How to refactor a lambda expression to a method reference?

Question

My code looks like this:

class A {
    public void m() {
        Arrays.stream("a", "b")
            .map(x -> x + "!") // <-- lambda expression
            .forEachOrdered(System.out::println);
    }
}

I want to refactor it into:

class A {
    public void m() {
        Arrays.stream("a", "b")
            .map(this::t) // <-- method reference
            .forEachOrdered(System.out::println);
    }

    public String t(String x) {
        return x + "!";
    }
}

How can I do this refactoring with IntelliJ?

Answer 1

Select the lambda, press Alt+Enter, click "Extract to Method Reference".

Answer 2

First, do the refactoring extract method on x + "!" code. Then use quick-fix replace with method reference.