[FIXED] IntelliJ doesn't infer Stream.collect() type result

Issue

This code works on Netbeans but gives an error on IntelliJ:

public static List<String> readFile(String file) throws IOException {
   Path path = Paths.get("src", file);
   Stream<String> lines = Files.lines(path);
   return lines.collect(Collectors.toList());
}

The error is on the return statement and says that a List<String> is expected but the collect() method gives a List<Object>. It looks like that Netbeans is able to understand that a Stream<String> must be collected to a List<String> while IntelliJ isn't.

What's the problem here?

EDIT: As suggested, I upgraded IntelliJ to the latest version (14.1.1) and I tried to compile my code with javac by terminal: it works. The problem must be in my IntelliJ configuration but it looks correct to me

Solution

I solved the mistery: in File Menu->Project Structure, change Project Language Level to 8.0 - Lambdas, type annotations etc.

Answered By - Oneiros