This question already has answers here:
"R cannot be resolved to a variable"? [duplicate]
(30 answers)
Closed 9 years ago.
I am getting this classic error in Eclipse IDE. I am bored of Eclipse's bugs. They driving me mad.
I almost tried everything which suggested as solution (by Googling). None of them worked.
My project was working normally but not code changes.
I see that my code changes does not acting on my app (on AVD) then I cleaned my project (under Project > Clean...). R.java file was gone and res folder was empty.
Now I am getting that error: R cannot be resolved to a variable.
What should I do?
And also I tried to delete project and create again with Android Project from Existing Code I've backed-up before. It already gives same error after cleaning.
Any ideas would be appreciated.
I assume you have updated ADT with version 22 and R.java file is not getting generated.
If this is the case, then here is the solution:
Hope you know Android studio has gradle building tool. Same as in eclipse they have given new component in the Tools folder called Android SDK Build-tools that needs to be installed. Open the Android SDK Manager, select the newly added build tools, install it, restart the SDK Manager after the update.
I'm not posting this as an answer but a confirmation to Paresh's accepted answer. I recently updated SDK tools to Revision 22 and I noticed my code changes was not being affective on the device i'm testing at all. Such as the url I was using, I was getting errors for connection time out regarding the url I was "previously" using. Therefore I cleaned the project and built again only to find out that autogenerated R.java file is missing.
After reading Paresh's answer and checking what's going on with my sdk manager this is what I saw:
SDK Build-tools 17 was not installed and there was already a new update to SDK tools even though it does not mention any change related to this problem in the changelog, this update brought back my R.java file and the related problems were gone after an eclipse restart and final clean/rebuild on the project.
The R file can't be generated if your layout contains errors. If your res folder is empty, then it's safe to assume that there's no res/layout folder with any layouts in it, but your activity is probably calling setContentView and not finding anything -- that qualifies as a problem with your layout.
Try to delete the import line import com.your.package.name.app.R, then, any resource calls such as mView= (View) mView.findViewById(R.id.resource_name); will highlight the 'R' with an error, a 'Quick fix' will prompt you to import R, and there will be at least two options:
android.R
your.package.name.R
Select the R corresponding to your package name, and you should be good to go. Hope that helps.
In addition to install the build tools and restart the update manager I also had to restart Eclipse to make this work.
I had a fully working project to which I was doing a minor change when this occured after updateting the SDK.
Eclipse updated the SDK and the ADT but I could still not build the project. Exlipse said there were no further updates available.
The problem persisted until I manually uninstalled the ADT from eclipse and re-installed it.
Only then would my project build. I had restarted eclipse inbetween each step.
Related
This question already has answers here:
"R cannot be resolved to a variable"? [duplicate]
(30 answers)
Closed 9 years ago.
I am getting this classic error in Eclipse IDE. I am bored of Eclipse's bugs. They driving me mad.
I almost tried everything which suggested as solution (by Googling). None of them worked.
My project was working normally but not code changes.
I see that my code changes does not acting on my app (on AVD) then I cleaned my project (under Project > Clean...). R.java file was gone and res folder was empty.
Now I am getting that error: R cannot be resolved to a variable.
What should I do?
And also I tried to delete project and create again with Android Project from Existing Code I've backed-up before. It already gives same error after cleaning.
Any ideas would be appreciated.
I assume you have updated ADT with version 22 and R.java file is not getting generated.
If this is the case, then here is the solution:
Hope you know Android studio has gradle building tool. Same as in eclipse they have given new component in the Tools folder called Android SDK Build-tools that needs to be installed. Open the Android SDK Manager, select the newly added build tools, install it, restart the SDK Manager after the update.
I'm not posting this as an answer but a confirmation to Paresh's accepted answer. I recently updated SDK tools to Revision 22 and I noticed my code changes was not being affective on the device i'm testing at all. Such as the url I was using, I was getting errors for connection time out regarding the url I was "previously" using. Therefore I cleaned the project and built again only to find out that autogenerated R.java file is missing.
After reading Paresh's answer and checking what's going on with my sdk manager this is what I saw:
SDK Build-tools 17 was not installed and there was already a new update to SDK tools even though it does not mention any change related to this problem in the changelog, this update brought back my R.java file and the related problems were gone after an eclipse restart and final clean/rebuild on the project.
