Develop Reference

Sudden weird errors on a project

Today I came to work, happy. But when I opened my Eclipse, I saw that one of my projects has errors.It's weird because it shows that it has errors only in the window bar, and not in the Navigator. I don't have any Java errors, this is a valid project that was fine all the time:
Some of the errors on the error log of Eclipse:
JavaBuilder handling ImageBuilderInternalException while building: SP_Procedure
Cannot connect to VM
File <SomeFile> has been skipped, problem while reading ('Resource is out of sync with the file system')
Unhandled event loop exception
Internal error
When I run an application from this project, I get a warning message but when I proceed, it works fine, but still. It's very disturbing and I'm not sure if it's harmless.
I tried to:
Restart Eclipse
Restart my machine
Clean projects and recompiling them.
Refresh projects
Pray
Nothing helped. What could be the problem? (I'm using Indigo Service Release 2)

The following nuclear option has desperation written all over it. But I have been where the OP has been with the Juno version of Eclipse.
Run a "Synchronize with Repository" and save all of your local updates to a different directory.
Delete the project. (Check the box to delete the contents on disk. Scary step, but that's OK, because you saved it in a different directory in the previous step, right?)
Read in a fresh project from the repository. It builds happily at this point.
Integrate your local updates.
Keep on praying.

Looks that one unused JAR was deleted, but for some reason, I didn't get errors in any file, even in the files that imports this JAR! So what I did was restoring this JAR, delete unused imports and deleted the JAR again.
I've found this error after two days of navigating on this project on each file.. This is weird that Eclipse didn't recognize that1 this is an error, and throw many unrelated errors such as:
Cannot connect to VM
File has been skipped, problem while reading ('Resource is out of sync with the file system')
Unhandled event loop exception
Is this a bug in Eclipse? (All errors and warnings are enabled!)
1 As seen in the image in the question..

A class from the list of imports for the file seems to have moved out or the jar file containing the class is missing.
Expand the imports section and check if you find some classes that are missing but have been imported.

Though it is a pain, sometimes the easiest solution is to back up all your projects (either in a repository or somewhere else on your computer) then uninstall and reinstall eclipse. No it's not fun, but it should reset eclipse so everything works again. The downfall though is that you have to reconfigure eclipse to any special settings you had/reinatall any extra functionality currently installed (eg. android add-on) and reconnect to any repositories you have. While punting isn't fun, it can be effective... I hope you don't have to resort to this though.

I have went through that problem a lot of times, and tried everything you tried. Rebuild, recompile, refresh, remove and add JDK, remove and reinstall Eclipse... nothing worked
The only thing I concluded is that the workspace metadata was corrupted.
What I did (every time it happened) was
Create an empty workspace
Import -> existing projects into worskpace
Mark the "copy projects" (else it will only link them)
Wait for the copy, and start working with the new workspace
If you work with SCM systems (Git, SVN, etc), making a full checkout will do the trick too, but the worskpace import will let you retrieve those changes you didn't get to commit (if any).
It's a little painful if you have somethings already set (like JDK names, servers, etc), but then I realized it was faster than keep searching how to fix the workspace
Regards!
PS : I've been working with Kepler lately, and everything works fine till now

Click Window -> Show View -> Other -> General -> Problems
This view will show you what is wrong.

Did you, by any chance, update your virtual machine outside of Eclipse? I can't help but feel that we're both missing a finer detail here. I just keep seeing "cannot connect to VM" and thinking that it's a major clue.
Have you tried running anything from the terminal? Does it work there?
If so, do you know where your current edition of Java is located? Is Eclipse looking somewhere else?
Is this exclusive to one project? Do you use any additional libraries to the JDK?

Maybe try this for Resource is out of sync with the file system error:
Right click project in Eclipse Package Explorer
Close Project.
Right click project in Eclipse Package Explorer
Open Project.

