I have a java project with dependencies from a Maven private repo. Upon initial set up maven built the project correctly but now projects from the private repo have to be built manually/ locally( mvn clean install -U in the project used to work). When I try to run the project, everything compiles correctly, however upon runtime I get a java.lang.NoClassDefFoundError. These are all from Maven private repos that need to be recompiled locally for the project in question to run.
There are two things that happened around the same time: 1) I had to update my password to the Maven Private repo, however, I updated my credentials stored locally on my computer and when I try mvn clean install -U I can see the dependencies downloading correctly. 2) I am new to Java / Intellij and when trying to delete a class file I accidentally deleted the entire module. Not sure if this broke some link somewhere I may just not be aware of?
I've cleared the cache, deleted the entire .m2 dir contents and started from scratch, deleted the entire project directory and restarted again but still get the same issue.
It might happen when you have duplicate libraries . Please check the maven dependency tree. You should get an insight. You can use tag to remove the duplicate jars.
<dependency>
<groupId>sample.ProjectA</groupId>
<artifactId>Project-A</artifactId>
<version>1.0</version>
<scope>compile</scope>
<exclusions>
<exclusion> <!-- declare the exclusion here -->
<groupId>sample.ProjectB</groupId>
<artifactId>Project-B</artifactId>
</exclusion>
</exclusions>
</dependency>
Related
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.
I am new to Maven Project. I am making changes to one of the open source maven project. I am facing a problem in adding a library to the project. So far i have done this :-
I added a library named jni4net.j-0.8.8.0.jar to the resources folder of the project.
I right clicked the jar(in Intellij) and clicked 'Add as library'.
Then in the pom.xml i added:-
<dependency>
<groupId>jar.0.8.8.0.jni4net</groupId>
<artifactId>jar.0.8.8.0.jni4net</artifactId>
<version>0.8.8.0</version>
<scope>system</scope>
<systemPath>${basedir}/src/main/resources/jni4net.j-
0.8.8.0.jar</systemPath>
</dependency>
But when i build this project(build is successful, test cases are running) and use this it throws following error:-
java.lang.NoClassDefFoundError: net/sf/jni4net/Bridge
Please help me resolve it. I am new to maven and pom. I have looked at various answers, but not getting it right.
PS - I named groupId and artifactID as just reverse of jar file
This is not the right way to add that dependency.
All you need is:
<dependency>
<groupId>net.sf.jni4net</groupId>
<artifactId>jni4net.j</artifactId>
<version>0.8.8.0</version>
</dependency>
The dependency will be retrieved from Maven Central when you build.
Using <systemPath>...</systemPath> is highly discouraged as it usually ties your project to a local environment.
Since jni4net.j dependency is available in maven central, You don't have to download and put the dependency manually. Maven will download and store the dependency locally in `'.m2' folder. Just add dependency as bellow.
<dependency>
<groupId>net.sf.jni4net</groupId>
<artifactId>jni4net.j</artifactId>
<version>0.8.8.0</version>
</dependency>
I'm currently learning java and want to create a project, using maven, hibernate and MySQL. I know that in order to use any of the artifacts with maven, I should find it on mvnrepository and add it to pom.xml. The question is where can I get the list of mandatory dependencies for each artifact I use, f.ex if I need hibernate, I found hibernate-core 4.3.8.Final, proceed to this link and can see it's dependencies in section "depends on". Should I add all of them into pom.xml also?
Well, I think you know about maven.
And yes, You should include all the dependencies with version on your pom.xml files (Which is the main file for all your dependencies ).
First, you need to identify all required dependencies and add on pom file.
While executing code, It primarily tries to get that dependency from local repository (.m2) And if it doesn't exists then it downloads from it's web repository.
Link: maven setup
How it works??
Suppose, You are using log4j for loggin.
You need to know the log4j Maven coordinates,
for example
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.14</version>
It will download the log4j version 1.2.14 library automatically. If the “version” tag is ignored, it will upgrade the library automatically when there is a newer version.
Declares Maven coordinates into pom.xml file.
<dependencies>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.14</version>
</dependency>
</dependencies>
When Maven is compiling or building, the log4j jar will be downloaded automatically and put it into your Maven local repository.
All manages by Maven.
How to find the Maven coordinates?
Visit this Maven center repository, search the jar you want to download.
Hope, It will help.
Thanks.
I've got a maven project that has a dependency that it gets from a remote Nexus repository. I believe that the dependency was not built with maven, and just uploaded with a barebones POM file. The layout on the server looks fine though, so it was probably deployed with maven.
When maven downloads the dependency to my local repository, it downloads the jar file, but doesn't get the POM. At build time, there's a warning that the POM couldn't be found, and no dependency information available. I'm not actually using any of its code directly (it's actually a transitive dependency), so build completes successfully.
