ArrayList. Boxing perfomance?

Question

I'm writing an application which will process a large amount of data and I need an ArrayList<Integer> functionality. I want to rewrite ArrayList class in order to work with an int type, instead of an Integer class. How much will this improve performance?

No idea but you could probably rewrite the class fairly quickly and test it. (Most likely just a couple of search and replaces and remove the generics) — FDinoff, Aug 17 '13 at 15:13
It entirely depends on *how* you use the `ArrayList`. Also, there are already implementations for "primitive" collections, such as fastutil. — mikołak, Aug 17 '13 at 15:13
possible duplicate of [Integer auto-unboxing and auto-boxing gives performance issues?](http://stackoverflow.com/questions/6037389/integer-auto-unboxing-and-auto-boxing-gives-performance-issues) — SJuan76, Aug 17 '13 at 15:13
Please do a minimal effort before posting. Just googling "java autoboxing performance" gives you lots of information. — SJuan76, Aug 17 '13 at 15:14
see this for a stopwatch class which can be used to find which class is faster http://stackoverflow.com/questions/8255738/is-there-a-stopwatch-in-java (note:stopwatch is not 100% accurate) — bhathiya-perera, Aug 17 '13 at 15:15

dantuch · Accepted Answer · 2013-08-17T15:26:54.617

4

Don't reinvent the wheel.

It was done long time ago :)

http://trove4j.sourceforge.net/javadocs/gnu/trove/list/array/TIntArrayList.html

it works great.

benchmarks

edited Aug 17 '13 at 15:26

answered Aug 17 '13 at 15:17

dantuch

9,123
6
45
68

No problem, I'm using Trove myself for the same reason - big amount of data that's needs to be stored in memory. – dantuch Aug 17 '13 at 15:30

score 0 · Answer 2 · answered Aug 17 '13 at 15:19

0

ArrayList<int[]> arlist=new ArrayList<int[]>();
int ar1[]={1,2,3};
arlist.add(0,ar1);

Isnt this plausible?

answered Aug 17 '13 at 15:19

Jebathon

4,310
14
57
108

Not really :-) That's not functionally equivalent to a list of Integer. – Stephen C Aug 17 '13 at 15:28

score 0 · Answer 3 · answered Aug 17 '13 at 15:26

You don't need to do this. See @dantuch's Answer.

I just want to point out the problems with using a specialized "list of int" class.

The class cannot be API compatible with the standard collection classes and interfaces. If you are trying to use some other API that requires a Collection or a List, then the specialized class cannot be used with it.
You won't be able to use polymorphism across the various "list of primitive" types.

ArrayList. Boxing perfomance?

3 Answers3