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My R is gone and can not be recreated

What i did:
I downloaded: XYPlot and added the jar to my libs folder
I added this example: Quickstart to my project
I startet the App: Everything worked
I closed Eclipse
I opened Eclipse
My R was gone
What i tried to fix this problem:
I restarted eclipse
I cleaned the Project
I deleted the Project from Eclipse and reimported it
I used Android-Tools to fix the properties
I checked if there are uppercase letters in some Layout-Files or Drawables, etc.
I also checked all other invalid characters.
I made sure that there is no other R imported by any of my files
Nothing solved the problem
My min and target sdk:
<uses-sdk
android:minSdkVersion="13"
android:targetSdkVersion="19" />
Does someone had the same issue? Where is R located and how can i recreate it?
Ok i figured out that even when i create a completely new project the R of
the new Project cant be found. What is going on there?

You probably have a typo (unclosed tag, missing hyphen, comma, dot or other error like wrong package name in the manifest) somewhere in one of your XML files, either in the manifest.xml or in strings, or layout. Check them.

R file doesn't gets recreated whenever there is some error in the code, since the xml files present in the values folder don't get auto-checked for errors so generally the problem lies in those files.

A resource exists with a different case

I'm unable to build my android app due to a strange error:
Description Resource Path Location Type The project was not built due
to "A resource exists with a different case:
'/ProjectName/bin/classes/com/Name/ProjectName'.". Fix the
problem, then try refreshing this project and building it since it may
be inconsistent ProjectName Unknown Java Problem
My file structure is the following: http://pastebin.com/6P6mEftD
I checked for files that had almost the same name and I couldn't find any. This was marked as the solution in a previously asked question that described the same error.

I had the same "resource exists with a different case" error.
The fix I had to make was in the AndroidManifest.xml file. My "package" parameter in the manifest XML tag did not exactly match the package name in my Java files. I suggest you look in the manifest XML and see if you spot the naming issue there.

I just had this error and I studied a lot to solve it.
Here it goes:
All answers you might find, may be correct because there're differents causes for it.
To solve this issue, you must look into the "R.java" generated in the "gen" folder.
Once you opened it, look for two class that has the same name but is written with different cases. Example (mine): "String" ... "string"
Then, you will figure out that you miss spelt some thing. You never use Upcase letter to call strings at the xml file.
Example: android:contentDescription="#+String/imageView2"
DO NOT write string with capital S.
use:
android:contentDescription="#+string/imageView2" instead.
Once you locate the string you need to find where you put it with the find command.
Once you correct the "grammar", just clean your project.
Pease.
TMA.

Try to remove the bin folder and "Clean project".

I had this problem.
I follow Pauland and I deleted my bin folder. But nothing happened. Then I close the project and it openned with no errors anymore.

Assure Package name has exactly same in Android Manifest and in the sources

I copied project 'src' files from one project to another. In there I made a mistake in renaming the project folder as (com\company\projectName). The project folder name is expected to be all lower case. Then I deleted the bin & gen folders and rebuilt the project. All set.
Hope this helps.

I fixed it by removing all files under the target directory and letting the automatic rebuild execute.

I modified my AndroidManifest.xml but somehow it was rolled back when I tried to rebuild.
Than I tried edit class name from gen folder using 'Refactor > Rename'.
I changed my class name from xxxxLib to xxxlib (lowercase).
It solved my problem.

1_ match "package" parameter in the manifest XML tag exactly with the package name in Src Java files.
com.example.myapp is not com.example.MyApp
2_ delete all things in Gen folder
3_ Project -> Clean
enjoy :)

My problem was the incorrect package names defined in AndroidManifest.xml file, remember the packages name are case-sensitive, then just a Clean > Build Project
update: sometimes is necessary a "hard reset" of the project deleting the folders /gen and /bin, then Build Project

R.java file is not generated?

I am working on an app which was working fine .
I tried some new layout files but when I build the project the R.java file is not generated .
I tried clean and build project but still the file is not generated.
Why is this happening?
What should I do now to regenrate the files?

Android will not generate the R.java after a clean if any of the XML files have errors in them. Check for any errors and fix them. R.java will then be built.
If that doesn't work, sometimes Eclipse looses track of the file. Click your project and hit F5 to Refresh the project.

R.java file is automatically generated in application. If you want to know why your R.java file is not generated then there are some problem into your last layout file made by you.
If there is illegal according to android OR if there is any error in XML file then R.java file will be deleted.
Thanks.

