I'll keep it short.
I have a project in eclipse using Marvin, the Marvin's jar is added correctly in the build path, classpath.
The problem is, whenever me or someone else exports the project from github and open it in eclipse they have to edit Marvin's Jar path in classpath or to re add it.
I tried to search everywhere for a solution.
Is there one? I don't know. Something like:
new File("src/file.txt")
And then using file.getAbsolutePath() and getting the entire path including the directory (D:\project\src\file.txt)
You can switch to an external build tool, like Maven or Gradle, that will download it for you on whatever machine you're on, or make your Java Build Path reference portable by using a classpath variable that you then manually assign on each Eclipse workspace.
I set a lookAndFeel synthetica theme for the project.After that it is not working(jar file in the dist).
Again I removed it and tried.Then it worked. I did clean and build.
Tried several themes. They all workedd in the project. But did not run in the dist.
What should I do? Please help me..
I have experienced this before in my projects. Most of the time it happen because of using icons and images.
When /Icons/calculator.png image in your package, it is not wrong in netbeans like this getClass().getResource("/Icons/Calculator.png").
this is working on netbeans. but not in jar file. you need to rename Calculator.png.
use jar file in console (CMD in windows , shell in linux) with this command
java -jar adress-jar-file/jarfileName.jar
then see error in console.
Just Right click on yoru projet in netbeans and select Set Configuration then Customize in the window that appears provide your Main Class by clicking the browse button or writing it manually and Clean and Built again
Plz make sure some points.
1) You have set main class properly.
Right click on Project-> project properties-> Run-> set Main-Class
2) You have set theme path properly.
3) Your themes are not corrupted.
4) You have build your jar properly.
Right click on project-> clean and build(Note: Do nothing while it finish building jar)
5) Your lib folder not corrupted (if it is present).
It looks like there maybe something wrong with your setup. In your project properties, under libraries have you by chance added synthetica.jar as a required jar. but m not sure try it
but you can simply do,
you could create lib folder manually in your project folder and then paste that jar in that folder then through netbeans go to your project then right click on libraries and then browse to find your project folder open that then click on lib folder that you have created open it then click on jar that you have pasted and that jar file will be added to your project.
I could resolve my problem.I'm sorry that I was used trial version Synthetica.jar. after I bought it and done every thing from the beginning. I resolved it. Thank you for your contribution to resolve it.thank you
I have no idea why, but from today Eclipse doesn't compile .java files into .class. I press the "Run" button and Eclipse only tries to run the program rather then compiles it first, so i get this error all the time:
Exception in thread "main" java.lang.NoClassDefFoundError
open problems view from window -> show view -> problems, if there's any error, fix it
eclipse will reject to compile if there is any problems in your project
Close Project -> Open Project -> Clean -> Refresh
Hope it helps for someone else
This problem happens when "for some reasons" your project is corrupted and has a red icon near the project's name in Eclipse. The solution is to save the project's folder, delete the project in Eclipse, than create the project again in Eclipse coping all the previous files saved.
I ran into this problem with Eclipse Luna, for some reason the Java builder was missing from the project. Verify that in your .project file you have something like
<buildSpec>
<buildCommand>
<name>org.eclipse.jdt.core.javabuilder</name>
<arguments>
</arguments>
</buildCommand>
</buildSpec>
You can also configure builders from Project Properties -> Builders
When I have had this exact same problem, its cause has always been the same and the solution has worked 100% of the time for me. It's caused by a missing jar file in the project's Java build path and it's indicated by a red exclamation point decoration on the project icon. To fix the problem, go to Project|Properties|Java Build Path, click on the Libraries tab and either remove or fix the path for all missing jar files. If your project is configured to rebuild automatically, it should start a build as soon as you apply your changes.
The eclipse needs to erase the output folder when building classes.
The folder is found on Project Properties -> Java Build Path -> Default Output Folder. It can differ from general output folder name found under Eclipse Preferences. If this output folder cannot be erased for some reason (for instance, on Windows, when a shell is opened on this location), the project is marked as corrupted (as Marco Micheli describes) and the classes then are not built.
You just need to make sure the output folder can be erased.
Yes I was facing this issue. Coz Eclipse cannot build the project for Build Path error. Check that your external jar files is not showing any error. Delete the Jar file which one is missing or which one is showing re color. delete that one. add a fresh one from the correct path or location. if all the error are gone. then in the project bin folder one class file will be created and then could not load main class error will be removed too.
there can be errors in your project, or other reasons like mentioned in above answers.
or you may be a fool like me
who moved the source code to other folder and not updated source path in project build properties. in this case it was not giving any error or class files too.
check that too.
goto
Project Properties -> Java Build Path -> Source
Add or Link new source folder location.
