Package ambiguity in java 9 modules.

[viral wolf]

I'm trying to convert my java project to modules(JPMS), One package is exist in two of my jars so i can't make build of it, How to resolve this issue, (I cant work on refactoring those jars)

[summer lava]

<@&987246452180930620> please have a look, thanks.

[thin bear]

The Java module system does not allow for split packages

your options are

1. Make a third jar with the package
2. Rename the package in one or both jars
3. Combine the jars

I cant work on refactoring those jars
Why not?

you are gonna have to change some stuff to make it work no matter what

[viral wolf]

Make a third jar with the package is that easy for long run ? Is there any tools does that unification automatically?

Why not? There were several teams working on that dependencies(jar), so making them to work for us is kinda painful job, as they are not in process to support modules for now.

[thin bear]

if you are thinking of scripting it...eh? i wouldn't. You can make it work in the long run in a few ways

i.e. by making an aggregator module

but the easiest thing is going to be to start putting dependencies on the module path and leave those + your app on the class path until you can resolve it

[viral wolf]

Cant get it ethan, Could u please explain it clearly

I use intellij, and i have place my jars under libraries then enabled in Modules > Dependencies.

[thin bear]

okay so lets say your app has three dependencies

apple.jar, banana.jar, and carrot.jar

if you were in the situation where all three didn't have split packages, you could make everything a module

and you could do this, to start, by just putting everything on the module path

java --module-path libs/apple.jar;libs/banana.jar;libs/carrot.jar ...

without module descriptors, apple, banana, and carrot would be "automatic modules"

meaning their module name would come from the jar name

but you can still modularize your app with that

module app {
    requires apple;
    requires banana;
    requires carrot;
}

so you would compile app.jar and run with it on the module path too

java --module-path libs/apple.jar;libs/banana.jar;libs/carrot.jar;libs/app.jar -m app/app.Main

and then you would go in to apple, banana, and carrot

and add explicit module descriptors as you are able

module org.apple {
    exports apple;
}

then once everything has an explicit module info and you are running from the module path you've done it

but your problem is that your equivalent of apple and banana export the same package

this is not allowed on the module path

but it is allowed on the class path

so you can still put carrot on the module path

java --module-path libs/carrot.jar

but apple and banana need to live on the class path until you fix the split package

java --module-path libs/carrot.jar --class-path libs/apple.jar;libs/banana.jar

which means that your app can't get a module info

and needs to live on the class path as well

to manually resolve this you can crush apple and banana in to one jar yourself

applebanana.jar

and then require it from your app module

module app {
    requires applebanana;
    requires carrot;
}

and once apple and banana figure their shit out and you want to use them directly, you can make your own module info

module applebanana {
    requires transitive apple;
    requires transitive banana;
}

and make an "aggregator module"

assuming you wanted to keep code that requires the applebanana module you just made working as-is

[viral wolf]

Once they fixed things, they can be used as modules right ? So why we cant use them like a module , cause because that needs some effort ?

[thin bear]

that wasn't english

you can't use them as modules because there are split packages between the jars

[viral wolf]

Wdym by their figure out things, I thought they were resolving the split packages

[thin bear]

yes

that is what i am referring to

[viral wolf]

If they've resolved things means, Then we can directly require them on our module right ?

[thin bear]

yes

they might be automatic modules

but you'd be able to require them in your module

and until they do, you either need to make your own special applebanana.jar or you cannot have a module-info for your app

but you could put some of your dependencies on the module path

as always, I can give better advice the more specific info i have

but im also curious what situation you are in that you are able to just download the jars to a folder

and aren't using maven/gradle + an internal company repo

[viral wolf]

No we dont use maven/grade

We use tomcat with war

[thin bear]

hmm

well if tomcat is loading your app, there is a decent chance you might not be able to put anything on the module path

but idk really

yeah...digging in to it a lil

Tomcat opens wars on the classpath

or at least it did as of this stack overflow post https://stackoverflow.com/questions/46618118/web-inf-lib-directory-vs-java-9-modules

so your module-infos won't take effect

and none of your deps would go on the module path

[viral wolf]

For now our need for module is to class usage restriction so even though no support for modular deployment, We can build the modular jars right ? So we can restrict the developers from not allowed classes right ?

[thin bear]

err

🤷‍♂️

ask me again in the morning

(its 2am rn)

there certainly isn't a downside to having module-infos

[viral wolf]

So not using in deployment in tomcat is not a problem right ?

[viral wolf]

It's 11:40 AM in india :ew: xD, Good Night Bro 🌃

[honest crest]

For a high level view: https://www.baeldung.com/java-modularity section 4

But I recommend checking out The Java module system or Java 9 modularity.

This tool can also help you get going: https://github.com/moditect/moditect

[summer lava]

Closed the thread.

[summer lava]

@viral wolf

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