java.lang.ref.SoftReference missing?

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Nathan Baulch - 09 Mar 2006 00:43 GMT

I'm trying to compile a Java project in Visual Studio however it would seem
that J# doesn't have an implementation of the java.lang.ref.SoftReference
class (which I imagine would be a simple wrapper over the top of a
System.WeakReference).

I'm trying to keep the project as close as possible to pure Java (ie, only
reference vjslib.dll and not mscorlib.dll) however it looks like I'll have
to contaminate it by migrating the SoftReferences to WeakReferences.

Nathan

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Bruno Jouhier - 11 Mar 2006 15:32 GMT

SoftReferences and WeakReferences have different semantics:

Objects referenced through weak references go away as soon as you don't have
any strong references to them (at the next GC pass).
Objects referenced through soft references go away when the memory starts to
fill up, if they don't have strong references pointing to them. So, they
don't go away at the next GC pass if the memory pressure is low.

So, soft references are much more practical than weak reference for caching,
and you will need to do some extra work (keeping extra strong references and
breaking them when memory pressure gets high) if you want to reproduce the
soft reference behavior with weak references.

2 reasons why J# does not have soft references:

* it is based on JDK 1.1.4, which did not have soft references.
* the .NET framework (even 2.0) only provides weak references.

Bruno

> I'm trying to compile a Java project in Visual Studio however it would
> seem that J# doesn't have an implementation of the
[quoted text clipped - 6 lines]
>
> Nathan

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java.lang.ref.SoftReference missing?

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