The case:
I have created a complex java project (spring boot) with maven build in IntelliJ and I was able to run it, everything was working fine. Now, as IntelliJ hasn't a community edition with spring boot, I had to move to vs code. I didn't change anything in my project, I just opened the folder (which contains the pom.xml and the src folder) in vs code and let vs code load the java project (earlier I installed all the extensions like spring boot, java, etc. for vs code).
After vs code opened the project successfully, I wanted to run it in the main method by clicking the run text (I inserted the image, that you can see the folder structure):
But as stated above, I get the famous error. I reloaded the window, I cleared the workspace, I set the JAVA_HOME and CLASSPATH variables in the env variables and tried, tried, tried it again, but no success. What the hell can I do on top of that? It worked in IntelliJ, it should work in vs code too. I use java se17. Note, that if I start a new simple project, the program get's compiled and executed without any error.
Another curiosity is, if I try to load the maven dependencies, vs code says, that it can't create the dependency tree, but if I run the mvn dependency:tree command, I get all the dependencies and it says, that the build was successful.
What is going on here?
EDIT: my antivirus program blocked maven, so, the problem with the dependency tree is now gone, but the error with the classpath remains.
Anytime I try to run a java file by clicking run, it instead tries to run the class file and thus gives a no main method error.
When I try to right click on a java file and run that, it doesn't recogize it as a file that is runable.
I am still able to run programs from the command prompt but I would prefer to be able to run them in IntelliJ.
This occurred after trying to create a Class path when using JSon Libraries.
Edit:
Normally it shows java files with this icon:
But instead it's showing this icon for java files:
I think the change in icon might have something to do with it.
Edit 2:
the exact error I get is "C:\Program Files (x86)\Java\jdk1.8.0_181\bin\java.exe"...bunch of other program file locations
Error: Could not find or load main class sample.Main
Process finished with exit code 1
I had the same problem and found out that my src wasn't marked as Sources Root. To change this:
right-mouse click on your src
navigate to "Mark Directory As"
choose "Sources Root"
It will now recognize your files correctly and your main classes will be able to run again
IntelliJ not recognizing my .java-files
Problem solved
I had a similar problem.It wouldn't pick up ModlServer in any project. (Not just limited to the one I had open).
I had to file -> Manage IDE Settings -> Restore Default Settings
Note: I lost all my live templates, fonts, etc so just a heads up.
I restarted my computer and that somehow fixed it.
My issue was that I have multiple modules for my project and the module I was working on (where java files were not recognized) was not included in the main pom. I just added that module in the main (project) pom and it worked.
Right click on the project and click 'Add framework support' all directories and classes should now be the right type.
I've fixed this at Intelij2023 by using JDK17 as the JDK the IDE uses to import java source files.
Mind this JDK version does not need to be the same you use to build your project.
Go to: Settings > Build, Executio, Deployment> Build Tools > Maven > Importer
Set the JDK For Importer to zulu-17
I'm using zulu-17 as JDK for imports and coretto-8 to build the project (having JDK version 8 seems to be preventing intelij to properly recognize the project structure)
If you are using Maven or Gradle, try to re-import the project and see if that helps. Could be that your IDEA project has some incorrect settings in it set by mistake, so this way those would be removed.
I am using Intellij for my project development(Java). Strangely, whenever I try to run the project making some new changes to it, Intellij is always running old class files which were complied for a older version of my project. I tried recompiling, rebuilding, tried invalidate caches and restart, removed the project and opened it again but nothing seems to work. Not able to figure out the reason and now I am clueless what to do.
Any help would be appreciated. Thank you.
I've had the same issue and I haven't been able to consistently make it go away, however, here's some things I've tried that could help:
delete .class files
invalidate caches and restart
check settings: sdk and source path imports of IDEA code might affect it
delete and reinstall intellij
Or do what I've ultimately done, which is to create a new project and avoid spending 5 hours tinkering with IntelliJ to get it to run my code properly.
Follow these steps to let IntelliJ "forget" all old internal files:
Close the running IntelliJ instance.
Delete the .idea directory of your project.
Open the project like a new project.
After that you have a fresh IntelliJ project that probably needs some configuration (as usual).
I had such a problem in IntelliJ by a maven enabled project.
Running maven clean phase and ... , but no effect,
any change to classes had no effect in deployed project.
finally I found the problem.
classes was hidden in this path:
{Project Path}\src\main\webapp\WEB-INF\classes{my packages}
by removing this, problems has gone.
Hope it was useful.
In my case it was the maven issue within Intellij settings. When I used bundled version it gave the error it should have. I don't know why giving actual path won't work but Bundled Version will work.
In the context of Java Parser, I needed to run mvn clean install -DskipTests after each change on the command line. Then, class changes were available in IntelliJ. No other way helped here.
