart was the clearest thing I found on the subject; the other links here and here and here were about as clear to me as the Mississippi River after a torrential tempest.

Answer 1

Is this really so?

They are similar but not identical. To be more specific: the Java version can represent every value that the C# version can, but the opposite is not true.

What's up with the "Big" preamble?

A Java BigDecimal can have arbitrarily much precision and therefore can be arbitrarily large. If you want to make a BigDecimal with a thousand places of precision, you go right ahead.

By contrast, a C# decimal has a fixed size; it takes up 128 bits and gives you 28 decimal places of precision.

To be more precise: both types give you numbers of the form

+/- someInteger / 10 ^ someExponent

In C#, someInteger is a 96 bit unsigned integer and someExponent is an integer between 0 and 28.

In Java, someInteger is of arbitrary size and someExponent is a signed 32 bit integer.

Answer 2

Yep - that's the corresponding type.

Since you are using Java after C# - don't be too surprised to find little nuances like this - or be too upset when there is no easy way to do something that's "easy" to do C#. The first thing that comes to my mind is int & int? - in Java you just use int and Integer.

C# had the luxury of coming after Java so lots of (what I subjectively see as) bad decisions have been fixed/streamlined. Also, it helps that C# was designed by Andres Hejlsberg (who is arguably one of the best programming language designers alive) and is regularly "updated" unlike Java (you probably witnessed all things added to C# since 2000 - complete list)

Answer 3

The C# Decimal and java BigDecimal types are not equivalents. BigDecimal is arbitrary precision. It can literally represent any number to any precision (until you run out of RAM).

C# Decimal is floating point but "fixed length" (128 bits). Most of the time, that's enough! Decimal is much faster than BigDecimal, so unless you really need a lot of precision it is a superior option.

What you probably want for Java is https://github.com/tools4j/decimal4j or a similar library.