Efficient loop through Java List

Question

The following list is from the google I/O talk in 2008 called \"Dalvik Virtual Machine Internals\" its a list of ways to loop over a set of objects in order from most to least e

Answer 1

Third variant is faster then 7 because array is reified type and JVM should just assign a pointer to a correct value. But when you iterate over a collection , then compiler can perform additional casts because of erasure. Actually compiler insert this casts to generic code to determine some dirty hacks like using deprecated raw types as soon as possible.

P.S. This is just a guess. In fact, I think that the compiler and JIT compiler can perform any optimisation (JIT even in runtime) and result can depend on particular details like JVM version and vendor.