🚀 go-pugleaf

John Steel wrote:
>     public Collection getValues() {
>         return gameListTreeMap.values();
>     }
> ...
> }
> 
> As you can see getValues() returns a Collection, so I can't see what the 
> warning is trying to tell me.

gameListTreeMap is a TreeMap<String, GameRec>, so the values method 
returns Collection<GameRec>.  Since your getValues method returns a 
plain Collection without any generic type parameters, you've lost the 
restriction to GameRec, which is an unchecked conversion from 
Collection<GameRec> to Collection.  There are a few ways you can get rid 
of the problem.

1. Change your getValues method's return type to Collection<GameRec>. 
This is probably the most type safe solution, but depending on how big 
your API is, it might just propagate the problem up the tree.  Now 
anyone that calls your getValues method expecting a Collection is going 
to get a similar warning.  In other words:

     Collection foo = gameListManager.getValues(); // warning!

2. Add a SuppressWarnings annotation to the getValues method.  This 
basically tells the compiler, "Shut up, I know what I'm doing."  It 
works, and you probably do know what you're doing, but my preference is 
to only do that when I have no other choice (ex. the warning comes from 
interacting with some 3rd party API that I can't change).

     @SuppressWarnings("unchecked")
     public Collection getValues() {
         return gameListTreeMap.values();
     }

-- 
Gillmer J. Derge [TeamB]

"Gillmer J. Derge [TeamB]" <spam@gillmerderge.com> wrote in message 
news:4684fd6d@newsgroups.borland.com...

>> As you can see getValues() returns a Collection, so I can't see what the 
>> warning is trying to tell me.
>
> Collection<GameRec> to Collection.  There are a few ways you can get rid 
> of the problem.
>
> 1. Change your getValues method's return type to Collection<GameRec>. This 
> is probably the most type safe solution, but depending on how big your API 
> is, it might just propagate the problem up the tree.  Now anyone that 
> calls your getValues method expecting a Collection is going to get a 
> similar warning.  In other words:
>
>     Collection foo = gameListManager.getValues(); // warning!

Thanks very much for your help, this is very kind of you.
I am in control of all the source, and the api is pretty much limited to 
these 2 classes (at present!).
As expected, when I changed the GameListManagers getValues() to read

    public Collection<GameRec> getValues() {
        return gameListTreeMap.values();
    }

I found it compiled fine but then the original calling line now gives these 
2 errors:
"GameListRenderer.java": cannot find symbol; symbol  : constructor 
ArrayList(java.util.Collection<GameRec>), location: class 
java.util.ArrayList<java.util.Collection> at line 94, column 40
"GameListRenderer.java": internal error; cannot instantiate 
java.util.ArrayList.<init> at java.util.ArrayList<java.util.Collection> to 
() at line 94, column 40

I'm trying to think this through by describing it in English - I think I'm 
asking for an ArrayList of GameRecs, but we know games.getValues() now 
returns the type safe Collection so its almost as if the syntax end up like 
ArrayList<Collection<GameRec>> gameList =...  , but that wouldn't compile at 
all

(the original caller is     ArrayList<Collection> gameList = new ArrayList 
<Collection> (games.getValues()); ).

I too would like a clean build without "hacks".  There are a few others of 
this ilk relating to Comparators, so I'd like to fix those having understood 
this one.

John Steel wrote:
> (the original caller is     ArrayList<Collection> gameList = new ArrayList 
> <Collection> (games.getValues()); ).

Your new ArrayList isn't going to be a list of Collection's.  It's a 
list of GameRec's, containing the same GameRec's that are in the 
games.getValues() collection.

ArrayList<GameRec> gameList = new ArrayList<GameRec>(games.getValues());

-- 
Gillmer J. Derge [TeamB]

"Gillmer J. Derge [TeamB]" <spam@gillmerderge.com> wrote in message 
news:4685a1e7@newsgroups.borland.com...
> John Steel wrote:
>> (the original caller is     ArrayList<Collection> gameList = new 
>> ArrayList <Collection> (games.getValues()); ).
>
> Your new ArrayList isn't going to be a list of Collection's.  It's a list 
> of GameRec's, containing the same GameRec's that are in the 
> games.getValues() collection.
>
> ArrayList<GameRec> gameList = new ArrayList<GameRec>(games.getValues());
>

That did it - thanks. I even fixed the Comparater one after your help too - 
thanks again.

-- John
www.phonewebcam.com