Other things not mentioned:
project properties > java build path, see if any of those tabs got changed, local file got moved? read/write permissions on some file you are linking to?
project properties > java compiler, see if workplace settings have changed? maybe under errors/warnings, you can systematically set them to 'ignore' until the error goes away to determine what type of error it is?
maybe update some of the eclipse plugins?

I saw something like this happening for a number of reasons. Mainly because of validation in files other Java source code. See if you are validating XML for instance.
Right click your project and chose Properties (Alt+Enter) and Validation to see the related configuration.
As for the danger, I lived with those marks for ages and nothing wrong ever happened.

Eclipse says my Android project(s) contain(s) errors, but there aren't any

Since last night, Eclipse hasn't been letting me run any of my projects and gives me the error "Your project contains error(s), please fix it before running it".
This happens regardless of which project I use.
There are no code errors in any projects
There are no missing files (R.java, etc.) or folders (src, res, etc.)
There are no errors in the console (even on verbose) or the error log screen
I've cleaned all the projects, and each individual project many times
I've restarted ADB, Eclipse, and my computer
I have no idea what to do next, so hopefully its fixable.
NOTE: I am using Git, and this occurred after switching to my master branch to export a new update to one of my apps.
Thank you in advance! (:
Edit 1: I have also tried deleting and re-importing the projects before I posted this.

Click Window -> Show View -> Problems, that should show what exactly Eclipse thinks is wrong with your project. Sometimes you can simply delete the problem from that view, and Eclipse believes you everything is fine (yep, weird, I know).
Also, after you switch branches using an external source control tool (one not integrated into Eclipse through a plugin), Eclipse sometimes won't pick up all changes, you'd need to manually refresh the whole project file tree.
If nothing else helps, try setting up a new Eclipse workspace and importing your project there.

check your build paths - there could be jars and dependencies that are outside of the app that need to be opened or imported.
another trick is to edit an xml file, just change one word to intentionally cause an error, save the file, then change it back to proper syntax and save again. Error magically disappears.
another trick is to edit a java file, (cause error, save, fix error, magically error free)

I had this problem and I have fixed it. My issue was this:
I somehow managed to require another project in my build. That project had errors in it, which I believe is what caused the issue. I think this happened when I accidentally asked Eclipse to fix my build path or something when I was trying to fix a mistake. To correct this issue go to (on mac):
Right click on your project folder in the Package Explorer
In the menu, go to "Build Path"
Select "Configure Build Path"
Go to the "Projects" tab (along the top).
Is there anything in there? If there is and you weren't expecting there to be, select the project that is in that folder and hit "Remove"
This fixed the issue for me. Hope it helps.

I think you need to clean your project. Do project -> clean. Should work fine after that.

Try using Project->Android Tools->Fix Project Properties besides checking for your Android path. Check if your ANDROID_HOME and ANDROID_SDK are set correctly besides adding tools and platform-tools are set correctly in environment variable PATH.
Hope this helps!

Go to your .android folder and delete your debug certificate.
E:\Users\(your profile)\.android
Inside that folder there is a file name 'debug.keystore'. Delete that, clean and try to build the project again. Sometimes this error is caused when the certificate expires.
I found this answer here and it solved my problem ;-)

I think go to project ->clean some error can be solve this problem

Go to Projects in the menu bar
Then check the menu Build Automatically.
This helped for me.

