Develop Reference

Yet Another 'The project was not built since its build path is incomplete'

I have an Android project that I've been happily building for weeks in Eclipse Indigo. I have not changed any settings, libraries, or workspace components, or added or removed any files. A few hours ago I was doing a "Run as" to run my app on a phone and Eclipse did a hard hang. I couldn't even kill it in Task Manager so I rebooted my PC.
Now when I try to build my app I get
"The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this project"
I deleted gen and did a clean and build with the same result. In the project Properties for the build path, in the Libraries tab it shows
Android Dependencies
Android Private Libraries
Unable to get system library for the project.
Any idea what's going on? This Eclipse "build path is incomplete" error is very common but when I search Stack Overflow and Google, most of the cases seem to be related to importing new projects, moving workspaces, changing libraries or other things I didn't do.
Thanks in advance!

I fixed my problem.
I did a File>Switch Workspace and switched to another workspace that had a different project in it. Then I switched back to my original workspace and everything was fine.
So we can add this to the very long list of folk-remedies, nostrums, old-wives-tales, superstitions and other bits of software lore that accompany the various weird bugs that afflict Eclipse. I sure hope Android Studio turns out to be better than this!

This worked for me:
Open project properties > Java Build Path > Libraries.
Select "Unable to get system library..." > Remove > OK.
Open Libraries again > Add Library > "Android Classpath Container" > Next > Finish > OK.

The following worked for me, so I thought I would share.
Restarted Eclipse and ran into the same problem.
Did the following to get my project to build again.
Right click on project inside Package Explorer and Select properties.
Go to Java Build Path.
Click on Libraries TAB
Remove the line that says "Unable to get system library for the project"
select ok.
Then right click on project, and select "Android Tools" -> "Fix Project Properties."
Hope this helps.... eclipse can be a real PITA sometimes.
BTW I "watched" for any changes after the delete and fix, and it looks like
Is removed from .classpath, and then the "Fix Project Properties" adds the line right back.
Clean + Build works after that.

The resolution was to force a resave of the selected projects (and their .classpath files):
Open the project properties
Select Java Build Path > Libraries
Add a new, arbitrary library (to be deleted later) > OK
Wait for the workspace to refresh (or force a refresh of the project)
The error(s) will go away
Remove the dummy library

Try Project-->Clean. Also make sure "Build Automatically" is checked

"R cannot be resolved" may have wrong build path or libraries import

I know this question has been many times but trust me I have checked all. Most of the question suggests to remove import android.R , remove any error in the xml file, checking name of the files (no capital letters) then rebuild and clean the project or restart eclipse. I have tried all but none solved the problem.
The problem occured when i cleaned all the projects. Now all the projects are showing that error. Since all the project were running perfectly before i cleaned projects, there is no possibility that all of the sudden the layouts or the file names of all the projects have error in them.
Also there is no file in gen folder. As far as i can understand there is something wrong with the build path or preferences can anyne point me in a correct direction? !

Make sure you installed the Android build tool form sdk manager
project right click properties-> Java BuildPath select Library and add android-support.jar the follow these step.
Go to Project->Properties->Java Build Path than select Order and export tab. Set android-support .jar library checked and up it into top of the list. And clean and rebuild..It works for most of the cases

Check the answer here and the thread here. Check if your layouts contain any errors (this has to be done manually or automatically only with Android Studio). Search for incorrectly closed tags like <string> - </string>.
EDIT (taken from this thread):
Cleaning a project removes all auto-generated files. Building the
project it should automatically create them. When you Clean a project,
there's an option to start a build immediately after clean up.
Here's a few things you can try (did the same procedure after manually
deleting the "gen" directory.
After you have deleted the gen directory, go to Project > Clean ...
You should have errors indicating that R cannot be resolved to a variable. Right click on your project from the Package Explorer and
select Build Project. Be sure Build Automatically option is turned off
(uncheck in Project > Build Automatically).
Errors regarding R should have now disappeared. Now, perform a Project Clean once again. All errors should be gone.

