Generics Q: array of lists of arrays

[kjkrum]

SSSCE - there are two questions in the comments.

import java.util.LinkedList;
import java.util.List;

public class Foo {
	
	public static void main(String[] args) {
		
		// i want to create an array of lists of arrays.  this seems like the
		// right syntax, but gives an error: "Cannot create a generic array of
		// LinkedList<Foo[]>".  what is the correct syntax?
		// List<Foo[]>[] arrayOfLists = new LinkedList<Foo[]>[10];

		// this works, but complains about type safety. can I do anything
		// about this warning other than @SuppressWarnings("unchecked")?
		List<Foo[]>[] arrayOfLists = new LinkedList[1];
		
		// the declaration is actually already typesafe, because this line
		// produces a type mismatch error:
		// arrayOfLists[0] = new LinkedList<String>();
		
		// this works
		arrayOfLists[0] = new LinkedList<Foo[]>();
	}

}

[kjkrum]

Anyone? Anyone? Bueller?

[Fubarable]

Look up type erasure as I think that this is causing your problem. It's a basic limitation of Java generics. :(

This may help clarify: http://www.angelikalanger.com/Generi...rs.html#FAQ202

You may be better off creating a List of Lists:

        List<List<Foo>> listOfLists = new LinkedList<List<Foo>>();
        listOfLists.add(new ArrayList<Foo>());

[kjkrum]

Yeah... or for my particular purpose, a Map<Integer, List<Foo>>.

Thanks for that link.

[Fubarable]

Yep, that would work too. You're welcome and good luck!

I just wish that generics weren't added as an after-thought.