IntelliJ and SVN: "no changes detected" upon commit

I'm trying to share a project between my desktop and laptop using Subversion. The project has 3 modules. I've imported the project folder into a repository in a shared folder that my laptop can access over the network.
I checked the project out on my laptop and then tried to open the project. None of the modules are visible, only the project's .iml file, as in the screenshot below.
I notice that the .iml file has a line for "content url", which refers to a location on my desktop. Maybe this is the problem. What can I do about it? Do I have to create a new project on the laptop and import the modules - so there would be 2 different top level .iml files, one for the desktop and one for the laptop? Am I going about this the wrong way?
UPDATE: The problem seems to be with committing. When I make a change in a file, save, and hit Commit Changes, I get a popup saying "No changes detected". This is the same on both laptop and desktop, and meant that I downloaded the wrong version onto my laptop before. I deleted the repository and created a new one, and my project works on my laptop now, but I can't commit changes from within IntelliJ (only with TortoiseSVN via file manager). Also, when I imported my project into version control from my desktop computer, the working copy wasn't put under version control. So I can't update from my desktop unless I check it out to a different folder.
I think there is something wrong with the SVN plugin with this version of IntelliJ (10.5.1). Does anyone else have problems with committing changes?
RESOLUTION I needed to
1) Update Settings | Version Control to map Subversion to the working directory
2) Import into Version Control
3) Check it out again
It may possibly have been caused by the fact that the modules were originally standalone projects which were in separate repositories. Whatever the cause, IntelliJ's "No changes detected" dialog isn't the most helpful.

VCS -> Refresh File Status solved this for me, when Intellij suddenly stopped noticing changes.

Please refer to the FAQ.
As for the content root, make sure that it's located under the project root or module root, in this case the path will be stored relatively to the project/modile root inside the iml file. If the fixed system specific path is used in the iml, such module will not work on other systems.
UPDATE:
Make an explicit mapping between the actual working directory and Subversion in Settings | Version Control dialog. If you are using the default placeholder and your project files are not under the checkout root, it could be the case.
After performing the initial import you need to do a checkout in order to use version control in IDEA.

Sometimes doing VCS -> Refresh File Status works for me.
Other times, it does nothing.
A solution is to
COPY all your file contents to clipboard / external notepad (for backup)
Choose Rollback on the file which needs updating. Now it is up-to-date with the server and does not contain your new changes.
Edit file again (checkout), and PASTE your original file contents.
Attempt to commit changes. It should detect them now.

I just ran into this today- checked out an existing project and had to update the SVN scheme from 1.6 (I think) to 1.8. That seemed to make Subversion not recognize that it was wrong it its belief- even though I could DIFF and see changes relative to the latest repository version- that "No Changes Detected."
I got so fed up that I shut down Intellij...on a whim I reopened it, and the file in question appeared blue...hmmm...yep, now it detected the changes.

I had the same issue it seems it may have been caused by having a file with the same name in two different GIT-repositories.
I was able to fix it by opening File -> Settings -> Version Control and then un-assigning and re-assigning GIT as the VCS of the two directories which both had the file. First the directory in which there was no changes in the file then the other active one which did have changes (but which did not detect them before).

I got into the similar issue today and I tried VCS -> Refresh File Status, but it didn't help me. When i looked at Version Control->Subversion Working Copies Information, i found an svn error The working copy at /home/project is too old to work with svn client 1.9.4. First i ran svn upgrade and then doing VCS -> Refresh File Status resolved my issue and i was able to commit my changes.

None of the other solutions here helped me.
Ended up checking out the entire repository again, copied all the sub folders over to the newly checked out folder and submitted the changes.
Deleted the old folder and renamed the new folder to the old folders name.

Can't commit to Subversion from NetBeans

When I change some interface things in Java, like the contents of a menu item, and save them, the commit option does not enable. NetBeans does not know that changes have been produced so I cannot commit them. How can I commit them?

Can you commit from the console?
try svn stat in the root directory of your project, that should show you the files that have been modified with an M near the name of the file. if you can see them, run svn ci to commit all changes.
Maybe (and just maybe), svn is ignoring those files on purpose, to check if this is true, run from the console svn propedit svn:ignore .(<- this dot is necesary) in your project root to check if that directory/file/file extension is being ignored.
Good luck!

