i am editing mainactivity.java code file this error occur
R cannot be resolved to a variable
when i import R then their further more new error occurs like
bAdd cannot be resolved or is not a field
bSub cannot be resolved or is not a field
tvDisplay cannot be resolved or is not a field
kindly guide me how can i remove these errors
Project -> Clean : do it a few times until you see the errors go away.
Select "Build Automatically" so that every time you clean the project, it will be rebuilt. And yeah, make sure you are saving the file before cleaning it (I know it is weird but sometimes the errors refuse to go away until you save it and then Clean it). Make sure that there is no error in the files in the layout folder, as it sometimes prevents the auto-generation of the code in R.java
Also, make sure that your code in MainActivity.java does not have import android.R. Eclipse tends to add that when you are managing the imports.
R is a generated source that recreated while building the project. Make sure that the project is built (in eclipse, there is an option for auto build in project->build automaticcaly).
Do not import R. This is not the R you looking for.
The error causes due to your any of XML file contains error.So check all xml files and clean the project and build it.
I need help badly. I tried to to a clean in my android app Project>Clean. After doing this, All my classes started to have errors. It can't detect the R in --> findViewById(R.id.heightVal); And it cannot locate some other files, xml ids and xmls. Any ideas?
I think you import android.R in your activity . If it is the case then delete that line and clean project again.
R is an automatically generated class that holds the constants used to
identify your resources. If you don't have an R.java file (it would be
gen/eu.mauriziopz.gps/R.java in Eclipse with the 1.5 SDK) I would
recommend closing and reopening your project or going to Project >
Build all (and selecting "Build Automatically"). If that doesn't work than try making a new
project.
this might help you if you are using Ganymede and in some other versions of eclipse had experienced similar problems either restarting or doing this cleared it most of the times
right click on your project then click configure build path tick the android file shown there
Try to comment all the lines in XML file that show an error.
Clean up the project.You can uncomment the lines if R.java has been regenerated.
If the id's are still not detecting try closing and reopening the project.Its weird but sometimes you have to do it.
I have just been working on my android project in eclipse and all of a sudden this error appeared, my manifest file matches the name of my application etc.............!
What I have noticed is that that the auto generated Java files are missing from the gen folder its completely empty now.
orginally I had to create a default.properties file as there wasn't one present and it was working fine uptil the point i tried to add a button into one of my xml files. Tried to clean project too and that hasn't resolved the issue either.
Any ideas?
This error is usually caused because you have an error in one of your resources. Check to make sure that there are no errors in the xml resource files or the drawable directories. In the list of errors you are seeing you should look at the top most error and see if you can resolve this. What tends to happen is that an error in one of your resource files is causing the generation of the R file to fail. Once the R file fails to generate you will see a huge list of errors but they are all caused by the one error.
Remove the gen folder from Project Name ->Properties -> Java Build Path ->Source. You will get an error message after removing it. Now Add the gen folder again in the same way. You can now see the R class. If the problem remain, then try to remove both src and gen; add them again.
use "Project" -> "Clean" in Eclipse to re-generate your R file and fix other android issues.
...sometimes this helps a lot! ;D
Help, I'm occasionally encountered this randomly with Android, but this time seems pervasive and I want to know how to fix this once and for all - in this situation
I cleaned my project because I added a new ID and reference in the XML and a new drawable asset, yet the project was giving an error on the ID reference (so this is why I cleaned it).
Now the R file isn't recognized, and it doesn't regenerate when I clean the project, or close the project, or close/open eclipse
R cannot be resolved to variable, now I can't compile, le sigh
solutions and pinpoint the cause of this problem?
Had to check the console for this one. It had an issue with an image named "default.png"
apparently you can't use default.png for drawable names.
that combined with R file won't compile if you have XML errors (saw that answer in another stack exchange, so it helped me look for things)
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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.