It is possible to run a project, which contains errors in Eclipse.
I think it is normal for project with many files to contain some erroneous files to fix in the future and still be able to run it.
Unfortunately, I can't find this possibility in IntelliJ.
Methods proposed in this answer IntelliJ Idea, run code regardless of errors in unrelated project files do not work for me.
It throws ClassNotFoundException in the class with main. Class itself contains no errors and was running under Eclipse. There is no apparent appropriate *.class file in target/classes directory.
In your run configuration, you can tell it not to make before running.
You can compile individual files through their right-click menu or (from memory) Ctrl+Shift+F9 if the file you want to compile is in the editor.
A combination of these two will mostly achieve what you want, although this is probably the key paradigm difference between IntelliJ and Eclipse, and you'd be using IntelliJ in a sort of non-IntellliJ way (if you see what I mean).
Related
I am currently facing problems when using JUnit 5 in VSCode.
I noticed that as soon as the "junit-platform-console-standalone-1.7.0-M1.jar" is in my library folder within my project I can run my tests but I can not run my main method any more ("Error: Could not find or load main class"). As soon as I remove the .jar I can immediately run it again.
The problem also occurs when I use the default project with no-build tools.
I created a simple test class and let the .jar file automatically download via the "Testing" explorer (enable Java Tests Button). Now that the .jar file is downloaded, the tests work but the main method doesn't. If I remove the .jar out of the folder, the main method works again but obviously the tests aint.
Any solutions so I can run both? Thank you in advance!
Without knowing more about your project, here are a few workarounds that might help:
Reload VS Code and run F1 -> Clean the java language server workspace.
Add the mainClass and sourcePaths configuration in your launch.json file.
Check your folder/file name and make sure the file path is in plain English.
This can also cause problems if you have the Code Runner extension installed. You can try to uninstall it, then F1 -> Clean the java language server workspace.
Hope this helps you.
This error is just bizarre, my code compiles fine, I can see there are no problems with it, yet this error has just popped up. I have tried re-starting NetBeans and there is no additional exception information.
What can cause this?
If it is Netbeans, try to uncheck "Compile on save" setting in the project properties (Build -> Compiling). This is the only thing which helped me in a similar situation.
I guess you are using an IDE (like Netbeans) which allows you to run the code even if certain classes are not compilable. During the application's runtime, if you access this class it would lead to this exception.
It's caused by NetBeans retaining some of the old source and/or compiled code in its cache and not noticing that e.g. some of the code's dependencies (i.e. referenced packages) have changed, and that a proper refresh/recompile of the file would be in order.
The solution is to force that refresh by either:
a) locating & editing the offending source file to force its recompilation (e.g. add a dummy line, save, remove it, save again),
b) doing a clean build (sometimes will work, sometimes won't),
c) disabling "Compile on save" (not recommended, since it can make using the IDE a royal PITA), or
d) simply remove NetBeans cache by hand, forcing the recompilation.
As to how to remove the cache:
If you're using an old version of NetBeans:
delete everything related to your project in .netbeans/6.9/var/cache/index/ (replace 6.9 with your version).
If you're using a newer one:
delete everything related to your project in AppData/Local/NetBeans/Cache/8.1/index/ (replace 8.1 with your version).
The paths may vary a little e.g. on different platforms, but the idea is still the same.
I also got the same error and I did clean build and it worked.
Add selenium-server-standalone-3.4.0.jar. It works to me.
Download Link
Recheck the package declarations in all your classes!
This behaviour has been observed in NetBeans, when the package declaration in one of the classes of the package refers to a non-existent or wrong package. NetBeans normally detects and highlights this error but has been known to fail and misleadingly report the package as free of errors when this is not the case.
I had the same issue with one of my netbeans project.
Check whether you have correctly put the package name on all the classes. I got the same error message because i forgot to put the package name of a certain class (which was copied from another project).
Disable Deploy on Save in the Project's Properties/Run screen. That's what worked for me finally. Why the hell NetBeans screws this up is beyond me.
