Performance of the Number class

I'm just wondering about the performance of the Number class as opposed to, say using generics or even a whole lot of functions to handle primitive types.

开发者_如何学C

The primitive types would clearly be the fastest option I would assume, however if the performance hit is not too huge, it would likely be easier for the coder to just use the Number class or generics rather than making a function that accepts and returns long, double (etc).

I am about to do a performance benchmark of the 3 options mentioned. Is there anything I should be aware of/try out when doing this, or even better, has someone done this before that they can give me results to?

---

Typically you use the Number class as opposed to primitive types because you need to use these values in collections or other classes that are based on Objects. If you are not restricted by this requirement, then you should use primitives.

---

Yes, there is a performance hit associated with using the Number class, in comparison with primitive types like int, long, etc. Especially if you are creating a lot of new Numbers, you will want to worry about the performance when compared with creating primitive types. But this is not necessarily the case for passing Numbers to methods. Passing an instance of Number to a method is no slower than passing an int or a long, since the compiler can basically pass a "pointer" to a memory location. This is very general information because your question is very general.

---

One thing you should be aware is that object allocation is likely to be the largest cost when you use Numbers. This affects your benchmarks as certain operations which use auto-boxing can use cached values (which don't create objects) and can give you much better performance results. e.g. if you use Integers between -128 and 127, you will get much better results than Doubles from -128 to 127 because the former uses caches values, the later does not.

In short, if you are micro-benchmarking the use of Numbers, you need to ensure the range of values you use are realistic, not all values are equal in terms of performance (of course for primitives this doesn't matter so much)