When referencing simple .jar files, Eclipse shows an error stating:
The package java.awt is accessible from more than one module: <unnamed>, java.desktop
This happens for instance when javax.awt or javax.swing is included in the .jar files.
The simplest example would be the following:
package test;
import javax.swing.JDialog;
public class Test {
public static void main(String[] args) {
new JDialog();
}
}
Adding a .jar file to the classpath with only the folder structure javax/swing (no files needed) will cause the error to appear. I'm using JDK 10/12 (neither works). Setting the compiler compliance to 1.8 makes the whole thing work again.
On another machine with Eclipse 2018-09 this works with compiler compliance set to 10.
I'm on Eclipse 2019-03, on a (for testing purposes) freshly installed Eclipse 2018-09 it works fine. Why?
Edit June/2020 (Solution)
As the answers correctly stated, this is a restriction built into Java ages ago and only recently was forced upon us. I came into contact with it while migrating a big project with dozens of dependencies to Maven. There were libraries from around the year 2000! There were 'meta libraries' which consisted of several libraries packaged together.
So there was no other way than to identify what was still needed (into the trash with the rest!), update libraries which violate the rules or find replacements for them. This took me many, many hours.
In the end it worked out and we've got a nice Maven project to work with.
This is caused by
a JAR on the Classpath that contains the package java.awt that also exists in the system library but the
JRE System Library is on the Modulepath
In the Java Platform Module System (JPMS) it is not allowed to use the same package in more than one module. If the Modulepath and the Classpath is used, everything on the Classpath is handled as the <unnamed> module (in your case the package java.awt exists in the system module java.desktop and also via the JAR on the Classpath in the module <unnamed>).
Since the JRE System Library cannot be moved from the Modulepath to the Classpath (see this answer by Stephan Herrmann for details), you only have the following options:
Set the compiler compliance to 1.8 (as you already mentioned)
Rebuilt the JAR to avoid Java system library package names inside the JAR (if reflection is used, additional code changes may be necessary):
If you have the source code, change the package names (e.g. change the package and subpackae java to java_util and javax to javax_util) and recreate the JAR
If you have only the .class files you have to decompile the .class files first
Since I'll bet lots of people will be running into this problem with modular Java, I'll help and give the real answer.
This error happens when
you have a dependency in your project
that contains code
using packages
that are also in the modules
being referenced by your project
If your project has set the source compatibility to something like Java 12, it will start enforcing the rule, that has been there all along in Java:
"Don't use packages that belong to the JDK in your own code."
Unfortunately, lots of developers and vendors have done that over the years. Can't do that anymore.
If you set your project to Java 12 source compatibility, Eclipse adds the JDK modules which include everything "java.*" and "javax.*" and even "jdk.*", "org.w3c.*". These packages may be in use by your dependencies or their transitive dependencies.
How to fix
You need to:
look at which package its complaining about
and expand the "Projects and External Dependencies" node in the Package Explorer.
Find out which dependency is using that package.
Then you can simply exclude that dependency from your project.
Or you could get the source of that dependency, if available, and rebuild the jar with changed packages. Otherwise you have to remove that dependency and find a replacement for that technology. Pain huh?
If its a transitive dependency you can often just exclude it. Here is an example of that for Gradle based projects.
GradleConfig.xml:
configurations {
all*.exclude group: 'xml-apis'
}
In my case, it was because I included a dependency (Apache Tika) in the POM.xml file.
I had to force the exclusion of the module that contained the classes with errors while imported at that dependency:
<dependency>
<groupId>org.apache.tika</groupId>
<artifactId>tika-parsers</artifactId>
<version>1.24.1</version>
<exclusions>
<exclusion>
<groupId>xml-apis</groupId>
<artifactId>xml-apis</artifactId>
</exclusion>
</exclusions>
</dependency>
It worked for me that way.
I found a simple solution to troubleshoot this in Eclipse. Hit Ctrl + Shift + T in Eclipse to open the Open Type prompt. Then type the name of the package that is causing the issue. For me, it was org.w3c.dom. Now the search results will show all the locations from where this package is being loaded. Remove every JAR from the classpath that comes in the result other than the JDK 11 library.
My project being a legacy one, I had to remove a lot of JARs from the build path. Also, my project does not use Maven. So removing the JARs was a fairly straightforward step. The steps might vary for other build tools like ANT, Maven, Gradle, etc. I have just explained the troubleshooting steps above.
