Develop Reference

Eclipse Luna - Project is not showing up - Strange

I just installed Luna. I imported 3 projects all went well for a while.
Then I restarted eclipse and now it shows only two projects. I tried to import the missing project, but it says it already exists in the workspace.
I closed all other projects and pressed Ctrl+Shift+T to see if it still shows up the types from that invisible project. Yes, it shows files from that invisible project. I opened one of the files and selected Show In Project Explorer. Nothing happens.
Also, in the code when I press . after an String object, nothing shows up.
Seems to be strange. Any help?
Also, if I can do fresh import of all projects, that would help too. But again, I don't know why context assist is not working. I can try importing everything afresh. For this, what are all the eclipse related folders / files I need to remove?
Edit
this helped me with workingset / missing projects. But when I press . after an object, nothing comes up.

For others benefit, it has to do with Working sets. You can click Down arrow in Project Explorer and select "Edit Active Working Set". In the window, on the left hand side, you can see your non-visible projects and move it to right hand side to make them show up under active working set. HTH.

Regarding the problem where Eclipse says it "already exists in the workspace": I recently had a similar problem and I fixed it by unchecking the box that says "copy projects into workspace" and then hit refresh and it should work.

Just fixed this issue by clicking 'Deselect working set' ( under dropdown in project explorer ). For me, 'edit Active working set' was disabled to start with.

It sounds like the projects exists on the file system in the workspace directory, but the actual project got deleted or never imported in the eclipse workspace. Take a look at the workspace directory, all three projects should be there. You can delete the "missing" project from the file system and reimport it again.

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.

Can't Export Android Application in Eclipse

I'm experiencing some strange behavior in Eclipse. I'm trying to export my Android application, which is a game that is written using AndEngine, the open source game engine. Not sure if that is relevant.
Anyway, there are no errors in my project or the library dependencies of Android. I have been running the application on my phone with the debug build for ages. Now I want to export a signed application, and it won't work! (It did used to).
I right click my project, click Android Tools > Export Signed Application and right when I do that, two errors show up that say,
No .class files were found in project "AndEngine" so none of the classfile basechecks could be run . Does the project need to be built first?
No .class files were found in project "AndEnginePhysicsBox2DExtension" so none of the classfile basechecks could be run . Does the project need to be built first?
How the heck do I fix this? I have done a Project > Clean, open and closed Eclipse, open and closed the individual projects. And again - this error is NOT there until I go to export the app! What the heck!

Ok I think I figured this out. Not sure of the "real" issue, but my workaround for the time being is to right click my project in the file tree on the left, then click Properties. I selected the "Android Lint Preferences" in the dialog that comes up, and just hit "Ignore All". Now I can build without the error.
While this is a work around, I'm not thrilled about leaving that disabled completely. I'd like to know which Lint preference i can specifically disable. (I, quite frankly, don't even know what lint is)

I solve this problem turning off Build Automatically in Eclipse before export.

Are those projects set as libraries?
Open Project -> Properties.
Click Android on the left.
Scroll down and make sure under Libraries that "Is Library" is checked.

probably just add:
<issue id="LintError" severity="ignore" />
to your lint.xml config file.
In eclipse probably just set this one (LintError) error to ignore.

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.

Eclipse - Project contains error(s) but none seen

My project has been running fine for weeks. I went to swap out an image today and suddenly eclipse highlighted my project saying it contained errors but did not point to any particular files. I then cleans the project and now it is bringing up the message
R cannot be resolved to a variable
The gen folder is empty and I have these errors now over all my src folder. Does anyone know what to do?
All help appreciated.

Your project has an error and can not build thats why Android compiler can not generate the R class and eclipse warns you about that class. Check out all problems in the problems view. Also check project runtime and library settings if there is anything missing. You might accidentaly delete a lib or java runtime might have been changed.

When I encounter this king of 'weird' issues with *.xml resources I add one more item. I case of strings.xml I add new item and that CTRL+S the project will be rebuild and the R class will be refreshed. This usually fix the problems, and afterwards I delete the item that I added.
There are a lot of times when eclipese doesn't rebuild until you add something new (that it , until you make a change in your resources)
I hope this will help you if not , it might help to someone else having similar problems

If you did not disable the built-in Source history in Eclipse (right click on a file in Explorer view, then select Replace With -> Local History), revert to the code prior to your change, and rebuild. If it builds, figure out what the change was and adjust accordingly.
If you don't have that history, try to remember from memory. Likely it can't build the R file because one of your XML resource file is incorrect or references the wrong file.