Try refreshing your project. Right click on your project folder in the project explorer, and click on the Refresh option

In my experiences, Eclipse ADT will not show every errors in package window, e.g. Asia characters file names, and system-config-file from Windows. Sometimes, you have to re-import your project after check and remove these files.

I tried the following. Consider the application name to be "My First Application". Then the name of the package should be com.xx.myfirstapplication.yy. Make sure that you add a yy after the application name in the package field while creating the application. Hope it helps.

Check if you have main.xml file in the menu folder, but don't have in strings.xml
<string name="action_settings">Settings</string>
Sometimes that is the reason in my case.

So I realize this question has already been answered. However, I had the exact same problem today and was stuck on it for about an hour. I have come up with a different solution that solved my problem. The XML did not have any errors/typos in them.
I was trying to get the Google Wallet example to run.
My solution ended up being that the android:minSdkVersion (in the manifest file) was set too low. I simply raised this value and all errors were gone.

Magic behind R.java file

Recently I have been having quite some problems with R.java file. Now I have decided to do a backup and delete the file to see what happens.
Nothing happened, so I created an empty R.java file and hoped for the best. Now Eclipse seems to figure out that the file was tampered with and even issues a warning:
R.java was modified manually! Reverting to generated version!
And that's all there is. I tried building it manually but got no results.
So, I have two questions:
what should I do to force Eclipse to regenerate the file
what is happening here? How is the file created, where is the code that is generating the file?
I would appreciate any help. As usual the problem occurred just a few days before the deadline :)

I had a problem getting my Android app to compile, with seemingly inexplicable errors about failure to generate R.java.
The problem was caused by my previously killing the Android emulator during the build. Don't do that! A clue was the appearance of several left over *.out.xml files.
The solution was to select the project, click Project->Clean, and then manually delete all the *.out.xml files. Only then could I click Run->Run and have a successful build.
One more thing: I'm using Eclipse. I had to make sure that the project was selected in Package Explorer, and not just some random source file. Easy to not notice!

R.java is autogenerated on build. It's content is based on the resource files (including layouts and preferences).
When you deleted it, it was recreated, but if you create your own, you will get into trouble as the build system will not replace it.
You can simply delete it again (manually or by choosing Project->Clean) and rebuild your program.

I had this problem several times, and most of the times it is caused by some mistake in the "res" files, check everything is OK in all your res files, mainly XML, and after you can built.
For example, two common causes of this problem can be:
Didn't properly spell the name of a property in a Style in a XML file.
Didn't properly close a string in the XML of a locale file.

I found the problem - I have created a 9patch image with the patch area defined only on the Y axis (I was trying to prevent resizing on the other one).
The question remains: Why isn't there a warning about the error? Or if there is - where is it buried?

Sorry, but try to check the output in Eclipse. May be you have some errors that prevents Eclipse to finish build proccess(check your AndroidManifest.xml, is it correct?).I mean, that you should check all your resource files(string.xml, layouts, ...) and interfaces(*.aidl), may be there are some problems(inconsistent syntax, or something....) that prevent eclipse to generate R.java.

I had the same issue and it was that I had named a resource file (a .png image) using uppercase letters. (ImageButton001.png instead of imagebutton001.png).
Afther changing the name of the file my R.java came back.
Rgards,
Juan

If there's insufficient free memory the build tool will silently fail (Eclipse will not show any errors or report anything in the error log). Close your other open applications (e.g. the emulator and browser) then add a space to the application manifest file and save it.

As ponkin stated - you probably have one single problem that causes R not to re-generate itself, because of which you now have one million and one problem.
Do not try to create R class yourself. Try to think of the last XML you've been messing with, and check it for errors
I've had the same problem here

Make sure there are no errors is your Manifest file.
If you delete the resource string app_name in /res/values/strings.xml, it doesn't know how to generate R.java right.
I found this a problem when doing the HelloSpinner tutorial.

I found that an unwanted resource was causing an issue. As soon as I deleted the resource R.java was generated.

I've had this problem, to rebuild R.java I cut the code in the xml file I've just been working on (or try others if this doesn't work), deleting the file then creating another with the same name and pasting the code back into it. Hope this helps.

Something that can be good to know is that if an XML file contains a ?, then R.java is not regenerated and the error is not shown in the XML file (sometimes it shows up after a while)
I you have a line similar to:
< string name="questionmark"\>?< /string> <br>
try to change the ? to something else and see what happens to the R.java file - worked for me

I had a similar problem, I had renamed a .wav file in the Raw folder with a capital letter. When I changed to all lower case, cleaned the project and it rebuilt R.java fine.

