CODEWITHSUNDEEP
javajava-9jlink
user3532588
user3532588

Reputation: 21

JDK 9 jlink is giving Error: --output must be specified

I am new to JDK 9 and trying to use jlink to generate a runtime for a simple app.

I have the following module descriptors

module reader{

        // no "requires" entries implies no dependency on other modules

        // other modules can access org.reader package
        // all other packages are implicitly unavailable

        exports org.reader;
    }

and 

module decoder {

    // depends on reader module
    requires reader;

    // exposes com.decoder package to modules which require decoder module
    // all other packages in decoder module are implicitly unavailable to other modules
    exports com.decoder;
}

I defined a couple of simple classes called Reader.java and Decoder.java, and am able compile and run them using the following steps.

(1) Download and unzip JDK and JRE 9.0.4 to a test directory

(2) Create the following directory structure inside the test directory. 

/moduleExamples/readerDecoderExample/src/main/java
/moduleExamples/readerDecoderExample/src/main/java/reader
/moduleExamples/readerDecoderExample/src/main/java/decoder

(3) Add reader module-info.java, org/reader/Reader.java to reader directory. Add decoder module-info.java, com/decoder/Decoder .java to decoder directory.

(4) Navigate to test/moduleExamples/readerDecoderExample directory, run the following commands

export JAVA_HOME=test/jdk9.0.4 mkdir mods export MODULE_PATH=test/moduleExamples/readerDecoderExample/mods

(5) Compile reader and decoder modules

${JAVA_HOME}/bin/javac -d mods --module-source-path src/main/java/ $(find src/main/java -name "*.java")

(6) Run the Decoder class

${JAVA_HOME}/bin/java --module-path mods -m decoder/com.decoder.Decoder input.txt

(7) mkdir mlibs

(8) Package modules into jars using the following commands.

    ${JAVA_HOME}/bin/jar --create --file mlibs/[email protected] --module-version=1.0 -C mods/reader .

${JAVA_HOME}/bin/jar --create --file mlibs/decoder.jar --main-class=com.decoder.Decoder -C mods/decoder .

(9) At the end of step (8), I have a mlibs dir as shown below

readerDecoderExample/mlibs/decoder.jar
readerDecoderExample/mlibs/[email protected]

(10) When I try to build a JRE with the following command

${JAVA_HOME}/bin/jlink --module-path ${JAVA_HOME}/jmods;mlibs/[email protected] --add-modules [email protected] --output out

I get the following error.

Error: --output must be specified

Can somebody please tell me what I am doing wrong?

Thank you in advance!

Upvotes: 2

Views: 1349

Answers (2)

Dmitry V.
Dmitry V.

Reputation: 51

Flag --output is an option and should be placed before --module-path flag.

Usage: jlink <options> --module-path <modulepath> --add-modules <module>[,<module>...]

In case of several module-path's - ':' delimiter was correct for me (Ubuntu).

Upvotes: 0

ruppyrup
ruppyrup

Reputation: 16

I came across the same problem on gitbash when I was doing a demo at work. I had tried it previously on a mac and the ${JAVA_HOME}/jmods;mlibs/[email protected] works fine, just changing : to ; when moving to PC.

The error seemed to be around the jmods so I just removed it and it worked fine - not sure how or why, this approach doesn't work on the mac.

The following should work:

${JAVA_HOME}/bin/jlink --module-path mlibs/[email protected] --add-modules [email protected] --output out

Upvotes: 0

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