See also: The package org.w3c.dom is accessible from more than one module: <unnamed>, java.xml where I answered:
Disappointingly I don't see any compiler flags to show what jar the problem is with
Even -Xlint:module doesn't seem to show up anything useful and eclipse doesn't shed any light on the issue
Instead to find where java.awt comes from I've been using this script:
mvn dependency:copy-dependencies -DincludeScope=test -DoutputDirectory=deps
for i in deps/*.jar; do if unzip -l $i| grep -q java.awt; then echo $i; fi ; done
Strictly you don't have to specify the scope test as that's the default but I've included it as you might want to use compile instead
I think my flavour of the problem might be useful.
I got this error for classes under javax.xml.stream, by old Maven projects that depend on artifacts like xml-apis, stax-api, or geronimo-stax-api.
Technically, the problem is what others have already said: those artifacts expose the javax.xml.* package without any awareness of Java modules (they were invented later), so the package is automatically assigned to the unnamed module, which conflicts with the same package being included in the JDK's most recent versions, where the package has its own module name, and therefore the same package results in two different modules, which is forbidden.
That said, the practical solution is essentially to work with Maven exclusions to remove those dependencies from your project and let it use the JDK version instead (or, of course, remove them as direct dependencies, if that's your case). Use the equivalent if you're working with another build system.
In theory, the more recent flavours of these packages offered by the JDK might be non backward-compatible, in practice, I doubt such JSR specifications changed much over the years and so far, I haven't seen any issue with their replacement.
Since this is ranks quite high on Google I'm going to drop this here in case it's helpful for someone.
I've found some interesting behaviour with Java 11 and the xmlbeans library. The xmlbeans library is a transitive dependency of Apache POI, a very popular library for working with Microsoft Office documents, it is used to handle the internal XML structures of the newer Office formats. I've tested it with Apache POI 3.9 and it works perfectly fine, despite the error shown by Eclipse. So, I guess in Java 11 this rule it's not fully enforced.
For Apache POI version 5.0.0 using Maven, in the pom.xml:
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi</artifactId>
<version>5.0.0</version>
</dependency>
<dependency>
<groupId>org.apache.poi</groupId>
<artifactId>poi-ooxml</artifactId>
<version>5.0.0</version>
<exclusions>
<exclusion>
<groupId>xml-apis</groupId>
<artifactId>xml-apis</artifactId>
</exclusion>
</exclusions>
</dependency>
Fixed: "The package javax.xml.parsers is accessible from more than one module"
I met a similar issue with the eclipse IDE while upgrading JDK from 1.8 to 11, "The package org.w3c.dom is accessible from more than one module: , java.xml". upgrading eclipse from 2019 to 2021 and setting system JDK home to 11 does not solve it. I don't think it's caused by "org.w3c.dom" existing in different jars of the classpath,dut to "Order and Export" should ordered the search sequence.
After several hours of searching and investigating, this issue is fixed by setting the Java Compiler - Compiler compliance level to 1.8(default is 11).
You can do what other people suggest which is to exclude xml-apis which worked fine with me, but if your are using and an old jaxb-api replace them with jakarta.xml.bind-api:
<dependency>
<groupId>jakarta.xml.bind</groupId>
<artifactId>jakarta.xml.bind-api</artifactId>
<version>2.3.3</version>
</dependency>
and of course upgrade your jaxb-impl to match the same api:
<dependency>
<groupId>com.sun.xml.bind</groupId>
<artifactId>jaxb-impl</artifactId>
<version>2.3.3</version>
</dependency>
Steps below helped me,
Right click Eclipse project > Properties > Java Build Path
In Libraries tab, remove all the external jar files under Modulepath and add them under Classpath (you can just select all the jars and drag them under Classpath)
Click Apply and Close
Hope it help you too.
Wow, this was a tough one!
Some helpful tips (a summary of my journey through this maze):
This started when I migrated from Java 1.8 to 11.0.11
Right out of the gate this caused problems. I needed to change the syntax for how to specify the Java version for the maven build plug in as shown below:
Before
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.7.0</version>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
After
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.8.0</version>
<configuration>
<release>11</release>
</configuration>
</plugin>
After that, everything compiled at a command prompt. However, when opening the project in Eclipse, I got a bunch of errors as shown in the next section.
