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Editorial Team
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Asked: 2026-05-25T16:48:12+00:00

Wow! I have just realized that varargs methods in Java cause an array to

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Wow! I have just realized that varargs methods in Java cause an array to be allocated when they are called. Not sure why I would expect anything different, but should there perhaps be some kind of pooling for the arrays? At least for the initial 0 to 8 sizes? Is there any workaround in Java to use varargs without causing an array allocation for every call?

EDIT: Please understand that leaking memory to the GC is just an unwanted overhead/latency. It is NOT a bug like some comments implied. Just because Java has GC does not mean you can create tons of garbage at will.

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  1. Editorial Team

    See the example of EnumSet. the vararg method 

    of(E first, E... rest)

    is overloaded with 

    of(E e1, E e2) 
of(E e1, E e2, E e3) 
of(E e1, E e2, E e3, E e4) 
of(E e1, E e2, E e3, E e4, E e5)

    to avoid the vararg array creation if args are 5 or less. (EnumSet probably goes too far here)

    I don’t think this is really a GC concern. The array created is dereferenced very quickly, such die-young garbage should have almost no impact to GC.

    However, instantiating an array is a relatively expensive operation; since EnumSet.add() is very fast, the overhead of array creation can be quite noticeable; they probably did some benchmark, and decided it’s worthwhile to optimized with overloading for up to 5 args.

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