I'm trying to add Stanford CoreNLP 3.9.2 as dependency to my Eclipse/Maven project:
<dependency>
<groupId>edu.stanford.nlp</groupId>
<artifactId>stanford-corenlp</artifactId>
<version>3.9.2</version>
</dependency>
Next to my POM.xml file I see a little red x icon. When I open POM.xml there is no additional information regarding the error.
When I click on Java -> Properties -> Java Build Path -> Maven Dependencies I see that the Jars that were expected to be added to Maven via this dependency are missing. This is odd because I regularly add dependencies this way without any error.
Apparently, something is preventing Maven from downloading the dependencies. What could it be?
Update:
I changed POM file to version 3.5.2 (instead of 3.9.2) and now all errors are gone.
If anyone can explain WHY this solved my problem (and how to make things work with version 3.9.2) I will accept it as the answer.
Update:
When I go to my Maven repository I see that most of the required Jars have been downloaded by Maven. For example, Maven repository will contain the folders: \\maven\.m2\repository\edu\stanford\nlp\stanford-corenlp\3.9.2 However the folder will not contain the Jar: stanford-corenlp-3.9.2 - but it will contain every other Jar such as stanford-corenlp-3.9.2-models and stanford-corenlp-3.9.2-sources etc.
This makes the whole situation even more confusing. If Maven is downloading the Jars why is it skipping just one Jar? I looked in several other folders (dependencies of corenlp) and I see similar phenomenon - it's always the main Jar of that folder that is missing.
What's worse, when I download and add the missing Jars manually to Maven folder, the (missing) text next to Jar goes away but there's still a little red x icon next to POM file. I have no idea what is going on.
Any insights?
Thanks!
I have no idea why this fixed the problem but in my POM file I had an entry:
<dependency>
<groupId>org.eclipse.platform</groupId>
<artifactId>org.eclipse.debug.core</artifactId>
<version>3.13.0</version>
</dependency>
I update this dependency to:
<dependency>
<groupId>org.eclipse.platform</groupId>
<artifactId>org.eclipse.debug.core</artifactId>
<version>3.14.0</version>
</dependency>
Now all errors have disappeared.
Here is the situation :
I want to use a locally installed jar in a springboot project. I included the dependency to this artifact in my pom.xml :
<dependency>
<groupId>org.mycie.myjar</groupId>
<artifactId>myjar</artifactId>
<version>1.0-SNAPSHOT</version>
</dependency>
This jar uses the artifact snakeyaml with version 1.16
But in my main project, Springboot uses snakeyaml version 1.23
The concurrency seems to cause some issues when running the application.
Do you have any idea on the good practices to tackle this issue?
Maven will only let one of the jars into the resulting application. You can find out by calling mvn dependency:list which jar Maven chose.
The resulting problem cannot be really solved by Maven. Instead, you need to figure out which version of snakeyaml works for all scenarios. Since one of the jars belongs to you, it is probably best to just update the dependency of myjar to avoid this problem.
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
I'm trying to convert a "classic" JAVA EE project, using IBM websphere 8.0.0.5, into a maven multi module project and facing issues with the IBM dependecies.
We use IBM classes from the following packages:
com.ibm.websphere.asynchbeans
com.ibm.websphere.scheduler
com.ibm.websphere.ce.cm
com.ibm.ws.asynchbeans
com.ibm.ws.util.ThreadPool
To get my local project to be compiled I downloaded the was.installer-8.0.0.pm from IBM and installed it to my maven using
mvn install -f "was.installer-8.0.0.pom" -D serverInstallationFolder="C:\Program Files (x86)\IBM\WebSphere\AppServer"
This step was successfull according to command line output.
I then added the following dependencies to my project as described from IBM:
In parent:
<dependency>
<groupId>com.ibm.tools.target</groupId>
<artifactId>was</artifactId>
<version>8.0.0</version>
<type>pom</type>
<scope>provided</scope>
</dependency>
In module:
<dependency>
<groupId>com.ibm.tools.target</groupId>
<artifactId>was</artifactId>
</dependency>
But I still can't compile my project as the IBM packages are not found.
Can anyone help me to find and correct a mistake I made?
Edit
After following BevynQ tip from the comments I copied the "was_public.jar" to "was_public-8.0.0.jar" (described at IBM here) and added it to my repository:
mvn install:install-file -Dfile="C:\Program Files (x86)\IBM\WebSphere\AppServer\dev\was_public-8.0.0.jar" -DpomFile="C:\Program Files (x86)\IBM\WebSphere\AppServer\dev\was_public-8.0.0.pom"
I then changed the dependencies to:
<dependency>
<groupId>com.ibm.websphere.appserver</groupId>
<artifactId>was_public</artifactId>
<version>8.0.0</version>
<scope>provided</scope>
</dependency>
<dependency>
<groupId>com.ibm.websphere.appserver</groupId>
<artifactId>was</artifactId>
</dependency>
This helped to get the compiling errors for the imports to com.ibm.websphere done.