Getting "<class> cannot be resolved to a type" errors
When I got errors in Eclipse and not at the command line I immediately started looking at configuration settings in Eclipse to no avail. After some googling I came to this post. The post at https://www.eclipse.org/forums/index.php/t/1110036/ was also very helpful.
Finding what resources were the problem
The answer to this post by #Anu suggesting using <shift><ctrl>T to bring up the type search window was very helpful using this I was able to see what resources were causing the problem (i.e. any resource that is also included in the JDK, in my case it was the ErrorHandler in the xml-apis jar). Type the name of one of the resources giving a "cannot be resolved to type" to see the name of the jar file, in my case the jar is xml-apis-1.4.01.jar.
All of this is shown in the screen shot below (click on the image to get a cleaner view).
Finding the Dependency that contains the offending jar
We can now use the information from https://www.eclipse.org/forums/index.php/t/1110036/ to find the dependency in our pom.xml file that contains the offending resource.
Open the pom.xml file in Eclipse and select the "Dependency Hierarchy". In the filter type the name of the jar file we found in the previous step (in my case it was xml-apis).
This will pull up the dependencies creating the problem. A screen shot of the Dependencies Hierarchy filtered for "xml-apis". From this we can see the offending dependencies in our pom.xml file are xercesImpl and xlsx-streamer.
Solving the problem
We can now add exclusions to these dependencies that will resolve the problem as shown below.
<dependency>
<groupId>com.monitorjbl</groupId>
<artifactId>xlsx-streamer</artifactId>
<version>2.1.0</version>
<exclusions>
<exclusion>
<groupId>xml-apis</groupId>
<artifactId>xml-apis</artifactId>
</exclusion>
</exclusions>
</dependency>
<dependency>
<groupId>xerces</groupId>
<artifactId>xercesImpl</artifactId>
<version>2.12.0</version>
<exclusions>
<exclusion>
<groupId>xml-apis</groupId>
<artifactId>xml-apis</artifactId>
</exclusion>
</exclusions>
</dependency>
And this fixes the current problem.
For anyone who suffer with this problem when refering to the org.w3c or javax.xml imports, be careful with this one module dependency: xml-apis it conflicts with java default xml classes.
One big project who references it is called DynamicJasper
Here's the image of my app
It seems to me the real problem here is that the JDK (in my case, JDK-19) has org.w3c.dom embedded in it, so everything else that was doing the correct thing by referencing libraries from external-lib, rather than embedding is now broken. I removed xml-apis and xerces, but it still complains about org.w3c.dom. the only place it is referenced in my project is the JDK.
Removing jar files, (xml-apis.jar and xerces_2_5_0.jar) Does not fix the issue. I cannot remove batik, project depends upon it.
I have a standard Java build, no maven. There is no decompiling/removing a valid reference that can be done with 3rd party software like batik.
Any suggestions on how to remove the embedded org.w3c.dom from JDK-19 so I can build?
I had this problem with the Stanford Core NLP package. As mentioned above adding an exclusion in the pom.xml solved the problem:
<dependency>
<groupId>edu.stanford.nlp</groupId>
<artifactId>stanford-corenlp</artifactId>
<version>4.5.2</version>
<exclusions>
<exclusion>
<groupId>xml-apis</groupId>
<artifactId>xml-apis</artifactId>
</exclusion>
</exclusions>
</dependency>
First of all, make sure your pom is actually correct by running
mvn install
if that works, and eclipse still complains look at build path and find the library it is holding onto that is not in your pom.
Sometimes I just
rm .classpath
rm -rf .settings
rm -rf project
mvn eclipse:clean eclipse:eclipse
We're using iText in one of our projects to generate PDF reports, precisely the version 4.2.1 because it is the last free version.
<dependency>
<groupId>com.lowagie</groupId>
<artifactId>itext</artifactId>
<version>4.2.1</version>
</dependency>
When I cloned the repository on an new machine this morning, I faced a lot of compiler errors, because maven redirects to version 5.5.6 and the imports are failing. On our research, we found out, that the pom-file in maven central was changed last week. From now on, it seems to be impossible to add the jar dependency like we did before.
Can anyone tell me, if there is still a way to integrate iText in version 4.2.1 via maven?
As documented here, the people who published the iText forks versions 4.x.y didn't follow the rules as explained by Apache:
I have a patched version of the foo project developed at foo.com, what groupId should I use?
