I have fully working Springboot application project in my Downloads directory but when i moved this project to a different directory for example : C:/User/Documents folder its still running but giving me visual errors. it shows the classes are not imported even though they are and application is still running fine
https://i.stack.imgur.com/8Bmuy.png
Im sure what's the reason is.
PS: Im using git. as version control for this project not sure if it is because I initialized the git when this project was in Downloads folder.
If someone knows the solution please let me know.
Thank you
My suggestion would be to:
Close IntelliJ
In your file explorer/finder, go to the directory you project is is now
delete the .idea, .mvn and target folders
Open Idea again and just open the project from the folder again
Likely Idea is just confused.
So from what I understand all classes need to be within a Java project in order to run them. However, when I just downloaded a Java class it automatically opened up in Eclipse outside of a project. Because of this I also cannot simply move it, as Refactor->Move gives the error "the resource is not on a build path of a Java project". So basically because it is not in a project, I cannot move it into a project? Is there a way to overcome this without just copying the class contents into a newly created class?
Edit: also I did not have this problem until a few days ago, when I moved the Eclipse application from a random folder in which it was previously installed, to the program files folder. If anyone could shed a light on why this might have triggered it, and why this predicament was not happening before this would also be appreciated.
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 think Eclipse is trying to make me miserable. A couple of hours ago, my project was working and compiling well. Suddenly that all changed. Eclipse somehow wipes out all changes I have made to my files(activity, manifest etc.) I make sure to save often but when I go to run the project, I get the error that I have a build error. I checked and there was none, so I go to close Eclipse, so I can reopen and see if the errors will go away. Instead what happens is Eclipse wipes clean all my files and I end up with a project on disk with lots of blank code files. I try to run anyway, and I get the error message below.
Failed to read the project description file (.project) for 'com.example.android.nfc.simulator.FakeTagsActivity.FakeTagsActivity'. The file has been changed on disk, and it now contains invalid information. The project will not function properly until the description file is restored to a valid state.
Anyone have an idea what in the world this is about and how I can rectify this?
I would recommend to wipe out all the eclipse related configuration files(make sure you take the backup if you have manually made some changes in those) and import the project again, by following
File -> Import... -> Existing Project into Workspace
Make sure you take the backup of whole project before doing this.
When Eclipse gets stuck in some obscure status, I usually find useful to recreate the .metadata folder in workspace directory. It is a drastic solution, but it usually works for me. After that you can reimport all your projects.
This happened to me because I had a conflict in my .project file. I opened it up in a text editor and fixed the conflict (in my case, removed from ====... to >>>branch..., as well as <<<HEAD) and then I was able to open the project in eclipse.
I was just encountering this same issue (using Zend Studio 12, which is built on Eclipse). My problem was that I was creating a project from a Remote Server, and I was just downloading everything, which also included the .project file from the old project. It wasn't showing this error until I'd closed the program and tried to open it again (which usually wasn't until the next day).
I seem to have resolved it by making sure not to download the .project when initializing the project.
If the .project file is a text file, so if you have it in version control you might want to copy it over from there.
Before you trying the following make a backup of your current project state.
Assuming you don't have an old copy, you can open it in a text editor and try to see if there is something obvious wrong.
If this fails, copy the source files of your project to a fresh location (without the eclipse configuration files) and import it as a new project into eclipse.
if you still have all of your other source (.java files, AndroidManifest.xml, resources), you might be able to get your project back by simply going to the folder containing the project, removing the .project file that you say is now empty, and then using the new project wizard to recreate the project (and .project file) for you from your existing tree of source.
from the menus, select File -> New... -> Project , and then, in the first dialog, choose Android Project from Existing Code .
if you had done anything special to the .project (reliance on specific .jar files or changes to classpath), you may have to re-do these steps after you re-create your project; but at least it should pick up the code you already have.
If all the files are empty, and you have no working Backup, I can't help. I would recommend to use proper version control in the future.
Use git or mercurial, they have nice UI integrations (see tortoisegit/tortoisehg).
To decouple the build process and library management from eclipse, take a look at maven or gradle, this might help you in future projects.
If you use git, complete the merge e.g. del the head in your androidmanifest.
I also got the Same Issue in Eclipse but the real problem is i removed the actual Source project folder from source location (from which eclipse is trying to take the project) to some other place hence my eclipse is unable to get web.xml file since it is not available. Now i changed my source project folder location to the path where eclipse is trying to search for. Issue Resolved for me.
Just delete the 'servers' folder in your workspace and try again.
I'm trying to export a small program that I have made in Eclipse Indigo today to an executable, however, every time I do so one of two problems occur. The program uses one resource which I was hoping to put inside of the JAR but Eclipse will not put in the executable jar no matter which option I tick when I export or which folder the resource is in - the first problem!
The second problem is that whenever I tell eclipse to "Extract required libraries into generated JAR" I receive the following error when I double click on the executable Jar:
Could not find the main class: main.Launcher. Program will exit.
I don't suppose that the second problem is too much of an issue at the minute but the first one is extremely frustrating so I would appreciate any help or advice. Thanks in advance.
(Strangely, and even more frustrating, if I go through the same process with a project I made a while ago with a previous version of Eclipse it works perfectly.)
The folder structure of the project is as follows:
In the project folder there are the following directories .settings, bin, src as default. I have put the resource, which is a png in the bin folder but I have also tried it in the src folder.
Can you give some details?
What is the structure of your eclipse project?
Of what type is the resource?
More important where in the project structure resides the resource file?
Is the folder of that resource file included as a source folder ? (seems to be a prerequiste to get exported to the jar)
Is it copied over to the bin folder when the project is built?
Many Thanks
Michael
Update:
I have built a very simple java project 1 Java class with a main method and put a sample png file in the source folder. I refreshed the project to have the png visible in the project, then I cleaned the project to have it build again, then I ran the Main class inside eclipse. This will give you a run configuration when exporting throught the wizard. Thereafter I exported the complete project as "runnable jar", selected the run configuration and selected "Copy required libraries in a sub-folder next to the generated JAR". The png was included and the Main class was found. The executable JAR could be executed.
(Environment: Eclipse Indigo R1, Ubuntu, JDK 6)
You might want to play through the complete sequence of steps I went through. Maybe eclipse just did not pick up a file or other updates.
regards, Mike
First of all, I would like to thank Mike (marksml) for being so helpful and attempting to provide a solution for my problem. Unfortunately, his answer did not work for me!
I began to look at all of my previous projects and noticed that the one I was having trouble with was the odd one out (because it was the only one that didn't work) and the factor that made it the odd one out, I found to be the JRE system library version. The project was using the JavaSE-1.7 library but when I changed it to the JavaSE-1.6 like my other projects were using it miraculously worked and exported flawlessly! I'm still curious as to why this is the case, but at least I have it working now...
With thanks and kind regards, Andy