Do clean all projects ! This will erase all old class files, so eclipse is forced to generate them again.
Some times jars in the build path might be missing even though we are not using it. Since error is there, java files wont compile into classes.
Can check errors from problems view.
Either remove jars from build path or place the missing jars in the build path.
I had problem in eclipse for load module not found and no class file was getting created.
Solution: Go to Create New Project > Under JRE section Choose Use project Specific JRE.
Now Class files are created.
Please check if all the jars are there in your build path settings.
If any jar is missing this issue might come.
I had this problem, I tried the clean, the build manually, open, closing the project, deleting, and open, etc., nothing works, and after 4 hours I get a workaround what works for me.
Please, Make a RAR, ZIP, or copy from your entire project folder as a backup if it doesn't work and you mess around, OK, now:
Clean the Project. It cleaned all my class files from the output folder, but doesn't generate the class files after the clean with the building (but we already know that)
Delete the project (warning, make sure the Delete contents is not selected or your project will dissapear). For me it says something about that desynchronysation with code mix, and hibernate, blabla)
Close myEclipse
Restart your computer.
Open myEclipse
Import the project with the option "Projects from folder or Archive", not with the "existing projects into workspace" option.
Myeclipse start to build the class files, I don't know why, but works for me, I hope this helps somebody else.
Also ensure that there are no projects with fatal errors (projects with ! symbol over it) in the build path of the project which is not generating classes under the bin directory
Just restart your machine.
Its weird but it helps we had loads of problems this type in our company for unknown yet reason. Always restarting the machine helped.
It was normally encountered while trying to run Junit tests and it could not find a class even when the Run configuration was pointed to /bin.
I encountered a similar problem: previously compiled and running java files couldn't run anymore. Eclipse showed "couldn't find class xxxx". When I checked bin folder, the previous .class files were gone. That's why Eclipse couldn't run the files, NOT because of errors in files. I don't know why it can't just re-compile the file, and why the .class file gone missing in the first place.
But I found a solution:
Simply create a dummy java file in the same package (without doing anything just create), then run it. Then magically all previous .class files came back. And I can run those files as before.
Just Remove Your all Jars (Libraries) from the Build Path and refresh and add all jars and clean and build the project
This is probably a rare event but I declared a servlet with annotations and left off the "/" before the servlet mapping name. I spent over an hour chasing my tail, installing new servers, thinking I might even need to re-install my IDE and it was this simple error! Every time I tried to load any page from my Dynamic Web Project I got a 404 error. I could not even load a plain vanilla html page. There really needs to be better error logging with the IDE and Server interaction as there was zero indication of the error and my servlet was never called at the start of my web app. Hope this helps save someone else some frustration. Always name your servlet with a / slash like /myServlet never just myServlet.
I tried many different potential solutions: cleaning, rebuilding, removing, re importing, Update Maven Project and nothing. I still couldn't run my app from Eclipse. In my case the reason was that I was running Eclipse using openjdk-11 while my project was in Java 8. After I've reconfigured Eclipse to be ran from Java 8 everything started to work (in eclipse.ini).
-vm
/usr/lib/jvm/jdk1.8.0_202/bin
I'll explain my solution to this problem: "eclipse not compiling java files into class files". I'm using Eclipse version '2020-03 (4.15.0)'. I have a project that is dependent on a java project. For the dependent project, I was not able to export a jar file containing the compiles classes and resources. To be more precise, the exported jar file did not contain any class files. The output bin folder for the project is empty after doing a project build. In examining the console output when I tried to build all projects indicated that the build failed because the dependent project was missing. In looking at one of the log outputs, I saw something indicating that the build failed because some eclipse class was missing.
One of the things I tried was to do an eclipse update. Eclipse offered up the list of changes and I tried to apply them, but the update failed. I tried to update several times but they all failed. Looking more carefully at the offered up list of updates I noticed that one of the suggested update involved "deleting" Java Development Tools. That line had an warning indicating that the entire feature could not be deleted due to other dependencies and that only the non dependent features would be deleted. Doesn't that sound suspicious. Why was the update trying to delete Java Development Tools? My speculation is that something got deleted from the Java Development tool that was causing the build process to fail. The missing class I saw earlier also suspiciously sounds like it might be part of the Java Development Tools feature.
So what I did to solve the problem was to reinstall eclipse. I used the eclipse loader application to do the reinstall. (Note, I did not uninstall it first). After the reinstall, the dependent project was able to produce classes, and things once again worked as they should.
I certainly don't know how the eclipse release got into this compromised state, but in my situation the re-install of eclipse was the only way I could find to resolve the problem.
