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javacollectionsperformance-testingprimitiveautoboxing

Performance implications of autoboxing on ArrayList of primitive wrappers

Java does not let us create ArrayList of primitives directly. But we can create a ArrayList of the primitives wrapper class.

But when accessing the primitive value , compiler automatically does the wrapping and unwrapping. Is this not an overhead ? My question is what are performance implications of this ?

In such a case wouldn't int[] perform better than ArrayList<Integer> ?

Has anyone measured performance of int[] vs ArrayList<Inetger> for Java5.0 (when this was first introduced) and latter versions of Java. It would be really helpful for everybody who runs into this question , if you could share the test results.

Solution

  • Indeed it adds some overhead. If it is a problem for you, consider using some library supporting collections of primitives out of the box. For example Trove, Guava or google for another library