Collectors::toList cyclic inference

Question

In the following code Intellij says "Cyclic inference"

List<String> rows = new ArrayList<>();
rows.add("12345");
rows.add("123");
rows.add("123456");
rows = rows.stream().filter(e -> e.length() > 4).collect(Collectors::toList);
rows.stream().forEach(System.out::println);

There must be some problems with Collectors::toList which I can't uderstand.

Answer 1

collect expects Collector which is not functional interface so you can't use lambda or method reference to provide its implementation.

You simply need to use Collectors.toList() which returns Collector instance which collects your elements in list.