I have a maven project which I have downloaded from this link. When I make a couple changes to it, it runs perfectly from the command line when I type:
mvn clean install tomcat7:run-war -Dmaven.test.skip=true
in the directory to which the zip was extracted. (The only 2 changes required to make it work on the command line are to 1.) add a plugin tag for tomcat 7 in pom.xml and 2.) create a context.xml file in the webapp/META-INF folder. Everything else in the app remains the same as the github verion, and the app runs fine from the command line using the command given above and then typing the url in the browser.)
However, when I import the project into eclipse as an existing maven project, and then try to run the app, the app starts throwing errors related to not finding a couple of jars which are clearly in the repository. The app no longer compiles from the command line, or from eclipse. I even tried to run the app as a maven build from eclipse and even changed the maven instance eclipse uses to the freestanding maven that works from the command line instead of the embedded maven in eclipse, but the app still threw the same errors when I tried to run it.
But then, when I repeated the steps with a fresh copy of the app, the fresh copy runs fine from the command line, while the copy that eclipse touched does not compile by any method.
It seems that eclipse has made some changes to the app in the process of importing it as an existing maven project into eclipse. How can I locate the specific changes that eclipse has made to the app? I would like to be able to use eclipse as my IDE, but I cannot do so unless it can compile the code.
This answer was originally posted as a comment it turns out that resolved the OP's problem, and as He asked I'm turning into an answer.
First set your eclipse to use the JDK instead of the JRE. Just as a reference this configuration on Eclipse is Normally on Window->Preferences...->Java->Installed JREs:
Second (as you already did) change eclipse maven to look at installed maven that runs on the command line again.
I've encountered some problems with maven running with the JRE instead of the JDK. Try it and let me know. I will sleep now. Tomorrow I will see what happened.
When trying to start my JUnit-Test out of Eclipse, I get a "ClassNotFoundException". When running "mvn test" from console - everything works fine. Also, there are no problems reported in Eclipse.
My project structure is the following:
parent project (pom-packaging)
Web project (war-packaging - my JUnit-test is in here)
Flex project
Configuration project
edit: How can the class not be found? It's a simple HelloWorld-Application with no special libraries.
Here's my JUnit's run-configuration:
alt text http://www.walkner.biz/_temp/runconfig.png
Testclass (but as I said; it doesn't work with a simple HelloWorld either...):
import org.junit.After;
import org.junit.Assert;
import org.junit.Before;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import biz.prognoserechnung.domain.User;
import biz.prognoserechnung.domain.UserRepository;
import biz.prognoserechnung.domain.hibernate.UserHibernateDao;
public class UserDaoTest {
/**
* the applicationcontext.
*/
private ApplicationContext ctx = null;
/**
* the user itself.
*/
private User record = null;
/**
* Interface for the user.
*/
private UserRepository dao = null;
#Before
public void setUp() throws Exception {
String[] paths = { "WEB-INF/applicationContext.xml" };
ctx = new ClassPathXmlApplicationContext(paths);
dao = (UserHibernateDao) ctx.getBean("userRepository");
}
#After
public void tearDown() throws Exception {
dao = null;
}
#Test
public final void testIsUser() throws Exception {
Assert.assertTrue(dao.isUser("John", "Doe"));
}
#Test
public final void testIsNoUser() throws Exception {
Assert.assertFalse(dao.isUser("not", "existing"));
Assert.assertFalse(dao.isUser(null, null));
Assert.assertFalse(dao.isUser("", ""));
}
}
I've come across that situation several times and, after a lot of attempts, I found the solution.
Check your project build-path and enable specific output folders for each folder. Go one by one though each source-folder of your project and set the output folder that maven would use.
For example, your web project's src/main/java should have target/classes under the web project, test classes should have target/test-classes also under the web project and so.
Using this configuration will allow you to execute unit tests in eclipse.
Just one more advice, if your web project's tests require some configuration files that are under the resources, be sure to include that folder as a source folder and to make the proper build-path configuration.
Carlos approach helped!
Eclipse - java.lang.ClassNotFoundException
Try to check the classpath of the junit run configuration:
Open your run configurations
Click on the jUnit-Test you want to start
go to the classpath tab
Try to add a folder (click on user entries, click on advanced, click on add folders, click on ok and search the outputfolder for your test classes(those you find under projektproperties java build path, source))
works for me.
your build classpath is correct, which is why you can compile. the classpath for your JUnit needs to be checked. go to the Run menu and choose 'open run dialog.' in there you should see a tree on the left with JUnit as an option. open that node and find and select your test. on the right pane you will see a tab for classpath. take a look to ensure that your class that the test is trying to instantiate would be found.
edit:
this seems to be an issue with maven and its behavior after a release changed the default Eclipse output folders. i have seen solutions described where
placing maven into the bootclasspath ABOVE the jre works, or
running mvn clean test does the trick or
refreshing all of your eclipse projects, causing a rebuild fixes the problem
going to your project and selecting Maven->Update Configuration solve the problem
with the first three, there were reports of the issue recurring. the last looks best to me, but if it doesnt work, please try the others.
here and here is some info
Enabling [x] Use temporary JAR to specify classpath (to avoid classpath length limitations) inside the Classpath tab of the Run configuration did the trick for me.