Are you using Netbeans 6 or higher? If not, you need to tell Netbeans where the svn executable is (see the link and the associated FAQ).
Are you sure that your subversion repository is running on a machine that is in sync with your workstation's view of the current time (e.g., synch-ed via ntp)? If the time is enough out of sync, it's possible that the subversion module is missing the update and, therefore, not flagging the change.
Also, you should check to make sure that you have an active valid connection to the subversion repository. You can easily do this for the file you just edited: right click on the editor tab for that file and choose Subversion -> Diff or Show Changes or Search History. If any of those fail, your IDE has lost its connection to SVN for some reason.
Another possibility is that you didn't succeed with a real checkout: if the .svn subdirectories aren't properly configured, the menu item will definitely be disabled. I would recommend that you right click on the project (under Projects) and try Show Changes. If that doesn't succeed, you don't have a valid Subversion checkout and the Netbeans options definitely won't work.

If for whatever reason netbeans isn't allowing you to commit, I would suggest either doing it from the commandline, or using a program like TortoiseSVN

It is Subversion's responsibility to know what has changed since the last commit/update. If NetBeans' Subversion interface doesn't allow to commit, then it may be a bug in Netbeans. Technically, there should be no reason to disable commit button - Subversion doesn't prevent you from committing even if nothing has been changed.

Right Click the file which is marked as red color, select resolve confilcts
and try to commit now...

In Eclipse, what can cause Package Explorer "red-x" error-icon when all Java sources compile without errors?

I'm using Eclipse for Java development. All my sources compile fine and the resulting application compiles fine. However, I keep getting an "red-x" error notification in the Package Explorer.
All my sources in this source directory (too long for the snapshot) compile fine, none of the show the "red-x" error icon.
Any suggestions on how to fix the problem would be highly appreciated.

yeah, this happens sometimes for no apparent reason. You can go to the "Problems"-Tab (right next to console output) and see the error message, so maybe you can narrow it down that way.

This happens often when I use Maven, and I had always ignored it until I found this question. You need to update the project in this case (figured this out by looking in the Problems pane)
From the project context menu: Maven -> Update Project and select the available maven codebases
Alternatively you can use (Alt + F5) to bring up the same window

Try to clean the project and rebuild it.

After build. Refresh project and if still persist just right click Problems tab in eclipse and choose delete all.
It often happens if you do maven install and eclipse properties files do not get updated properly. Even though your project does not have any errors. Hopefully!

I want to start by thanking everyone that answered. But cleaning and rebuilding was not enough in my case because the problem was still there and needed fixing.
Turned out that one of my package directories had accidentally been copied so that an extra directory now existed called "Copy of dagskra" containing Java files with wrong package declarations. In addition the errors in this "new" directory don't show up with a "red-x" in the package that it exists in:
Snapshot from Package Explorer showing errorous "Copy of dagskra" directoryr http://www.freeimagehosting.net/uploads/a824304b18.png
It was the hint of reading the "Problems" tab :-) that turned me into the right direction, so I'm selecting that answer as the accepted answer because this is what I needed:
Snapshot from Problems tab http://www.freeimagehosting.net/uploads/dea26d5dd0.png
Hoping this will help others...

So upon finding that there could be a missing package in the buildpath, thus the red x against the main project, to remove this:
1) go into "Configure Buildpath" of project
2) Java Build Path -> Source Tab - you should see the red x against the missing package/file. if it no longer exists, just "remove" it.
red X begone! :)

Sometimes there are build path errors in .project, and you need to switch to Resource view to actually see the file that is causing the error.

As others have said, bad file references in the build path is often the culprit.
Usually a .jar file that has been moved/deleted. Eclipse expects to find everything referenced on the build path at the location specified, and will complain if not.

I had the same issue and below steps resolved the issue:
Delete the JRE from PROJECT> properties>java build path> libraries.
Restart the eclipse
Add the JRE again
Rebuild the project using Project>Clean and chose option to build automatically.
Please try.

Subversion is occasionally the culprit for this as well. It might not have anything to do with your environment. But, there might be a discrepancy between the current and local state of the project. In my case, doing an update, and then a commit to the subversion server provided me with the expected clean result without any flags in the project such as the X.

