Java interop - accessing inner classes

[Paul Butcher]

I can't help but think that I'm being dumb, but I just can't work out how to access an inner class implemented in Java :-(

Given the following Java:

> public class Foo {
> public class Bar {
> Bar() {}
> }
>
> public Bar getBar() { return new Bar(); }
> }

I get:

> scala> val f = new Foo
> f: Foo = Foo@756a7c99
>
> scala> val b = new Foo.Bar
> <console>:5: error: type Bar is not a member of object Foo
> val b = new Foo.Bar
> ^
>
> scala> val b = f.getBar
> b: Foo#Bar = Foo$Bar@3cecfaea
>
> scala> val b2 = new Foo#Bar
> <console>:5: error: Foo is not a legal prefix for a constructor
> val b2 = new Foo#Bar
> ^

What am I missing?

(note that I'm aware of the "Scala can't access a static inner class" issue. But this isn't a static inner class).

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[Nate Nystrom]

scala> val f = new Foo

f: Foo = Foo@3ee969f8

scala> new f.Bar
res1: f.Bar = Foo$Bar@53e36ec6

Foo#Bar is a supertype of f.Bar, but it's not a class, so you can't instantiate it. I had to make the Bar constructor public to avoid an IllegalAccessError.

Nate

[thomas rimmele]

This is not a scala problem. Pure Java:

public class Foo {
    public class Bar {
        Bar() {
        }
    }

    public Bar getBar() {
        return new Bar();
    }
   

    public static void main(String[] args) {
        System.out.println(new Foo().getBar());
        System.out.println(new Bar()); // ERROR
    }
}


To say it with the words of eclipse:
   No enclosing instance of type Foo is accessible. Must qualify the allocation with an enclosing instance of type Foo (e.g. x.new A() where x is an instance of Foo).

Greetings, Thomas

[Paul Butcher]

On 12 Mar 2011, at 10:44, Nate Nystrom wrote:
> Foo#Bar is a supertype of f.Bar, but it's not a class, so you can't instantiate it. I had to make the Bar constructor public to avoid an IllegalAccessError.

D'oh! I knew I was being dumb. Thanks!