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by didibus 3189 days ago
I'm still not sure of the practical benefits? Seems to be purely for IOT and nothing else. Am I correct?

Edit: To add to my question, jar hell was solved by tooling which generates your classpath for you. So it hasn't been an issue for me in years. And they refused to add versioning, so you still need to use those tools. Strong encapsulation just means they disabled reflection access to non public members, which I consider a regression on functionality. Either way, not a particularly useful feature to me, in fact it breaks some of my code. So I'm left with being able to have small JVMs which don't bundle the full standard lib, which seems to be mostly of use for memory constrained environments like IOT. But I'm actually hopeful there's some bigger practical benefits I'm not thinking of, so I'd love to hear from people who know more about jigsaw.
1 comments
pjmlp 3189 days ago
Encapsulation is another one.

Before Java 9, the only way to hide private APIs would be to have everything in the same JAR.

If a library is splinted across multiple JARs, then private APIs only to be used internally by library become exposed to everyone, and there will always exist someone making use of them even if explicitly marked as internal.

This is nothing new to Java, other languages e.g. Ada, Delphi, .NET and even Go have this kind of visibility concept.

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alkonaut 3189 days ago
.NET does have the module level directive "InternalsVisibleTo" that declares another assembly as a friend assembly that can use internal API's from the first assembly. So if you have e.g MyLib.Core and then two impls on top say MyLib.Windows and MyLib.OSX, where everyone would only use one of the impl libs but always the core lib (which is why it was split - then you could make internal API in the core lib visible ONLY to the Windows/OSX libs by using InternalsVisibleTo, and users of the library could not see that internal API.
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pjmlp 3189 days ago
Yep, that is what I meant by mentioning .NET in "This is nothing new to Java, other languages e.g. Ada, Delphi, .NET and even Go have this kind of visibility concept."
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alkonaut 3189 days ago
Right. Thought you meant "the file/assembly is the module, no way around it" was the concept.
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didibus 3188 days ago
I see, why would you split a library accross many Jars though? What's the advantages? Isn't it again IOT, so that if you only use part of a jar, you don't need to have the full thing loaded?
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