Missing AndroidManifest.xml when importing an old Android project into Eclipse

I have an Android project developed on Eclipse (GNU/Linux) that I last touched half a year ago. I am trying to import the project into Eclipse 3.6 on Windows (with ADT installed) installed using File -> Import Project in Eclipse. When the project is imported, I see the following error twice on the console:
[2010-12-10 02:17:12 -
com.android.ide.eclipse.adt.internal.project.AndroidManifestHelper]
Unable to read C:\Program
Files\Android\android-sdk-windows\AndroidManifest.xml:
java.io.FileNotFoundException:
C:\Program
Files\Android\android-sdk-windows\AndroidManifest.xml
(The system cannot find the file
specified)
Why is Eclipse looking for AndroidManifest.xml on the Android SDK path? The file actually seems to be in the project's directory. How do I fix this problem and get the project to compile?

A simple solution is to either reimport the AndroidManifest.xml file or make a change to the file and save it. This worked for me.

If you see an error about AndroidManifest.xml, or some problems
related to an Android zip file, right click on the project and select
Android Tools > Fix Project Properties. (The project is looking in the
wrong location for the library file, this will fix it for you.)
from: http://developer.android.com/resources/tutorials/notepad/notepad-ex1.html

The way you are importing the Android project into Eclipse is wrong. The Correct way of doing is File -> New Android Project. In the Contents Tab in "New Android Project", select "Create project from existing source" and choose the Build Target. That should fix your problem.

It appears that this error is produced because Eclipse thinks the default location for new Android projects is the Android SDK path. Even if the project location is changed, the error fails to be resolved, so the trick is to change the project location before Eclipse is aware of the condition generating the error.
To circumvent this quirk I imported the old project with the following steps:
File -> New -> Android Project
Un-check 'Use default location' and browse to project root directory.
Click 'Create project from existing source'
It's important to do step (2) before (3) otherwise the error persists and prevents running the project.

I had the same problem, all of the above did not work. I cleaned the project and it worked.

Instead of using File ---> New Android Project --> "Create project from existing sources", which will result in the error your are seeing, choose "Create project from existing sample" and choose it from the drop down. This will work.
Experienced JAVA developers tend to go with the first option which is normally there and works for classic Eclipse projects. But this is not your typical project and I bet the Google developers put this special case in the wizard to accommodate the differences.

I had the same problem. I was trying to compile the JakeWharton view page sample, so I checked out the GIT in a directory in a different folder then the workspace which caused the problem.
Eclipse was maintaining 2 folders:
1. A new workspace folder was made under the workspace directory, which eclipse checks for libraries and others source code including the AndroidManifest.xml file
2. The existing folder which was not under the Root workspace
To fix the problem after importing I had to manually move the files in the new workspace folder created by eclipse.

I met this problem when using Facebook SDK, now I solve it by doing this:
Close the project;
Copy "AndroidManifest.xml" file to the project's root path;
Open the project and refresh it, it's Done!

this worked for me by the way:
I changed the project name to the exact name of the project that I am importing.

Eclipse seems somewhat fragile in its naming conventions. One of the causes for this error is a difference between the project name and the folder name in the workspace. I imported a zip file for a project named "HelloDialogs" into a workspace folder named "HelloDialog". This caused the "AndroidManifest.xml file missing" error. Once I renamed the folder correctly, everything worked fine.

