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I am currently looking at consolidating to a single collections library in a project I'm involved in, and though I have little experience with it, I really like the look of Eclipse Collections.

One concrete use case we have is that we use a Map implementation with soft value references in several places as a simple cache. We currently use Apache Commons Collections' ReferenceMap for this purpose, for example:

private final Map<Integer, Long[]> cache = new ReferenceMap<>();

Of course this can be replaced by a standard Java HashMap where the value is an SoftReference implementation, but I was hoping Eclipse Collections had a similar "convenience" collection type or factory/builder for this purpose. Is there such a thing? Or perhaps more broadly formulated: how would I set up a Map with soft value references using Eclipse Collections and a minimum amount of boilerplate?

Jeen Broekstra
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Eclipse Collections does not currently have a WeakValueHashMap or SoftValueHashMap. I also can't think off hand of a way of setting one up with minimal boiler plate without implementing them. If you want to use the Eclipse Collections MutableMap API instead of Map, you can adapt the ReferenceMap above.

private final MutableMap<Integer, Long[]> cache = Maps.adapt(new ReferenceMap<>());

This won't help you get rid of the Apache Commons dependency, but gets you a step closer to a consistent API usage.

If you are interested in contributing to Eclipse Collections, there is certainly room for WeakValueHashMap and SoftValueHashMap implementations.

Donald Raab
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