Note: I was able to compile the file it was complaining about using right-click in NetBeans. Apparently it wasn't really compiling it when I used Build & Compile since that gave no errors at all. But then after that, the errors just moved to another java class file. I couldn't compile then since it was grayed out. I also tried deleting the build and dist directories in my NetBeans project files but that didn't help either.
Organize your code as a maven module.
Once done run the command from terminal
$mvn installl
to check if your code builds fine.
Finally import the project in netbeans or eclipse as maven project.
change the package of classes, your files are probably in the wrong package, happened to me when I copied the code from a friend, it was the default package and mine was another, hence the netbeans could not compile because of it.
I had this problem with NetBeans 8.0.1. Messages about problem in project deleted class. Deleting the ~/.netbeans didn't work. Also I looked for ANY reference to the deleted class in ALL my projects, nothing found. I deleted the build classes, everything. Then, when I started Netbeans again, compile and magically appears the message in Run and into the mother compiled class. I tried the uncheck "Compile on save" Dime solution, and works, but it's not practical.
Finally, my solution was edit and force recompile of the mother class. This way the new .class doesn't contains the message and Run works OK.
Just check the packaging, the simplest answer I can provide is that your package has been mislabeled (within a class).
Also, you may have some weird characters. Try white-flushing the code in a Notepad (or Gedit) and then pasting it into a newly created class with your IDE.
If you are using Netbeans, try to hit the Clean and Build button, let it do the thing and try again. Worked for me!
I had the same problem. My error was the packaging. So I would suggest you first check the package name and if the class is in the correct package.
Implementing my own functional interfaces resolved this for me (so instead of using java.util.function.* just create your own single-method interface with the parameters and return-type you want).
I am working on a large open source project that is under svn and Maven. As I try to get my head around the various classes and methods contained in the project I realised that I can't search for class names with the usual eclipse search feature (e.g. Ctrl + Shift + T). I can't even modify a class without getting this error:
"This compilation unit is not on the build path of a java project"
.. I kind of guess what that means but I don't really understand why it says that. I mean I just checked out the project from svn and imported it in eclipse like I do usually.
I have also pasted a screenshot to give an idea of where I am in the project when I am attempting these simple tasks.
Can anyone please tell me what is wrong in this project and give me some direction on how to sort this issue?
It seems likely possible that the Subversion files did not include a Java build path for Eclipse and that you have not created one. That will be stored in the .classpath file after you go to Project > Properties and specify the locations of your source folders (possibly among other things, such as libraries).
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.
I have an urgent and puzzling problem with Eclipse. My system crashed on itself this morning, and after I rebooted, I can run a program perfectly within Eclipse, by right-click on the Java file and choose 'Run as Java Application'. However, after I make the project into a .jar file, and execute that, the behavior of the program simply does not reflect what the code does.
I have checked that I am compiling the right project, and running the same code from the same project within Eclipse does not cause any problem. And btw, I am using a plug-in called fat jar to compile the .jar file, if that makes any difference. I have used the same plug-in numerous times before to compile the very same project, and never had any problem.
Does anyone know what might be causing this weird/inconsistent behavior of Eclipse? Do I need to re-install Eclipse and fat jar to fix this? Thanks.
My usual procedure for strange things like this is,
A) Clean and build again i.e. Project -> Clean
B) (not so eclipse related) Since I am usually using a build tool, do the same thing from the tool to ensure its eclipse.
C) If it gets really bad, I'll start a new eclipse workspace and try from there.
D) Iff I had just installed a new plugin before things went strange I'd think about reinstalling
It sounds extremely strange :)
But Eclipse can, and has, acted strange before. I have had problems in both Java, C++ and PHP development during the years that could only be fixed with a resinstall of Eclipse. You could probably fix it by digging around, but the time it takes to find and fix these types of strange problems in Eclipse is simply not worth it.
Good luck!
Please try to Reset Perspective first (Before reinstall eclipse)
Window->Reset Perspective.