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NNTP-Posting-Date: Sat, 07 May 2011 08:40:57 -0500
Date: Sat, 07 May 2011 06:40:55 -0700
From: Patricia Shanahan <pats@acm.org>
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Subject: Re: Concurrent bidirectional one-to-many map?
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On 5/7/2011 2:43 AM, Sebastian wrote:
...
> To give an example, I'm trying to solve a problem like this:
> Associate tasks with workspaces, where a workspace may hold many
> tasks,but a task may be associate with at most one workspace.
...

I'd deal with that sort of problem by having a custom data structure
that uses java.util structures in its implementation.

For example, class TaskMapping could have a Map<Task,Workspace> that
maps a task to its workspace, and a Map<Workspace,Set<Task>> that maps a
workspace to the set of tasks it currently holds.

TaskMapping would have methods such as:

add(Task t, Workspace w)
remove(Task t, Workspace w)
Iterable<Task> getTasks(Workspace w)

To the rest of the program it looks like a unified data structure, but
each operation uses a data structure that is well suited to the types of
access it does.

Patricia