The real problem arises when I try to perform site generation for my project. The part that tries to generate the dependency graph report fails, because it can't find the POM for this dependency to work with.
I can't figure out why I'm not getting the POM downloaded, when the jar file for it gets downloaded just fine.
The POM file for that particular dependency looks like this (you can see why I don't think it's built with maven :))
<project>
<modelVersion>4.0.0</modelVersion>
<groupId>com.company.component</groupId>
<artifactId>my-artifact</artifactId>
<version>1.0.1</version>
</project>
You'll notice that the root <project> element doesn't contain any namespace or schema information. Could this be related? Could it be Nexus not recognizing it as a POM? Apart from the possibility of some small syntactical character missing or mistaken, this is my current train of thought...please don't let it influence any ideas you may have! :)
Also, while troubleshooting, I've pasted the contents of the remote POM file into the correct file location in my local .m2 repo. Everything works fine when I do that. This isn't an acceptable fix though, because we will need the build to be done on our CI build servers.
Any help/suggestions greatly appreciated!
Edit:
I've managed to temporarily solve my actual problem, but the strangeness here still exists. I solved the problem by explicitly excluding the thing that depends on this from the dependency that's in my pom (the trouble dep is two steps away at least, and I'm not using anything that uses the thing that pulls it in):
<dependency>
<groupId>com.company.utility</groupId>
<artifactId>shared-utility</artifactId>
<version>1.2.3</version>
<exclusions>
<exclusion>
<groupId>com.company.common.component</groupId>
<artifactId>thing-that-puls-in-bad-artifact</artifactId>
</exclusion>
</exclusions>
</dependency>
I've created a dummy project to prove it, with the following POM:
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.company.project</groupId>
<artifactId>my-project</artifactId>
<version>0.0.1-SNAPSHOT</version>
<dependencies>
<dependency>
<groupId>com.company.component</groupId>
<artifactId>bad-artifact</artifactId>
<version>1.0.1</version>
</dependency>
</dependencies>
</project>
Now in ~/.m2/repository/com/company/compnent/bad-artifact/1.0.1/, I've got:
_remote.repositories
bad-artifact-1.0.1.jar
bad-artifact-1.0.1.jar.sha1
bad-artifact-1.0.1.pom.lastUpdated
With no actual POM file.
If you look inside of _remote.repositories, then this file probably contains information which says "downloading the POM failed last time, don't try it again."
That's one of the things where Maven's policy "don't try to download releases again" gets in your way. Try to delete the folder ~/.m2/repository/com/company/compnent/bad-artifact/1.0.1/ and run Maven again to see the error.
It's quite possible that Maven refuses to use such a broken POM since the root element doesn't have the correct XML namespace. But it's hard to tell without seeing the actual error message.
A way to fix this is to download the JAR and to use mvn install:install-file from the command line to install the dependency locally. Even better, you can use mvn deploy:deploy-file to deploy it to your own Nexus server so all other developers now get a "good" version of the POM.
You should also get in contact with the people running the remote Nexus server so they can fix the issue.
Not related to your actual problem, but with maven (at least, recent version), generated jar contains their pom.xml in the META-INF/maven folder of that jar.
You should try to run maven with -e -X, and move your local repository to force Maven to download all, again.
mv "~/.m2/repository" "~/.m2/repository.old"
mvn -X -e dependency:tree
[edit] it was initially a comment, but it will be too long:
As far as I understand your problem, I think it is an error on Nexus, and not on your machine. Any valid solution would require you to mess with that your company Nexus. If you don't have permissions to do anything with your Company Nexus, you can test it with a local Nexus.
You can also enforce use of that Nexus in your ~/.m2/settings.xml like this:
<mirrors>
<mirror>
<id>nexus-local-central</id>
<mirrorOf>central</mirrorOf>
<url>http://localhost:8081/nexus/content/repositories/central</url>
</mirror>
<mirror>
<id>nexus-local-any</id>
<mirrorOf>external:*</mirrorOf>
<url>http://localhost:8081/nexus/content/groups/public</url>
</mirror>
</mirrors>
You should not lose too much time as to why it fails, but focus on making it working.
For that, I think you should write a valid pom.xml for that artifact, and redeploy it on the server using the pomFile option:
mvn deploy:deploy-file -DpomFile=valid-pom.xml -Dfile=foobar.jar -Durl=http://nexus:8081 -DrepositoryId=company-nexus-deploy
Or if you are too lazy (or if this command fail), do it from the Nexus GUI!
PS: the Nexus default admin login/password are admin/admin123, and I think there was also deploy/deploy123 for deployment. Most Nexus that I've seen were not configured to use another login/password.
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.