JMock Expectations, iterating through List

I have a list with Strings:

final List<String> serialNumbers=new ArrayList<String>();

for(int i=0;i<numberOfPieces;i++){
     serialNumbers.add(Integer.toString(i));
}

Now I want my MockObject to return the next element in the List as a String everytime the mock method is called, how do I do this?

context.checking(new Expectations(){{
     exactly(numberOfPieces).of (myMock).getSerialNumber();
     // will return serialNumbers i-th element
}});