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Question

Create a playlist in iTunes with COM and Java

Answer 1

+1 A:

I havent done any iTunes stuff in Java for a while, but from what experience I have I remember that the interface can be rather fickle.

I don't have any definitive answer, but in attempt to provide at least a shot in the dark, maybe you should try casting the ITPlaylist you're working with to an ITUserPlaylist (if that's the correct type, of course) and then calling its addTrack method. That way you'd be using the function provided by the library, and if that doesn't work you can get in touch with the developer because there may be a more serious problem occurring.

From the dump you provided, it looks as though the underlying C in JACOB is trying to modify the equivalent ITPlaylist via the iTunes COM interface. This could be because of the way the inheritance is working? IE: ITPlaylist doesn't support addTrack (the underlying C is trying to call a nonexistent function) but ITUserPlaylist does? Just a thought.

Suggested correction:

public void addTrack(ITTrack track) {
    ITPlaylistKind k = getKind();
    if (k == ITPlaylistKindUser) {
        Dispatch.put( ((ITUserPlaylist)this).object, "AddTrack", track);
    } else
        throw new UnsupportedOperationException("can only add track to user playlists - kind : " + k);
}

Again I'm certainly not the expert here so if anyone has any better ideas, please go ahead and post over me :)

Let me know if that offers you any success!

Edit After re-reading my post, I realized I forgot this approach, which could arguably be better as it keeps the JACOB COM bridge out of the higher level stuff:

((ITUserPlaylist)this).addTrack(track);

Faxwell Mingleton 2009-09-01 17:50:49

I've voted you up cos you seem pretty much right, in your reading of the problem, but I don't really understand your suggested correction. How can the type of java object which is not passed into the COM API (it merely contains the object that is) can affect the behaviour of iTunes.

l0st3d 2009-09-01 19:34:03

@l0st3d I don't have much familiarity with that library you're using (I've never used anything on top of JACOB with the iTunes SDK) so I wasn't sure what the library was actually doing when it makes those objects, or where the dispatch for the object comes from. Really, though, the hope was to try to reduce the case down to using ITUserPlaylist's addTrack method to eliminate user error and narrow it down to the API, which you obviously already accomplished. Sorry if I posted anything potentially confusing, just figured I might be able to help since I've been through these hoops before.

Faxwell Mingleton 2009-09-01 19:42:56

@lurkingfridge79 - any and all help is appreciated :)

l0st3d 2009-09-01 19:53:43

Answer 2

+1 A:

The answer for me was to contact the developer of the library I was using, getting him to release a new version of the library. If you want to do this then use at least version 0.2, which will correctly differentiate between ITPlaylist objects and ITUserPlaylist ones, which (as mentioned by lurkingfridge79 are the only types of playlist that can have tracks added to them by the COM API.

l0st3d 2009-09-01 19:28:40

Did you try doing a cast at all as I mentioned? I'm curious to see if that would work at all or if it would do funny things to the COM bridge...

Faxwell Mingleton 2009-09-01 19:30:56

no, sorry, I didn't - I'd already got the updated library before I came back to SO and saw your reply. I'm not really sure that it will work though.

l0st3d 2009-09-01 19:36:26

After replying above I'm in agreement thinking that almost certainly would fail. Glad to see there's been a library update though!

Faxwell Mingleton 2009-09-01 19:46:23

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Create a playlist in iTunes with COM and Java

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