Sybex 11 - Chapter 11-pg 480 (Modules)

[Blad Baez]

Good morning all!

I am trying to practice some of the commands showed on the examples, specifically for the jar command that describes a module.

jar -f mods/zoo.animal.feeding.jar -d

When I do this, the command-line shows (see attached image):

So, I don't understand what is the issue. I had the code from the repo, then rewrite it all over again, and still shows that message.

Does someone have an idea what could be the issue?

[Mikalai Zaikin]

I can suggest you to check what version of jar is used

Can you perhaps try

java -version
where jar

[Blad Baez]

I tried what you suggested and I have this output (see image)

Mikalai Zaikin wrote:I can suggest you to check what version of jar is used

Can you perhaps try

java -version
where jar

[Mikalai Zaikin]

Apparently, you use JAR from Java 8 install -- it's higher than Java 11 in the second command output

So, I suggest you go and edit the %PATH% environment variable (this may break some other applications that rely on your machine on Java 8 by default), OR provide a full absolute path to JAR from v.11 location for a quick check

If you plan to practice further with Java 11 on this machine, maybe updating %PATH% is a better idea...

[Campbell Ritchie]

Mikalai Zaikin wrote:. . . this may break some other applications . . .

Would it break anything? Although some API was deprecated in Java9, I don't think anything was removed, so I wouldn't anticipate any problems.

[Mikalai Zaikin]

You can't be too careful these days (c) Hagrid
I personally got Swing PLAF problem when moved to Java 11 on Windows

[Stephan van Hulst]

The problem is not the wrong Java version. The screenshot clearly shows Java 11 being used.

The problem is that the command is just wrong. It even tells you what is wrong: one of -c -t -x or -u must be specified.

Besides that, an illegal option was provided: -d.

[Mikalai Zaikin]

Before posting my answer I tried, and these jar options (-f -d) were ok (although I used Java 17 JDK)

[Stephan van Hulst]

It's my mistake, I saw that the java -version command ouput Java 11, so I assumed the same was true for the jar command.

Blad Baez, please run the following command: jar --version

[Blad Baez]

Thank you Mikalai Zaikin.

I just removed the 1.8 version from the PATH on the environment variables.
Now, the jar commands work as intended. I also can see the jar version, which is jar 11.0.16.1

Thank you again!

[Mikalai Zaikin]

Sounds good!
Have fun ;-)