How can I parallelize the mapping of a list?

Question

This is the problem I have: I have a large sequence of some objects (List<SomeClass>), and want to perform some operation on all elements of list and get a new sequence (List<SomeOtherClass>).

Like:

List<SomeOtherClass> list = new ArrayList<SomeOtherClass>();
for(SomeClass sc : originalList) 
  list.add(someOperation(sc));

Since operation someOperation does not have any side effects, and the list is quite large, I want this mapping operation to be parallelized.

What will be the best way to do that in Java?

Answer 1

A possible implementation can utilize the Executor framework (example included).

Answer 2

Use threading and partition your work using sublists.

Answer 3

Split the input list, and use FutureTask task, then merge the results