As others stated, stay away from creating your own R.java file. I ran into the same problem when I first started with Android, and it took some time to figure out what caused by compilation errors.
What were you trying to do with the R.java file?

I had the same problem. I just went to:
Project -> Properties -> Android
and chose the right Emulator for my project, I had 3 different to choose from in that moment. I realized that i changed the Emulator in some given moment. So try to change the Emulator, that might help!
Good luck

I had the same issue with IntelliJ. The problem was that I had app_name defined twice in strings.xml For some reason, IDEA inspections didn't pick this up automatically.

I read this on another site and it helped me:
"If that doesn't fix your problem, try modifying your AndroidManifest.xml (just add a space and save). I've heard that will force the R.java to rebuild. "
So just add a space in the manifest file and then rebuild!

As a side note, usually those *.out.xml files are generated by trying to build your project whilst an xml file is focused in the editor

I had similar problem.Cleaning project didn't solve the issue and there was no error in the code or the uppercase or spaces in file names.
The solution was going to a popup window which came when you choose PROJECT-->CLEAN and then UNcheck the "Start a build immediately" option. Clean the project. Close and reopen Eclipse and then build the project (PROJECT-->BUILD).
The question remains why simple clean and build without closing Eclipse didn't worked.

Android - How to regenerate R class? [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Developing for Android in Eclipse: R.java not generating
I have imported a project into my Eclipse IDE, but it's giving me an error since R file is not generated automatically.
How can I edit the R file so that it matches my project requirements?

In another stackoverflow question, somebody answered this : you must get rid of warnings and errors (syntax and links) in your xml files. This plus doing a clean / build project.
Project -> Clean, and choose the option to build the project.

I found this happening to me with a broken layout and everything blows up. Relax, it's like that old mistake when you first learned programming where you forget one semicolon and it generates a hundred errors. Many panic, press all the buttons, and makes things worse.
Solution
Make sure that anything the R. links to is not broken. If it's broken, ADK may not regenerate R. Fix all errors in your XML files.
If you somehow hit something and created import android.R in your activity, remove it.
Run Project -> Clean. This will delete and regenerate R and BuildConfig.
Make sure Project -> Build Automatically is ticked.
Wait a few seconds for the errors to disappear.
If it doesn't work, delete everything inside the /gen/ folder
If it still doesn't work, try right-clicking your project -> Android Tools -> Fix Project Properties.
What to do if R doesn't regenerate
This usually happens when you have a broken xml file.
Check errors inside your XML files, mainly within the /res/ folder
Common places are /layout/ and /values/ especially if you've changed one of them recently
Check AndroidManifest.xml, I find that often I change a string, and forget to change the string name from AndroidManifest.xml.
If you can't find the issue. right click /gen/ -> Restore from local history... -> tick R.java -> click Restore. This doesn't solve the problem, but it will clear out the extra errors to make the problem easier to find.
I know there's already a lot of answers here, but this is the first link on Google, so I'm compiling all the advice here and hope it helps someone else new to this :)

Ok, I fixed it:
When I changed manifest to target 1.5 version, million errors appeared and only one wasn't related to inexistance of R class - in manifest file attributes "targetSdkVersion" and "maxSdkVersion" did not exist in sdk 1.5
Because of this R class was not able to generate.

I had a similar problem where the R.java file was not being regenerated after I'd added some icons and layout files. I tried cleaning and rebuilding and things got worse since then the original R.java file was gone and still wasn't regenerated. Eventually it dawned on me that there must be compiler errors for the compiler that generates R.java and we aren't being shown those in the console. Fortunately, I had noticed earlier that
it's an error if one .xml file refers to another which is non-existent and
it's an error to have upper case letters in your file names (why is that forbidden, I LOVE camel case).
Anyways, after renaming my icons and .xml files to all lowercase and then fixing all the references inside the .xml files, voila, R.java was regenerated. Just in time to feel good when I stopped for lunch :-)

To generate the R file again:
Modify something in layout->activity_main.xml
Save the file
Project->Clean...
Just delete the R file located in gen directory, and then try Project->Clean.
Then build your app again.

You can also right click on the project -> Android Tools -> Fix Project Properties. That should cause the R.java class to be re-generated.