Because of the multiple different answers here, I thouhgt I'd add yet another one that worked for me, as I had exactly the same issue when first working with Phonegap android dev tools.
So I found (as mentioned by Gintautas in comments to the accepted answer), that I had to create a new project using the phonegap 'create' script, then when importing the project into eclipse. the only way to get this to work successfully was if the project was originally created in some temp folder somewhere other than the place I actually want to work with it.
So I created a project in windows like this in a cmd window...
c:\phonegap\phonegap-2.6.0\lib\android\bin>create.bat c:\temp\android_boilerplates\test app.test test
Then I imported the project in eclipse like this...
File > New > Project
Within the new project wizard select: "Android Project from Existing Code"
Click "Next"
Now navigate to the temp location of your project and set that to the root directory, check the project you want and check "Copy projects into workspace" as the example below...
Click "Finish"
And that's it, Eclipse should copy all your project files into your workspace and there shouldn't be any errors in your project (fingers crossed).
Your project should look something like this...
Hope that helps, it took me an age to work out why Eclipse didn't like creating a new project from existing code when the new project was being setup in the same place as the existing code. This isn't a problem for other languages I've used, so it was a little weird, but understandable as Eclipse (I'm guessing) seems to want to overwrite certain files.

Eclipse randomly decided to make another folder instead of the one that i had specified, but doesnt have any resources or data or layout etc in it..
it has some conflicts i guess..
anyway, a noob approach to this was, copying the original file to some other location(i put it to desktop)..
now create new project-create existing project, select this one from desktop, n VOILA.. its all fine.. :D

I am a little late to this game but I caused this same problem by generating the initial application into the exact location I was going to work on it. That is to say I put it directly into my current workspace. I then did File, Import, Existing Android Code Into Workspace. The import process blanked out my android.xml file.
I tried above solutions and had no joy. I then generated the initial application into a temp directory and imported from there. This worked for me.

The only way to import a project into eclipse workspace is to create an empty project and then drag and drop all the folders and files into this project. Why is this so is beyond me.
The answer from Raunak is wrong.

I found a .classpath file in the root directory of my Android project. I opened it and updated the file paths in it, and it seemed to fix the problem for me.

I had the problem when I tried to update an old project with recent code from the SVN. I had the Manifest.xml exported to my local file system as backup and deleted it. I've then reverted my complete project to the most recent version from the SVN and then it worked :)

This is what I had to do to get this to work. Fortunately I had backups of earlier "project".
1) Import the project as usual.
2) If the errors with empty xml etc. comes up, close the project.
3) Go to the original project if you have backup.
4) Copy all of the projects root files and directories and paste it over where Eclipse expects the projects root directories and files to be.
5) Open the project and refresh. Make "Clean" if necessary and you're done!
Always make backups because Eclipse f--kups! I learned this the hard way when suddenly my Android project refused to work because of empty manifest-file.

Sometimes if you automatically fix imports in MainActivity IDE imports android.R class instead of one that will be generated for the project. Remove the import and recompile.

when importing project from another workspace add existing project in workspace. and tick to the copy projects in workspace.then check the api level and supporting library from project.properties files.then rebuilt project and clean it.. it is works for me.

2017 Solution: Much Easier and tested solution is to remove your application folder from elipse project only then Import it again and the problem will be fixed immediately!

java missing required source folder: 'gen'

I just reformatted my computer. I have windows xp sp3 32 bit.
I install java jdk
android sdk
eclipse ide
When I go to make a new android project i get this error.
Project 'HelloAndroid2' is missing required source folder: 'gen'
Please help i'm new to eclipse so give detail responses.

I just got this problem when I was trying to import a project that was originally created with a version of the SDK that is no longer installed on my machine.
Right click the project. Select Properties. Go to Android. Select a Project Build Target. Click Ok. You might have to clean and rebuild the project as well.

Right-click on the "gen" folder in Eclipse and select Properties. Then, remove the "Derived" checkbox. Then clean the project.

Most likely, there is a problem with one of your resources, preventing R.java from being generated in the gen/ folder. You should have error messages in your Console related to this problem.

Delete the "gen" folder. Then clean the project. Then build the project again. In my case it worked.

try this...
Right click on the project in eclips
Android tools -> Fix project properties
its works for me

ok , here's what worked for me:
delete the project and make sure you are not deleting it from the disk!
import it again and it will solve the problem.
Good luck....

