List the modules resolved during the application startup

Question

How can one get to know of the list of modules that have been resolved while the application has been started so as to figure out what all service providers are accessible from the root module.

Answer 1

Module Resolution

The module resolution is a two-step process.

• The first step recursively enumerates the 'requires' directives of a set of root modules.
• If all the enumerated modules are observable, then the second step computes their readability graph. The readability graph embodies how modules depend on each other, which in turn controls access across module boundaries.

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One can make use of the debugging flag as mentioned in the java tool documentation by means of a VM argument :

--show-module-resolution

Shows module resolution output during startup.

For example, the option would list out :

• root module
• all the modules required and resolved by the root module
• further bindings used by the above-required modules and
• successive modules resolved during startup

On running the following command:

Jigsaw git:(master) ✗ ../jdk-9.0.1.jdk/Contents/Home/bin/java 
                       --show-module-resolution 
                       -p ../out/production/100DaysOfJava9 
                       -m HundredDaysOfJavaNine/com.stackoverflow.nullpointer.Challenge1

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It results in the following:-

root HundredDaysOfJavaNine file:///.../out/production/100DaysOfJava9/

HundredDaysOfJavaNine requires jdk.incubator.httpclient jrt:/jdk.incubator.httpclient

java.base binds jdk.localedata jrt:/jdk.localedata
java.base binds java.security.jgss jrt:/java.security.jgss
java.base binds java.logging jrt:/java.logging
java.base binds jdk.javadoc jrt:/jdk.javadoc
java.base binds jdk.jartool jrt:/jdk.jartool
java.base binds jdk.jlink jrt:/jdk.jlink
java.base binds jdk.compiler jrt:/jdk.compiler
java.base binds jdk.jdeps jrt:/jdk.jdeps
java.base binds java.desktop jrt:/java.desktop
java.base binds jdk.zipfs jrt:/jdk.zipfs
...