Does Java 1.5 have circular linkedlist implementation?

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Sharp - 12 Mar 2005 05:50 GMT

Hi
Does Java 1.5 have circular linkedlist implementation?
if not, where can I find a 3rd party API that has it?

Cheers
Sharp

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Tony Morris - 12 Mar 2005 06:32 GMT

> Hi
> Does Java 1.5 have circular linkedlist implementation?
> if not, where can I find a 3rd party API that has it?
>
> Cheers
> Sharp

No.
Google could turn one up, but I see no reason to spend the 5 or 10 minutes
writing it yourself instead (perhaps a tad more if you write tests and
javadoc, like you should).
Note that a circular linked list cannot be implemented successfully (without
design flaws) by implementing the java.util.List interface -I've seen many
of my university students try.

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Tony Morris
http://xdweb.net/~dibblego/

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Kevin McMurtrie - 12 Mar 2005 07:58 GMT

> > Hi
> > Does Java 1.5 have circular linkedlist implementation?
[quoted text clipped - 10 lines]
> design flaws) by implementing the java.util.List interface -I've seen many
> of my university students try.

I don't see why it can't implement List if given a reference point and
direction. It couldn't cleanly support concurrent modification through
itself and an Iterator but that's a common limitation.

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Thomas G. Marshall - 13 Mar 2005 07:12 GMT

Kevin McMurtrie coughed up:

>>> Hi
>>> Does Java 1.5 have circular linkedlist implementation?
[quoted text clipped - 13 lines]
> I don't see why it can't implement List if given a reference point and
> direction.

I've seen this discussion a few times. You can specify a reference point,
but that reference point is hard to pin down in a generic sense. What
constitutes the head, or better put, "the way in" to a circular linked list
is often goofy.

> It couldn't cleanly support concurrent modification
> through itself and an Iterator but that's a common limitation.

You could specify a ListIterator, which is what you get from List
implementors anyway. And a ListIterator has the add() and remove() methods
needed for such concurrent things. Once you've chosen that arbitrary head
and tail in the circle, the ListIterator could be designed in a similar way
it is for ArrayList.

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Does Java 1.5 have circular linkedlist implementation?

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