In my case what solved this problem was simply to Close Eclipse and opening it again...However I am still not sure why this happened or why it worked. I was having problems Cleaning my project (it said it could not Delete certain file) and this solved it :):

Try doing a rebuild. I've found that the red x's don't always disappear until a rebuild is done.

I've run into a similar problem many a time, what happens usually for me is that a java file will say it won't compile in the text editor but in the package explorer it will say it's compiling fine.
Sometimes doing a 'rebuild' or 'clean-build' doesn't work, the files don't actually get built (one has to presume that eclipse thinks the files it has are up to date) and when this happens I usually open up the java build path and just move one of my dependencies down/up the pecking order. This forces eclipse to do a rebuild of everything and it always seems to work.
If you're still having problems try copying the project and seeing if you get the same behaviour and at a last ditch attempt post a bug for eclipse, it may take a while for them to fix but at least you know that you're being heard.

To add to the previous answer, an extreme way of "cleaning" your project is to delete it (that is deleting its reference from the workspace, not deleting the actual files), and then re-import it.
Sometimes, it helps...

FindBugs also puts a red-x against files/packages to indicate static code analysis errors.

I have run through this. My case was more involved. The project was packaged fine from maven command line.
Couple of things I made.
1. One class has many imports that confused eclipse. Cleaning them fixed part of the problem
2. One case was about a Setter, pressing F3 navigating to that Setter although eclipse complained it is not there. So I simply retyped it and it worked fine (even for all other Setters)
I am still struggling with
Implicit super constructor Item() is undefined for default constructor. Must define an explicit constructor"

I also experience those misterious error-symbols on packages from time to time. A way to get rid of them that works for me is to effectively remove the JRE System Library from Java Build Path and add it back again.

My solution that finally worked was to clean all projects, close eclipse, clean all projects, close eclipse, and so on at least 5-6 times. Eventually it all settled down and everything was as expected. Weirdest thing ever!!
And no there were no errors in the Problem or console view.
Also this happened after a computer crash. The last time it happened my whole workspace was completely lost. It was still there on the computer, but when I tried to access it, it would be all blank.
For whatever reason computer crashes are really really really badly handled by eclipse.

Also, you may update the project by clicking,
Right Click on project name -> Select Maven -> Right click -> Update Project.
This helped out for me.
Thanks.

This can occur for a number of reasons. If you have changed the jdk, the Project facet will have a red X next to it while no other folders shows an error. If this is the case, modify the jdk that is shown. This happens on occasion in our JAX-WS class (HSG

I solved mine by
Close all other projects (i.e. unrelated project option)
Clean and build
My project was android, and that did it.

This happened when i downloaded fabric.io on Eclipse Mars but Restarting computer solved this problem for me.

i had same problem. I checked "Problems"-Tab and found no server for the project. I defined the server. the red-x disappered

You can go to project-> Buildpath-> Library
If there is any library that is X marked ie [cross marked] removed it and again try to build. It worked for me as well/

I encountered this problem today and found this link. I followed as mentioned by Patrick Schaefer above and opened the Update Maven project Dialog. Click on my working project and selected the checkbox "Force Update of Snapshots/Releases" and 'Ok'. All the red cross vanished.
I hope this helps anybody in a similar situation.

The question is old but I had this issue and I tried the following to no avail.
mvn update (with snapshots)
remove project and re-importing
clean build
restarting Eclipse
changing order of items in build path
In my case I've got multi module mvn projects and one of the nested projects was showing a red X icon only in the Project Explorer (package explorer and problems were totally fine) and the whole project was fine as I could run classes without any issues. So seemed like a display issue.
The only thing that worked for me was to edit the pom.xml if the offending project module and make a breaking change (add 'xxx' to a tag name) which caused 1000s of errors and then undo.

You may clean the project by clicking,
In Eclipse, Right Click on Project -> clean
This helped out for me and saved a lot of time.
Thanks.

Right click on the project with errors, then in the sub-menus select:
Maven > UpdateProject >
and then:
Select the checkbox for all the dependent projects
select force update of snapshots
click OK.
This worked for me..