creating module-info for automatic modules with jdeps in java 9

Question

I have 3 jar of jackson library

1. jackson-core-2.8.10.jar
2. jackson-annotations-2.8.0.jar
3. jackson-databind-2.8.10.jar

I created m

Answer 1

The accepted answer describes to create Java 9 module info for libraries that do not provide it (they are treated as automatic modules).

Jackson, starting with version 2.10.0, actually provides Java 9 module info.

Answer 2

The short answer is that, yes, you'll have to convert the libraries to explicit modules.

The jlink tool is intended to provide a trimmed binary image that has only the required modules. The issue is that automatic modules have access to the classpath (aka the unnamed module) which can read all JDK modules. So nothing would be trimmed.

This thread states this as well, with a link to a YouTube video.

This example converts commons-lang3-3.5.jar to an explict module for a jlink demo.

Edit: to be more specific, here is an example script that converts, in order, jackson-core, jackson-annotations, and jackson-databind legacy jars to modular jars.

The idea is:

• run jdeps --generate-module-info on the legacy jar
• unzip the legacy jar into a folder, add module-info.java from above, re-compile, and re-zip

The trick is that modular jars with dependencies will require those dependencies as command-line parameters. For example, here is jackson-databind (abstracted somewhat):

# here, jackson-core and jackson-annotations have been built
# jackson-databind 

jdeps --module-path $ROOT_DIR/modules \
--add-modules jackson.annotations,jackson.core \
--generate-module-info work $JACKSON_DATABIND_JAR

javac --module-path $ROOT_DIR/modules \
--add-modules jackson.annotations,jackson.core \
-d $ROOT_DIR/classes module-info.java