I reopen eclipse, edit one of my xml files and then discover that my activy class was refering android.R instead of my package "R" :-)

My problem was in Manifiest file.
I have deleted launcher icons and did not reference the new ones on Manifiest :)

In order to regenerate the R.class, you will have to try multiple techniques.
Remove any R imports from your java source files: import R.android
Make sure to open the "Problems" panel by going to Window->Show view->Problems
If you do have some errors in your xml resources, you will need to correct those errors. In my case I had to change my id attributes to include the "+" sign as follows: android:id="#+id/grp_txt"
Now proceed to do Project->Clean
Finally do Project->Close, Project->Open
The "+" sign indicates a new resource id and the forces the aapt tool to create a new resource integer in the R.java class.

If you use Intellij IDEA you can click Build - Rebuild Project

If you accidently deleted your R in eclipse by "project clean" (don´t do this)
Rightclick on your Projectfile -> Restore from local History...
recreate your R
My Case:
Broken xml caused bug in R. (because of ä, ö, ü, letters in id)
clean project deleted my R.
What I Did:
recreated R from local History
checked for wrong R imports in my classes (like import android.R) and removed them
fixed that xml file and saved its content in an external txt file
deleted the xml completely from my project.
ran my project one time
put that fixed xml back at its place
and...
gave my girlfriend a big hug without a reason after freaking out like a Hulk.

My problem was errors in my XML files. Errors aren't always automatically detected in the Android Common XML Editor or Android Common Manifest Editor, so try using the regular text editor instead. For example, somehow some random gibberish from a .java file had been inserted into my manifest and strings.xml files.
Right click on any XML files (most likely in the /res folder or AndroidManifest.xml) and click "Open With," then select "Text editor." Make sure everything looks good and then save. Also, make sure to enable "Build Automatically" for your project. I had deleted my R.java file and it was rebuilt from scratch, so no need to restore it from local history.

Try to add a new "Android XML file" to, for example, the /res/layout folder. This might cause the plugin to to regenerate the R class.

You can just modify any xml files in /res folder and even just add a space and save, it will be regenerated.

I had the same problem - "R" missing. And none of the advices given here helped. Fortunately, I've found the reason - somehow Eclipse got lost the Project-Properties-target. It was unset. I don't know till now, what had done it, but setting it back helped.
So, attention - missing R can mean the missing target, too!

I have tried all the solutions above. But they unfortunately it did not solve my problem.
My R.java was gone as soon as I pasted a new picture to my drawable folder.
After reading the answers for this question I tried to delete the icon I have previously pasted (while Build Automatically Enabled) and everything was fine afetr. Hope this will help someone!

I had that problem and I just right-clicked on packet of my project and Build Project. Instantly the class R appeared in packet gen.

In case someone else finds this thread when Googling, like I did:
I had what appeared to be the same problem for a while, and after some digging I noticed that the R.java file got correctly built, but was ignored for only one of my source files. The problem for this particular file was that Eclipse had "helpfully" added the following line at the top:
import android.R;
That effectively hides the project R stuff. Just remove it and everything will be fine again...

You can use Eclipse's "Restore from local history" to restore your old R file if it has been deleted. After that you possibly see what keeps Eclipse from building your files (I've seen other errors than before which really helped fixing the problem).

May be you can go to project properties and select Android option and then define the target for the project. Once you apply the selected target API for this project, it will automatically generate R.java.

Mostly a problem with an invalid layout file.
Open the 'Problems' view and look for erros in XML layout files. Fix them and the R class will be recreated.
In my case there wasn't a real error. The problem view showed an error in a xml layout. The editor showed the xml error too. Just reformatting the xml using the auto formatter with 'ctrl-f' 'fixed' the xml 'error' and the R class was recreated.

You can just delete the R.java file from your project and it will regenerate assuming you have build automatically enabled. If you do not have build automatically enabled simply goto project->build all

For me, it was a String value Resource not being defined … after I added it by hand to Strings.xml, the R class was automagically regenerated!

This problem normally happens when importing from an existing project. Try to fix all errors from all .xml files in res folder, as well as Manifest file. Most likely the errors are shown at "match_parent" parameter, change it to "fill_parent". When all errors are clear, R.java will be appeared.
If there is no error on any .xml file. Try edit any xml file (like delete a letter and type it back) and then save the file, this will cause to generate the R.java.

I have a problem that the findViewById(R.id.edit_text) but return a TextView not a EditText. I think the problem is the R.id class has wrong id number, then, i clean the project then its works fine.

In my case it was an improperly named XML file that caused my R file not to rebuild. This did not show up in the package explorer, but it was shown in the LogCat. Look out for any warnings there about your res files. No matter how many times you clean your project, the R file will not rebuild until those errors are taken care of.