My case was: I imported Zhou Weikan's cocos2d-android and the error emerged. The most straight-forward solution that came to my mind was to create the folder (right-click on the project in Package Explorer -> New -> Folder and then create new folder named 'gen'. It worked in my case.

delete the gen and its content and clean the project again.

Go to project
Right Click
New Folder (Res)
In my case it works Fine

I tried all these things and none of them worked. One day all my projects are running, next day all my projects have an empty gen folder?
After a series of tests to resolve the phantom missing R.java, the one that led me to a drastic action is when I looked at the Properties > Android and the Project Build Target was greyed out and the project wasn't linked to any SDK, almost as if there were no SDKs installed. This was after I uninstalled 4.2 and reinstalled all tools and SDKs...
Long story short, after trying everything I could find online, I just deleted the whole "adt-bundle-mac-x86_64" folder in my workspace folder, unzipped the original download, and dragged the original folder back into the workspace.
This works as a last resort, however you will have to import all of your projects back into the package explorer by New > Project... > Android Project from Existing Code, and make sure you have the "Copy projects into workspace" UNCHECKED.
IMPORTANT: You will find that you can't do this if your "MainActivity" file is always named "MainActivity," so just for future project creating, it's good practice to always name your main activity something different each time.

This error occurred when I tried to graphically add a grid layout. Deleting the grid layout folder fixed the problem for me.

My solution was to install android sdk build tools with Android SDK Manager.
The probkem was that whenever I clean the project, the gen directory becomes empty.
Hope it will help!

if gen folder or R.java file is not generated then first check error in XML file and make sure android menifest.xml is present.

Right click on the project> Properties> Android > use the latest API
takes care of everything!

In my case, the solution was downgrading the target from android-22 to android-19 at project.properties

Eclipse - HelloWorld - Android error?

I created a Hello world app but get this strange error:
The project cannot be built until the build path errors are resolved
I haven't changed the project, jut created it and tried to run it.

to avoid that annoying problem i have 3 solutions that worked for me.
Solution 1)
delete your generated R.java file
inside your gen/ folder
Solution 2)
a)Delete your project from Eclipse
(i said ONLY from Eclipse, uncheck option: Delete project
contents on disk)
b) import your project to Eclipse:
file > Import > Existing Projects into
Workspace (Look for your project
previously deleted from Eclipse) >
Finish.
Solution 3)
make Solution 1 then Solution 2

It is either a spurious message you can solve by forcing Eclipse to recompute its library paths
I found the resolution for this at Scott D. Strader's blog.
To summarize the solution I only needed to add a library to my project and then remove it to force Eclipse to perform the necessary actions to resolve the problem. I would post the detailed steps here but I don't want to steal his content.
The resolution was to force a resave of the selected projects (and their .classpath files):
Open the project properties
Select Java Build Path > Libraries
Add a new, arbitrary library (to be deleted later) > OK
Wait for the workspace to refresh (or force a refresh of the project)
The error(s) will go away
Remove the dummy library
Note: as the OP mentions, a simple restart of the IDE can be enough.
Or you actually miss one critical library like a JRE library:
I needed to add the JRE library to the project for it to run. Not sure if this was due to the updated version or something else…. Any way this fixed the issue:
Project > Properties
Java Build Path
Libraries tab
Click add library
Select JRE System Library
Next
Finish

Sounds like you are missing an import or a jar. In your project in the project explorer there should be a red x on the file icon that contains the error.

In addition to the listed answers, there is one other scenario I've seen this error appear when using the sample projects included with the Android SDK. For some reason, the generated R.java file can be invalid or corrupt. You can get around it by expanding the "gen" folder in the Package Explorer and deleting the R.java file. It will immediately get regenerated and the error goes away.

Right click on your project, choose "Build Path", "Configure Build Path" -> and choose Android 2.2, or that target you specified when you created your project

I have had similar issues. for me simply closing the emulator and re-running the project works