List modules in jar file

Question

I've created what I'm pretty sure is a modular jar file. But if possible, I'd like to double check. Given a jar file, is there a way to determine what modules the compiler would find within it?

score 43 · Accepted Answer · answered Oct 07 '17 at 07:52

43

The alternative is to use the jar --describe-module (-d for short), e.g.:

jar --file=myjar.jar --describe-module

answered Oct 07 '17 at 07:52

Alan Bateman

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Naman · Answer 2 · 2021-01-02T13:28:37.237

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You can list the modules within the jar using the following java tool command:-

java -p yourModular.jar --list-modules

Edit: You shall preferably make use of the jar command lin as suggested in @Alan's answer.

edited Jan 02 '21 at 13:28

answered Oct 07 '17 at 05:37

Naman

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I recommend to [use `jar --describe-module`](https://stackoverflow.com/a/46617956/2525313) instead - it's much more precise and contains more relevant information. – Nicolai Parlog Oct 07 '17 at 14:11
This way is handy for checking which modules are built into the runtime image (say as built using jlink/jpackage) with `java --list-modules`. – DuncG May 21 '23 at 10:39

score -4 · Answer 3 · answered Oct 07 '17 at 04:11

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To extract the contents of a JAR file to see what’s inside, change the extension of the JAR from .jar to .zip. Then you can extract the files with whatever zip extraction tool you choose.

answered Oct 07 '17 at 04:11

Steampunkery

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I know how to extract the jar. I was wondering if there was an easier way to determine what modules it contains than poring over the source files. – PopKernel Oct 07 '17 at 04:13
Modules? Do you mean external libraries? – Steampunkery Oct 07 '17 at 04:14
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No, modules as in Java 9 modules, aka project Jigsaw… – PopKernel Oct 07 '17 at 04:15
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I’m sorry, I’ve never worked in Java 9. I misunderstood the question. I don’t know if any way to do what you are asking. – Steampunkery Oct 07 '17 at 04:20

List modules in jar file

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