java - Consistent use of primitives and wrapped primitives -

if use int specific variable, have deal kind of collection it, means int converted wrapped int/int object , vice versa many times, makes sense in case, performance-wise , semantically better use integer variable, avoid constant casting between int , integer (i.e. when add int collection, have casted integer (actually have newly created), , when collection, have casted int)?

to consistent, there 2 possibilities here:

• either use wrapper classes time

• or use primitive collections (e. g. commons primitives)

but if don't have special case here , tracked performance issues down casting, performance impact of casting negligible here. should not worry such micro optimizations if don't need to.

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using wrapper classes not bring benefit, too. think following code:

list<integer> numbers, squares;     //initialize both, fill numbers      for(integer number: numbers)         squares.add(number*number);      for(int i: numbers) {         squares.add(i*i);     } 

in first loop, number straigt collection without casting, casted int, multiplied itself, , autoboxed integer before storing in squares.

in second loop, convert integer int when fetching list, multiply itself, , autobox integer before storing it.

in both cases, have autoboxing involved. avoid this, had use primitive collections, or int[].