If your project is huge and you have lots of dependencies from other sibling projects and maven dependencies, you might hit the classpath length limitations and this seems to be the only solution (apart from making the directory to you local maven repo shorter (ours already starts at c:/m2)
The problem might be missing the class file in your build folder. One solution is clean the project and rebuild it.
There are many convoluted suggestions here.
I've encountered this problem multiple times with Maven projects after moving resources around by drag 'n' drop, or performing refactoring of class names.
If this occurs, simply copy (not move) the problem Test Case (.java) via terminal/file browser to another location, right-click -> Delete in Eclipse and choose to delete on disk when given the option, move/copy the copied file to the original file location, then select your project in Eclipse and press F5 to refresh resources.
This is quick and easy to do, and has fixed the problem permanently for me every time.
This was my solution to the problem. Of course, many things can cause it to occur. For me it was that Maven2 (not the plugin for Eclipse) was setting the eclipse profile up to use a different builder (aspectJ) but I did not have the plugin in eclipse./
http://rbtech.blogspot.com/2009/09/eclipse-galileo-javalangclassnotfoundex.html
Cheers
Ramon Buckland
Sachin's right:
Even with correct class path, the problems tab will show that some dependency or the Resource/project has error that needs to be fixed in order for maven to automatically build and create classes when you create or make a change in your test class.
"Hi,
Its very Old Jul (which year) but I had the same problem .
Actual issue found that eclipse was not able to generate class file for the java file , classpath was proper.
See the problem tab and check if your project is missing something/file. you can create a new proj and add files one by one and build them until it stops compiling and creating classes ( check the workspace/proj/bin/package/ folder for classes )
its wierd but true , ecplise was failing in compliation because 4 of 20 java files were using a single image which was missing. and as result none of the java file was compiled .
CLASSPATH is not a issue here."
We had the exact exception (using SpringSource Tools, tomcat, on Win7) and the cause was that we had refactored a filename (renamed a file) from SubDomain.java to Subdomain.java (D vs d) and somehow it collided though SpringSource was showing the new name Subdomain.java. The solution was to delete the file (via SpringSource) and create it again under the name Subdomain.java and copy-pasting its former content. Simple as that.
I had the exact same problem but I figured it out! Go to your project file and right click on it, then click Refresh or hit F5. Then try and run it. If it still doesn't work then just forget it, as I had the EXACT same problem and it just means you version of Eclipse is garbage.
JUnit test from inside eclipse gave me also NoClassDefFoundError.
Running 'mvn clean test' from command line gave me following error on several jars:
invalid LOC header (bad signature)
Deleting these jars from local m2 repository and running 'mvn clean test' again
solved my problem.
click on project->properties->Java build path->Source and check each src folder is still valid exist or recently removed. Correct any missing path or incorrect path and rebuild and run the test. It will fix the problem.
All I did was Properties -> Java Build Path -> Order and Export -> Enabled all unchecked boxes -> moved Junit all the way up
Tried
Link : [here][1]
Open your run configurations
Click on the jUnit-Test you want to start
go to the classpath tab
Try to add a folder (click on user entries, click on advanced, click on add folders,click on ok and search the outputfolder for your test classes(those you find under projektproperties java build path, source))
worked after
Maven 2 LifeCycle >> test
I had tried all of the solutions on this page: refresh project, rebuild, all projects clean, restart Eclipse, re-import (even) the projects, rebuild maven and refresh. Nothing worked. What did work was copying the class to a new name which runs fine -- bizarre but true.
After putting up with this for some time, I just fixed it by:
Via the Run menu
Select Run Configurations
Choose the run configuration that is associated with your unit test.
Removing the entry from the Run Configuration by pressing delete or clicking the red X.
Something must have been screwed up with the cached run configuration.
I had the same problem. All what I did was,
i). Generated Eclipse artifacts
mvn clean eclipse:eclipse
ii). Refresh the project and rerun your junit test. Should work fine.
while running web applications Most of us will get this Exception. When you got this error you have place .class files in proper folder.
