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IntelliJ maven project generated-sources not picked up (only some)

I've reinstalled my windows machine and installed Java 13, Maven 3.6.2 to finally run my projects. I use java immutable classes which get generated by maven. I have a problem where only SOME generated sources are picked up and some are missing in the editor (shows errors). However, I'm able to run the application through IntelliJ and build with Maven.
Any ideas on how to fix this?
Do note that I've gone through a number of similar questions where ALL generated-sources are not picked up and I have the correct settings for picking up source files.

Kind of a funny situation here... Everything worked fine, but I found that one of the interfaces I used (from which a generated source is made) had another generated source marked as red (as if not imported). Importing the full path for it suddenly resolved the issue.
common.advert.Price getPrice();
My guess this is an editor problem that I have.

Intellij Project some files are not updating on compile

I am trying to compile an IntelliJ project, and have been working on it for over a month with no issues. Today I tried to compile and the changes I made in certain files did not make it into the compiled jar. As if by magic old versions of my code are being built, despite my attempts to completely remove any signs of the old code.
Somehow, refactoring the files to another name fixes it. This suddenly started happening today to multiple projects and I have no idea how to fix it. Help?
I've already tried manually deleting the cache for the application, and invalidating cache in the program itself.
No error messages, although I noticed that the files that refuse to change are blue in color, even after pushing to git.

Remove .idea folder and .iml files. Then open the project from IntelliJ as below.

Changes to my classes in Eclipse are not reflected when I run the project

I recently wiped my disk, but I have numerous backups of all Eclipse-related files. Everything that I need seems to be here, but whenever I make changes to my classes, even after I quit and restart Eclipse, the changes aren't reflected when I run the program. The changes still have been saved in my .java files, but they don't get compiled when I run.
Things I have done:
Project > Clean (numerous times)
Project > Build Automatically is checked
I tried building manually several times to no avail
All my hot code replace options are enabled
Downloaded a fresh copy of Eclipse
Restored my old Eclipse folder from before the wipe
I should be using the same settings as before, back when everything worked, and I haven't changed any operating procedures. The project is a simple game, nothing outside the box. I checked the build path, the only things there are the old class files.
So that's my situation. Thoughts?

Not sure the reasoning behind why it happens, but a quick fix is to copy the class to a separate project, then copy it back. Fixed the issue for me.

java.lang.ClassFormatError: Absent Code attribute in method that is not native or abstract in class file "name of class"

I know this question may seems stupid since i cannot give a lot of infos about it, but I think that the problem has to be some kind of bug...
I have written a java program whith NetBeans 7.1, which now gets me this error when trying to run. 10 mins ago it was perfectly running, and i have changed nothing to the class the error refers to
Could this be some kind of NetBeans error? Maybe it is a well know problem?

It also got this exception in NB 7.2
'clean an build' and restarting NB didn't work
updating NB with the latest updates and performing 'clean and build' also didn't work.
So i renamed the cache directory:
c:\Users\userabcd\AppData\Local\NetBeans\Cache\7.2\index\
started NB, waited for it to finish 'background scanning' and pressed 'Debug project' and voila. The cache gets corrupted every once in a while :-/

EDIT: Added Solution B below.
Solution A:
Project Properties
Build >> Compiling
un-check: Compile on Save
Clean and Build
Notes A:
If you leave Compile on Save un-checked, you won't have this problem any longer for this project.
If you enjoy the benefits of the Compile on Save feature, you can re-check the option after you clean and build, and continue work on your project as normal.
Compile on Save is meant to save time by constantly recompiling your .java files into .class files in the background as you save changes to your source code. That way when you build or run your project, most of the compiling work has already been completed allowing you to run and test your code quickly, even for large projects.
NetBeans uses some fancy caching and versioning to avoid having to recompile your entire project every time you save a file. That's why the other solutions listed here will often work; they are ways of defeating this caching-and-versioning system when it occasionally fails, as it has above.
Solution B:
Create empty folder e. g. C:\Temp\mine
Create a new shortcut for NetBeans
with command line parameter in Target:
"C:\Program Files\NetBeans 8.2\bin\netbeans64.exe" --userdir "C:\Temp\mine"
When compile errors occur
(ClassNotFoundException, MethodNotFoundException, etc...)
delete C:\Temp\mine\var\cache
Notes B:
You'll lose all your NetBeans settings the first time.
Much easier to solve future compile errors caused by caching bugs.
Allows running multiple copies of NetBeans, one per userdir.

I got also this exception. My solution was:
edit and save mentioned class (.java file)
clean & build project
deploy to tomcat server

I just had this happen to me with Netbeans 7.4 Beta.
Things I tried:
Restarting Netbeans.
Clean and build.
Shutting down netbeans, renaming the cache dir, starting netbeans and waiting for scanning to complete.
What worked for me:
Making the source file writable and saving a meaningless change (inserting a space).
I don't know why any of the other steps didn't fix the error. Maybe it would have worked if I had done a clean and build after renaming the cache dir?
Its a very frustrating situation to be in - Hopefully this helps someone (perhaps a future me?).

