I'm trying to run DMelt programs (http://jwork.org/dmelt/) program using Java9 (JDK9), and it gives me errors such as:
WARNING: An illegal reflective access operation has occurred
WARNING: Illegal reflective access by org.python.core.PySystemState (file:/dmelt/jehep/lib/jython/jython.jar) to method java.io.Console.encoding()
WARNING: Please consider reporting this to the maintainers of org.python.core.PySystemState
WARNING: Use --illegal-access=warn to enable warnings of further illegal reflective access operations
WARNING: All illegal access operations will be denied in a future release
How can I fix it? I was trying to add –illegal-access=permit to the last line of the script "dmelt.sh" (I'm using bash in Linux), but this did not solve this problem. I'm very frustrating with this. I was using this program very often, for very long time. Maybe I should never move to JDK9
The ideal way to resolve this would be to
reporting this to the maintainers of org.python.core.PySystemState
and asking them to fix such reflective access going forward.
If the default mode permits illegal reflective access, however, then
it's essential to make that known so that people aren't surprised when
this is no longer the default mode in a future release.
From one of the threads on the mailing list :
--illegal-access=permit
This will be the default mode for JDK 9. It opens every package in
every explicit module to code in all unnamed modules, i.e., code on
the class path, just as --permit-illegal-access does today.
The first illegal reflective-access operation causes a warning to be
issued, as with --permit-illegal-access, but no warnings are issued
after that point. This single warning will describe how to enable
further warnings.
--illegal-access=deny
This disables all illegal reflective-access operations except for
those enabled by other command-line options, such as --add-opens.
This will become the default mode in a future release.
Warning messages in any mode can be avoided, as before, by the judicious use of the --add-exports and --add-opens options.
Hence a current temporary solution available is to use --add-exports as the VM arguments as mentioned in the docs :
--add-exports module/package=target-module(,target-module)*
Updates module to export package to target-module, regardless of
module declaration. The target-module can be all unnamed to export to
all unnamed modules.
This would allow the target-module to access all public types in package. In case you want to access the jdk internal classes which would still be encapsulated, you would have to allow a deep reflection using the --add-opens argument as:
--add-opens module/package=target-module(,target-module)*
Updates module to open package to target-module, regardless of module
declaration.
In your case to currently access the java.io.Console, you can simply add this as a VM option -
--add-opens java.base/java.io=ALL-UNNAMED
Also, note from the same thread as linked above
When deny becomes the default mode then I expect permit to remain supported for at least one release, so that developers can continue to migrate their code. The permit, warn, and debug modes will, over time, be removed, as will the --illegal-access option itself.
So it's better to change the implementation and follow the ideal solution to it.
DMelt seems to use Jython and this warning is something that the Jython maintainers will need to address. There is an issue tracking it here:
http://bugs.jython.org/issue2582
To avoid this error, you need to redefine maven-war-plugin to a newer one. For example:
<plugins>
. . .
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.2</version>
</plugin>
</plugins>
P.S. Works for jdk-12
Jython developers do not have any practical solution for jdk9, according to this post http://bugs.jython.org/issue2582.
The previous explanation seems very long to figure out what should done. I just want jdk9 behaves exactly as jdk1.4 - 1.8, i.e be totally silent. The JVM strength in backward comparability. I'm totally OK to have additional options in JDK9, but new features cannot break applications
Real issue is a problem in the JDK. There is actually no illegal access, but the JDK method trySetAccessible is misbehaving. This will hopefully be fixed in a future JDK version.
try solve below answer link
Perhaps the fix below works for java 9 as well:
In my case the java open jdk version was 10.0.2 and got the same error (An illegal reflective access opeeration has occurred). I upgraded maven to version 3.6.0 on linux, and the problem was gone.
Since the Java update 9, the "illegal reflective access operation has occurred" warning occurs.
I added --illegal-access=permit in my eclipse.ini but it does not resolve the warning when creating a build in eclipse from Maven.
Try replacing the maven compile plugin. I have resolved this from the Maven Build and Maven Install by modify my pom.xml file in multiple projects when i did upgrade to from jdk1.8 to jdk1.12 as per the following examples:
Change version from:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>2.4</version>
<configuration>
<warSourceDirectory>WebContent</warSourceDirectory>
<webXml>WebContent\WEB-INF\web.xml</webXml>
</configuration>
</plugin>
To:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.3</version>
<configuration>
<warSourceDirectory>WebContent</warSourceDirectory>
<webXml>WebContent\WEB-INF\web.xml</webXml>
</configuration>
</plugin>
And also changed the artifactId and version From:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.5.1</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
TO:
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-war-plugin</artifactId>
<version>3.2.3</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
<encoding>UTF-8</encoding>
</configuration>
</plugin>
When i re-run Maven Build or Maven Install, the "illegal reflective access operation has occurred" is gone