When you patch / modify a third party project,
that patched version becomes your project and therefore should be
distributed under a groupId you control as any project you would have
developed, never under com.foo. See above considerations about
groupId.
They published an unofficial version of iText using a groupId that led people to believe that they were using an original version of iText, which was not the case. This error has caused much confusion and frustration.
To stop the confusion, iText Group has reclaimed the groupId so that no third party can introduce software that infringes third part rights or even malware into your code base (this is a risk you take when you allow Maven to automatically upgrade).
Your allegation that iText 4.2.1 is the last free version is incorrect. There are some serious issues with iText versions prior to iText 5, but that's another discussion and the subject of a conference talk at JavaOne 2015 entitled IANAL: What Developers Should Know About IP and Legal.
In any case, the easiest solution is for you to change the dependecy to:
<dependency>
<groupId>com.lowagie</groupId>
<artifactId>itext</artifactId>
<version>[1.02b,2.1.7]</version>
<scope>compile</scope>
</dependency>
See this answer in answer to Dependency error in jasper-reports from itext for even more background information.
First solution
You can download the jar locally and then install it locally with the following command.
mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id>
-DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging>
Use groupId, artifactId, version and packaging you like.
In this case:
mvn install:install-file -Dfile=itext.jar -DgroupId=com.lowagie
-DartifactId=itext -Dversion=4.2.1 -Dpackaging=jar
Second solution:
You can also download the jar locally and reference it with the following dependency group
<dependency>
<groupId>com.lowagie</groupId>
<artifactId>itext</artifactId>
<version>4.2.1</version>
<scope>system</scope>
<systemPath>/PATHTOJAR/itext.jar</systemPath>
</dependency>
I know this is an old thread, but I'd just cleared out my .m2 folder due to some random issues, and unfortunately then got "The artifact com.lowagie:itext:jar:4.2.1 has been relocated to com.itextpdf:itextpdf:jar:5.5.6".
Just came across this here while trying to remember how we fixed, so thought I'd post solution we had to stop it trying to upgrade.
Goto %UserProfiles%\.m2\repository\com\lowagie\itext\4.2.1\
Edit the itext-4.2.1.pom and remove the following section from the bottom and it won't bother you again and you can happily use 4.2.1 :-
<distributionManagement>
<relocation>
<groupId>com.itextpdf</groupId>
<artifactId>itextpdf</artifactId>
<version>5.5.6</version>
<message>After release 2.1.7, iText moved from the MPLicense to the AGPLicense.
The groupId changed from com.lowagie to com.itextpdf and the artifactId from itext to itextpdf.
See http://itextpdf.com/functionalitycomparison for more information.</message>
</relocation>
</distributionManagement>
I had the same problem using Gradle.
In my build.gradle file, under dependencies,
compile 'com.lowagie:itext:4.2.1'
would fetch itextpdf-5.5.6.jar
Running the command
gradle myapp:dependencies
would show a transitive dependency like this:
\--- com.lowagie:itext:4.2.1
\--- com.itextpdf:itextpdf:5.5.6
My solution was to upload a copy I had of the original itext-4.2.1.jar to our Nexus repository and give it a different version number.
I am trying to install the spring petcare application in my eclipse/tomcat7 installation, and I am getting the following error message when I try Run As..Maven Build in eclipse:
POM for joda-time:joda-time-jsptags:jar:1.0.2 is missing, no dependency information available
Here is a link to the complete stack trace. And here is a link to pom.xml. The entire code for the application can be found at this link. I have not changed anything in the application's code yet because I have not even gotten it to compile.
The jar in question seems to be in my local maven repository, so the problem may be that the app is simply not seeing it.
Can anyone help me get this to compile?
Actually looking at http://search.maven.org and the pom for that artifact is indeed missing! However the pom later version does exist.
Assuming that artifact is backward compatible I think you can fix it simply by upgrading joda-time-jsptags to 1.1.
Find and update following dependency on the pom.xml
<dependency>
<groupId>joda-time</groupId>
<artifactId>joda-time-jsptags</artifactId>
<version>1.1</version>
<scope>runtime</scope>
</dependency>
Iam trying to implement JMS using eclipse.But when I tried to save the code, it showed that javax.jms.* cannot be resolved and there are no suggestions as well recommended by it.
How can I include it and use it? when I googled I found that javax.jms.* is not a part of java API,then how can I use it in eclipse and get my program run successfully?
I would like to implement JMS with the help of activemq,what all do I need to download and include in code?
