Any filter-like lambda operation which does not discard?

Question

I basically would like to do something like:

  assertEquals(Arrays.asList(1,2,3).stream()
                                   .noDiscardingFilter(x -> x!=1         


        

Answer 1

If you want to only change the entries which match the filter but retain the rest.

assertEquals(Arrays.asList(-1, 1, 20, 30),
             Stream.of(-1, 1, 2, 3)
                   .map(i -> i <= 1 ? i /* retain */ : 10 * i /* transform */)
                   .collect(Collectors.toList()));