The JDK says for ClassFormatError:
Thrown when the Java Virtual Machine attempts to read a class file and
determines that the file is malformed or otherwise cannot be
interpreted as a class file.
Perhaps a class file has become corrupted. I am going to do the standard IT support statement.
Have you tried restarting NetBeans?
Hope that helps

Got right the same thing with Netbeans 7.1.
Working on a project that works fine for several months.
Now I changed a bean which gets persisted with javax.persistence and now this exception got thrown. Reverted my few changes, clean and compile the project, reboot the whole system: still exceptions.
The curious thing about it: the generated .war works perfectly in a Tomcat at another machine.
UPDATE:
Today I got the same problem again and I couldn't recall how to solve it, but I found this post again. ;)
After a half hour I found the solution: Just change value of the property serialVersionUID, redeploy the app and then you can change the value to its original value and redeploy again -> working.
Seems like Tomcat is holding that class somewhere deep inside – deleting working directories didn't led to success.

Re-building a deleted class file in Eclipse

I accidentally deleted a .class (Java bytecode) file in my project (on the filesystem, not using Eclipse itself). Easy to fix, right? Just re-build it. But that doesn't work! Even if I select "Build Project" or "Build All" or "Build Automatically" from the "Project" menu, nothing actually happens on the file system, and I still get:
Exception in thread "main" java.lang.NoClassDefFoundError
I just want to re-compile this from the source code I already have!
By the way, when I choose "Clean..." from the "Project" menu, Eclipse doesn't delete any files either. I have also tried re-importing the project into a different folder, but Eclipse just copies all the .class files and the problem persists.

The OP answered his own question in the comments (2 and a half years ago):
Found the solution: another project on which that project depended could not be compiled, because it could not be cleaned, because Eclipse wanted to delete the .svn directories throughout that project (I have no idea why), and it could not because some of the files didn't have write permission. I was happy to wipe out all the .svn data just to get this working! Thanks for the hint. – user690075 Sep 7 '11 at 1:25
In regards to the bounty
This question has not received enough attention.
This problem keeps wasting hours of my time.
IF the OP's answer didn't resolve your issue, you should ask a more specific question on a new post, describing what you've attempted and how the OP's solution didn't resolve your specific issue.
That being said, assuming you did try the solution the OP posted, it is possible a different issue (that wasn't caused by deleting a class file) is causing the same error. Because you started a bounty on someone else's question and you can't get your prestige back I thought it would be appropriate to mention it might be worth your time to make sure your JDK version(s) are compatible between old or external source code used in your project. You'll get the same error NoClassDefFoundError when the compiler reaches a point in your code that references an object/class that's defined in a library that was developed on an incompatible JDK, it's missing key internal dependencies that are not found within your JDK version.
I would go into more detail, but since this question is specifically about an error that came about from deleting a class file I don't feel it's right to do so.

Do a complete clean
1) Find and delete the .eclipse folder (you may back them up first)
2) Delete related .class files
3) If there are any .svn folders, delete them either manually or via your svn client
4) Do not use auto build for this, but manually select only the broken project and do a clean (in case there are dependencies)
If that fails, probably a good idea to package your source codes and re-import as a new project. That can avoid wasting time on a probable IDE bug

In more traditional languages, programs are loaded all at once as part of the startup process. Java doesn’t have this problem because it takes a different approach to loading. This is one of the activities that become easier, because everything in Java is an object. Remember that the compiled code for each class exists in its own separate file. That file isn’t loaded until the code is needed. In general, you can say that “class code is loaded at the point of first use.” This is usually when the first object of that class is constructed, but loading also occurs when a static field or static method is accessed.
If You can't restore from local history. Then you are out of Luck. Use Source Control Management Tools like SVN or Git to avoid such surprises next time.
If you are having source file try to compile file along with dependencies alone in console or other IDE and copy that class file let the errors be errors now edit source file in eclipse try to build again. Hopefully this will not work because even eclipse will neglect Re-compiling some files while building Project. Better Give a Try.

You sure this source file is in your project's source set? Because Eclipse will only compile and put it in your classpath in that case. Right click the project in Package Explorer, Properties -> Java Build Path -> Source. The enclosing folder should be there or Eclipse won't compile it.
In case, say, this source file of yours was once in source set and was compiled that could explain why it was working up until you removed the binary.
In order for this problem not to happen I suggest having Scrub output folders when cleaning projects being selected in Java -> Compiler -> Building and Build automatically... on in Project menu.
Also make sure your project compilation/build succeeds, otherwise Eclipse may not compile all the classes.
If it still doesn't help it could be important what type of project you are having problems with: Java Project, Maven Project, Gradle Project, etc.

To the person that put the bount out, maybe you could just commit all your changes to what ever code repository you have, after exiting eclispe just delete the whole workspace, then create a new workspace and re import all the files into the new workspace from your code repository.