Iam a newbie to this JMS, please suggest some references or sample code that can implement JMS using activemq.
When you download the activemq archive file from Internet. Extract this archive: /apache-activemq-x.x.x
cd into this apache... directory.
You will see activemq-all-x.x.x jar file.
Include this in your build path.
This should resolve your issue.
If it is a maven project, add the following dependency to your pom.xml and it should start working as expected.
<dependency>
<groupId>javax.jms</groupId>
<artifactId>jms</artifactId>
<version>1.1</version>
</dependency>
There are actually many ways to fix this. As already stated in the comment you need the Java Enterprise Edition API. Java EE is an abstract specification so what you need is an implementation of the JMS API. Since JMS is part of the Java EE specification the easiest thing is to download a application server such as GlassFish (which is the reference implementation) or JBoss.
I assume you already got the Java compiler so you only need the SDK, not the JDK.
Java EE 6 SDK Update 4 A free integrated development kit used to
build, test, and deploy Java EE 6 applications.
http://www.oracle.com/technetwork/java/javaee/downloads/index.html
Then after you have downloaded GlassFish you will end up with a lot of files that is an implementation of the different Java EE specification API's. You will probably want to download the plugin that I linked to beneath so that you can start, deploy and do many other administration task of your server from Eclipse. I do not use Eclipse so I don't remember if you want this version of Eclipse as well.
http://marketplace.eclipse.org/node/867
At last you want to add GlassFish to your buildpath.
I found this blog post (Scroll to "Create projects in Eclipse") if you are unsure what to add, but there are several blog posts on how to add GlassFish to the build path in Eclipse so I won't list them here.
http://www.webagesolutions.com/knowledgebase/javakb/jkb005/index.html
In addition to the answers already provided, if you are using Maven you can add the following dependency (available from Maven2 Central repo):
<dependency>
<groupId>javax.jms</groupId>
<artifactId>jms</artifactId>
</dependency>
When you have downloaded activemq zip file from http://activemq.apache.org then when you extract it, head on to .jar file of activemq(This jar file is required). Now from Eclipse do as follows:
RightClick on Project and go to Properties
Java Build Path tab
Libraries tab
Add External JARs...
Get that .jar file from activemq folder
I fixed this problem by including the dependency of Activemq.
<dependency>
<groupId>org.apache.activemq</groupId>
<artifactId>activemq-all</artifactId>
<version>5.15.0</version>
</dependency>
It can be found in jboss-jms-api.jar
If you are using/Testing ActiveMQ.
Then configure your build path and add external jar activemq-all-.jar. (Path:In )
Clean and Build.
This will helped me , will do same to you as well.
Danke,
Rahul.
If you want to resolve this issue using maven, then the correct maven dependency, available in maven repository, is the following:
<dependency>
<groupId>javax.jms</groupId>
<artifactId>jms-api</artifactId>
<version>1.1-rev-1</version>
</dependency>
See post: The following artifacts could not be resolved: javax.jms:jms:jar:1.1
I'm trying to run the YouTube JSON-C Sample in eclipse. I have followed the instructions in the link and I managed to run it in the command line using mvn -q exec:java, but when I import the project to eclipse (I use eclipse indigo), it says that "The import com.google.api.client.googleapis cannot be resolved", and gives me compiler errors in every line that is related to the api. Is there some other configuration that needs to be done? Specifically adding google-api-java-client-1.5.0-beta jars to the build path?
Ok I finally solved the problem. What did the work for me was to execute mvn eclipse:eclipse on the project folder in terminal...
You need to check if you are pulling out all the dependencies in pom.xml from the repository:
<dependencies>
<dependency>
<groupId>com.google.api-client</groupId>
<artifactId>google-api-client</artifactId>
<version>1.5.0-beta</version>
</dependency>
<dependency>
<groupId>com.google.http-client</groupId>
<artifactId>google-http-client</artifactId>
<version>1.5.0-beta</version>
</dependency>
</dependencies>
Check the settings.xml file in the Maven installation directory if it is pointing to a global repository or if you have hosted your own Nexus/Sonatype repository then make sure that your settings.xml points to that and also you must have the above two jars in your repository.
Or if you just want to get the project up and running, then instead of importing as a Maven project, just import it as a normal Java project and manually add the two libraries to the project's classpath. That should at the least get you started with the project without worrying about the Maven stuff.