@Test public void forEachInBoth() { final MutableList<Pair<String, String>> list = Lists.mutable.of(); ArrayList<String> list1 = new ArrayList<String>(mList("1", "2")); ArrayList<String> list2 = new ArrayList<String>(mList("a", "b")); ArrayListIterate.forEachInBoth( list1, list2, new Procedure2<String, String>() { public void value(String argument1, String argument2) { list.add(Tuples.twin(argument1, argument2)); } }); Assert.assertEquals(FastList.newListWith(Tuples.twin("1", "a"), Tuples.twin("2", "b")), list); }