What I now have still open is the packages com.ibm.ws.* package. Anyone have an idea?
Edit 2
I added the following dependency and then I was rid of the com.ibm.ws.* import errors.
<dependency>
<groupId>com.ibm.websphere.ws</groupId>
<artifactId>com.ibm.ws.runtime</artifactId>
<version>1.0.0</version>
</dependency>
But it still does not compile as now indirectly references can not be found (in my case commonj.work.WorkManager). It seems I need to add further .jars for every single thing. Isn't there an easier way to provide all websphere jars at once as descirbe in the above linked tutorial with the com.ibm.toolsdependency (which do not work)?
In general, com.ibm.websphere are public API for use by applications (this is true of the packages you listed above) which is consistent with these being in was_public.jar
However, com.ibm.ws package is generally product internals. May I ask what interface methods you are using from the com.ibm.ws.asynchbeans package? Maybe there is a public API alternative.
Regarding commonj.work, the only place I can find this in the WebSphere Application Server product image is WAS/plugins/com.ibm.ws.prereq.commonj-twm.jar so it looks like you will need to use that to compile against.
Here's the solution so I solved my dependency problems:
I configured the company repository manager (nexus) as a mirror. In this nexus all ibm packages are present. As you can think that solved the main problem.
I then added the following dependencies according to common maven style:
Dependencies in pom.xml (version numbers extracted to properties):
<dependency>
<groupId>com.ibm.websphere.ws</groupId>
<artifactId>com.ibm.ws.runtime</artifactId>
<version>${ibm.ws.runtime.version}</version>
</dependency>
<dependency>
<groupId>com.ibm.ws.prereq</groupId>
<artifactId>commonj-twm</artifactId>
<version>${ibm.ws.prereq.commonj-twm.version}</version>
</dependency>
Sorry I can't provide a "nice" solution that's useable by all people but the answer from njr and the comment from BevynQ helped at lot to get clearer with the problem and helped to solve the problem in a "more manual" way by copying the needed jars by hand.
I was facing this issue as I tried to build a project using Maven version 3.3.9, running on Java version 1.8.0_101, as depicted in the screenshot:
This is how I resolved it: Step 1. Download the commonj.jar from here.
Step 2. Determine which JDK your Maven is using by typing mvn -version in the command prompt.
Step 3. Go to that directory and place the commonj.jar file there in the jre/lib/ext directory, as shown below. Now your project should build in maven without any issues.
I am new to Struts2.
Whenever I include the Struts2 dependency, why do I have to do like this?
<dependency>
<groupId>org.apache.struts</groupId>
<artifactId>struts2-core</artifactId>
<version>${struts.version}</version>
<exclusions>
<exclusion>
<artifactId>tools</artifactId>
<groupId>com.sun</groupId>
</exclusion>
</exclusions>
</dependency>
If I don't do this, Eclipse Juno gives me error at this point.
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
http://maven.apache.org/maven-v4_0_0.xsd
With this error:
Missing artifact com.sun:tools:jar:1.5.0
Is this the way to do it or is there a better way?
I noticed that this problem happens from version 2.1.6 and higher.
The artifact com.sun:tools:jar:1.5.0 is a jar from the JDK (not the JRE). This jar is not available in any maven repository but is located in <JDK_HOME>/lib. That's why you get this error.
When you specify an exclusion, maven won't try to find the jar (and so it won't fail).
Struts2 requires this dependency at compile time (not at runtime).
So setting an exclusion is the correct way of getting rid of this problem. Since maven need a JDK to run: the tools.jar will be available anyway when compiling the project.
You should not need to do this.
That you do indicates there's an issue in your Eclipse, Eclipse project, and/or Eclipse Maven plugin configuration. By way of comparison, I have S2 projects for essentially every version, and in no pom do I need to exclude the Java tools jar, and never have.
PROBLEM EXPLAINED
Actually, what happens is that struts2 relies on a system dependency, namely tools.jar. This dependency is found by resolving this path: ${java.home}/../lib/tools.jar.
If you compile your project with maven, maven will be clever enough to replace ${java.home} with the right JDK location.
For some reason, if you try to compile your mavenized project with eclipse (ie with m2e help generally), ${java.home} is resolved against the -vm eclipse command line parameter.
SOLUTION
If you want to solve this issue, DO NOT exclude the tools.jar. Instead force your eclipse to run with your favorite JDK in either of the following ways (since I don't know your OS, I'll give examples in an OS agnostic form):
Command line switch
/path/to/eclipse -vm /path/to/jdk/bin/javaw
Check this SO answer for an example on Windows.
eclipse.ini
-vm
/path/to/jdk/bin/javaw
Check this SO answer for an example on Windows.