Stream.findFirst different than Optional.of?

Question

Let\'s say I have two classes and two methods:

class Scratch {
    private class A{}
    private class B extends A{}

    public Optional getItems(List&         


        

Answer 1

The issue you have is with inheritance for generics. Optional< B > doesn't extend Optional< A >, so it can't be returned as such.

I'd imagine that something like this:

public Optional getItems( List items){
    return items.stream()
        .map(s -> new B())
        .findFirst();
}

Or:

public Optional getItems( List items){
    return items.stream()
        .map(s -> new B())
        .findFirst();
}

Would work fine, depending on your needs.

Edit: escaping some characters