There would be the case : if you have opened project explorer in eclipse then it may not show you classes generated under /**/build/classes, in such case open Navigator view of that project and check build directory under the same project.
I had running project opened in eclipse. After an accidental restart of windows, now when I open the eclipse I see my project is marked with a little red cross. Now when I run the main method I get a java.lang.NoClassDefFoundError.
I have tried restarting eclipse, Project -> Clean but it doesn't solve the problem.
When I checked the project directory, inside 'target' folder there are no compiled .class files. I tried building the project but I can't get the compiled class files, which is the reason for the error.
How do I solve this?
I tried all the solutions here, but here's what worked for me.
First, remove the project from eclipse.
Then, in your project folder, delete the 2 files that eclipse creates. They're hidden, but they're called .project and .classpath.
Finally, add the project back into eclipse and eclipse will recreate those 2 files and a new configuration for your project.
My specific issue was that it a project that was missing a Java Builder because it thought it was a scala project. The only way for me to reset this was by removing the project, deleting the 2 files, and adding it back in.
Maybe Eclipse's workspace files have become corrupted. Restart Eclipse and choose a new workspace folder (or choose Switch workspace from the menu). Then import the project files into a new project.
Try deleting the run configuration and remaking.
If that doesn't work, open the class, ctrl+f11 to run. That will force Eclipse to update its classpaths & rebuild its main indexes.
To delete the configuration:
- Menu -> Run -> Run Configurations.
- Select your configuration
- Press delete or use the delete icon
If you are using maven, this will likely fix it: Right click your project -> Maven -> Update project.. (or alt + F5), select your project, make sure "Refresh workspace resources from local filesystem" is checked and click ok.
My eclipse project has similar issue though the error appeared slightly different. I imported a third party java project into Eclipse, with Project > Build Automatically checked, do a Project > Clean..., no classes were generated in the output bin folder. Tried different options, no luck.
I noticed a red exclamation mark at the top left corner of the project name.
Right click on project name, Properties > Java Build path, I saw "Build path entry is missing: cci/src". Manually created src folder, the red exclamation mark gone. Do a Project > clean..., project compilation successful
P.S. The eclipse project is not properly organized, there are no code under src folder. I suspected src folder went missing while checked in by original author since there are no code there.
Was having the same problem and finally found the glorious hint here.
In my project there is one *.scala File and Eclipse Neon is incompatible with the Scala IDE, thus there is no builder for scala and the whole project is not built.
After removing the Scala file and the Scala Package from the linked Libraries )Project Properties --> Build Path --> Libraries) and afterward re-adding the Java Builder (no idea why this one went missing, but here's a useful help on how to add the Java builder when missing), the project could be built and run again.
Try refreshing and then cleaning the project.
For me the problem is in missing jars,the jars were added first and the location of those jars where changed after.
So When I correctly added all the required jars again to the build path, it starts to build project correctly.
I copied an Eclipse project from my PC (eclipse is on drive D) to the laptop (eclipse is on drive c) but when I try to deploy the agents I have in my project I keep getting the following error:
The archive **D**:/eclipse/plugins/it.fbk.sra.ejade_0.9.0/lib/libjade4/commons-codec-1.3.jar which is referenced by the classpath does not exist.
I changed all the libraries' addresses to the correct ones (C:/eclipse/plugins/it.fbk.sra.ejade_0.9.0/lib/libjade4/__etc__) for all of them by right clicking the project > build path > configure build path... but that doesn't work. I also tried to refresh the project, restart eclipse but still nothing..
Any suggestions?
Thanks a lot!
First make sure that the .jar file is exist in the given path,if so then you can easily try making a new project and copy your material to it, and configure it to the .jar path.
If this doesn't work you may need to remove the temporary files from your project and eclipse on your laptop.
Also, please give more description about what happens on right clicking the project > build path > configure build path ?
Hope everything works well.
I had the same problem and just discovered the solution to this.
Go to project>properties>Java Build Path>Libraries>Add External JARS.
After specifying JAR file at a certain location, you will see it in previous window "JARs and class folders on the build path:" with "JAR_fileName - C:\YOURPATH".
Don't stop here instead click on the "+" button to the left to expand it, and IF it says "Source attachment: (NONE)", you double click it and add the path to the JAR file by selecting Workspace location.
This solved the problem for me.
Had the same problem and non of the above solutions worked.
This is how I fixed it.
go to your project folder
open .classpath file (enable view hidden files if its not showing)
edit the path
delete the project from workspace. Imp: Don't select (Delete project
content) checkbox when prompted. !!!
re-import the same project
I had the same issue...
I was refering jars from a mapped drive, when I moved them to my local drives, it started working fine. Also try giving a shorte path for the jars.