In web applications all .class files should sit in WEB-INF\Classes folder.
if you are running web app in Eclipse please follow the steps
Step 1: Right click on Project folder and Select Properties
Step 2: Click on "Java Build Path" you will see different tabs like "source" , "projects", "libraries" etc
Step 3: select Source folder. under this you will see your project details
Step 4: in the "Source" folder you will see Default Output Folder option. here you have to give the classes folder under WEB-INF.
just give the path like projectname/WebContent/WEB-INF/classes
the structure depends on your application
please do remember here you no need to create "classes" folder. Eclipse will create it for you.
Step 5: click on "OK" and do the project clean and Build. that's it your app will run now.
I solve that Bulit path--->libraries--->add library--->Junit check junit4
Usually this problem occurs while running java application java tool unable to find the class file.
Mostly in maven project we see this issue because Eclipse-Maven sync issue. To solve this problem :Maven->Update Configuration
I suggest trying adding this to the VM arguments;
-verbose:class -verbose:module -Xdiag
Then you can debug it from Eclipse which should print out some message like;
java.lang.ClassNotFoundException: org.adligo.somewhere.Foo
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:398)
at java.base/sun.launcher.LauncherHelper.loadMainClass(LauncherHelper.java:760)
at java.base/sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:655)
From this you can set a breakpoint on LancherHelper.java 760 to debug the Eclipse Lanucher itself. In my case I noticed that user classpath appeared to be null, even though I have many jars in it in the Lanuch config.
Make sure if your test class working before , but you facing issue all of sudden. then clean your project and build it again. Make sure project has been configured in build path as read above article.
Well, you can solve this problem basically by creating a new project.
Close the project (save the code in another folder on your computer).
Create a new project (add a new final directory and do not leave the default directory selected).
Remake your previous project adding the code saved before.
This happens because probably you created a project and didn't select a directory/folder or something like that.
I hope had helped you!
Please point to correct JDK from Windows > Preferences > Java > Installed JRE.
Do not point to jre, point to a proper JDK. I pointed to JDK 1.6U29 and refreshed the project.
Hereafter, the issue is gone and jUnit Tests are working fine.
Thanks,
-Tapas
I've run into a same error in Eclipse recently, i.e., the Eclipse IDE couldn't find the Unit test class no matter how I change the configurations. Learning from the previous posts here and in other web sites, I've double checked and triple checked the classpath and source info, and move up and down the source folder and libraries, in both the "Run Configuration" and the "Java Build Path" config windows, and I've also cleaned the Project and rebuilt it, but none of the tricks work for me. The specific Java project is an old ANT compiled project and have lots of jars included in Eclipse library.
Then, I changed the unit test class to add a main() method and right click it to "Run As" a Java Application instead of JUnit test, and suddenly, Eclipse seems to wake up and identified the class correctly. Afterwards, I switched it back to a Unit test application, and it is still working.
This seems to be a bug in Eclipse, I am guessing the large number of libraries (>260) may confused the JVM's ability to locate my JUnit class.
I was hit with this issue also and was able to come up with a sufficient solution for my case. If your Eclipse project has a .classpath file in your project root (see it in Navigator view instead of Package Explorer view), be sure that your Maven classpathentry appears prior to your JRE Container classpathentry.
<?xml version="1.0" encoding="UTF-8"?>
<classpath>
<classpathentry kind="con" path="org.maven.ide.eclipse.MAVEN2_CLASSPATH_CONTAINER"/>
<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
</classpath>
If your project does not have a .classpath file, you can edit your project's Java Build Path to switch the Order and Export. If your project has the .classpath file and you only change your ordering in the Java Build Path, you will see that the ordering is not impacted and the issue will continue to occur.
And a project->clean never hurts things after you make the change.
Make sure your test launch configuration does NOT contain the following lines, OR try enabling automated Maven dependency management.
<stringAttribute key="org.eclipse.jdt.launching.CLASSPATH_PROVIDER" value="org.maven.ide.eclipse.launchconfig.classpathProvider"/>
<stringAttribute key="org.eclipse.jdt.launching.SOURCE_PATH_PROVIDER" value="org.maven.ide.eclipse.launchconfig.sourcepathProvider"/>
I tried everything I read in this long post and, incredibly, what worked for me was, rather than clicking on the test class and selecting Run as JUnit test, clicking on the test method and running as JUnit test. I have no idea why?
Deleting the project from eclipse (Not from hard disk) which in a way is cleaning the workspace and reimporting the project into eclipse again worked for me.
Changing the order of classpath artifacts in the Java Build Path resolved it for me.
Right Click on the project and go to Project Build path.
Go to, Order and Export tab and move the JRE system library to after the sources.
This should fix it.
JUnit 4.4 is not supported by the JMockit/JUnit integration. Only
versions 4.5 or newer are supported that.