The R file can't be generated if your layout contains errors. If your res folder is empty, then it's safe to assume that there's no res/layout folder with any layouts in it, but your activity is probably calling setContentView and not finding anything -- that qualifies as a problem with your layout.
Try to delete the import line import com.your.package.name.app.R, then, any resource calls such as mView= (View) mView.findViewById(R.id.resource_name); will highlight the 'R' with an error, a 'Quick fix' will prompt you to import R, and there will be at least two options:
android.R
your.package.name.R
Select the R corresponding to your package name, and you should be good to go. Hope that helps.
In addition to install the build tools and restart the update manager I also had to restart Eclipse to make this work.
I had a fully working project to which I was doing a minor change when this occured after updateting the SDK.
Eclipse updated the SDK and the ADT but I could still not build the project. Exlipse said there were no further updates available.
The problem persisted until I manually uninstalled the ADT from eclipse and re-installed it.
Only then would my project build. I had restarted eclipse inbetween each step.
I am using ADT bundle for my Android Application Development
1) From last two days whenever I open my ADT bundle its showing error in all the projects (But I have no errors in my projects and I am sure about it). I tried to clean all the projects but no use... Sometime a restarting eclipse will solve this problem but after few days I am getting this same errors again.
2) Also In my Android SDK Manager some packages like Google API and system images in extras were broken, I don't know what to do.
I tried to clean my projects and to update the SDK manager but nothing solved my problem. Kindly tell a better solution to solve this problem. And tell me why these kind of errors are happening.
Thanks a lot in advance.
But for this kind of problems need more clarifications. Here is my few tips to resolve it. It may or may not work! But better give a try.
In each class or java file which place exactly it showing the error? For example for few it will sow error in R. file and the error will be R cannot be resolved into type. If you are getting this error try to import you package R. file (Like import com.example.R) will resolve issue. If you couldn't import then try to check the package name in manifest file and other layout files. Try to resolve all errors one by one in res folder then clean will help it.
Next check whether Eclipse issue or ADT issue. You said few things are broken in ADT i don't know what exactly it means but try to uninstall and re-install them again.
Try to update eclipse. You can do it by Help->Check for updates
If nothing helps follow the error which are displayed in Problems tab which present near console tab. Otherwise open it here Windows->Show View -> Problems.
Hope anyone will help you if not please follow the errors and edit your question with error. So you might get better answers!
I had the same trouble.
I completely remove Eclipse and SDK bundle; then, i re-install everything.
This worked for me.
Do check this, Lint Error Checking will slow your ADT also seems to be occur error like what you got in a often situation..
so Disable lint from Windows-> Preferences -> Android-> Lint Error Checking, Under
Uncheck the two option in right hand side.
Be aware of what all your projects have JDK compliance.. set common JDK level.. mostly 1.6 based on need change to 1.7 for all projects..
set JDk compliance level in properties of your project -> java compiler and select in right hand side..
Always Check when importing any projects after import if its came up with a compatibility library or external library to be added like appcompat_v7
Check in properties of project under android tab in library section if there is any missing files..
From all the above suggestions are not fulfilled your problem, then go ahead with a new fresh latest ADT Bundle with a fresh download of platforms of SDK.. it will solve most of the ADT problems..
Finally the problem solved
This problem occurred due to missing target SDK in project properties and because of the broken files in SDK manager.
What I did is:
1) I deleted all the broken images and Google api packages from the SDK manager and I re installed all the packages again,
2) Then I selected android 4.2 as the Android Build Target in the project properties.
Thanks all for the time and help.
The title says most, but I have created a new project in Eclipse. I have everything set up, and as soon as I create a new Android Application Project, once everything has Generated there are 2 Errors: both "R cannot be resolved to a Variable", on Line 19 and Line 12. In the Video Tutorial Series I am watching it says there should be a file called R.java in the gen folder, but there isn't, just an empty folder. The Android project is completely new. Here are some of the things I have tried after googling, none solved the Issue:
Clean Project
Uncheck/Re-Check Build Automatically
Build Project
Close/Open Project
Check XML files for Errors - only the Two Errors as mentioned above in the Error Log
add "import android.R.*"
Create R file manually (Add -> Class)
It is my first time writing an app in eclipse, I know there are a lot of questions like this but none seem to solve my problem. The Java Errors (R not resolved to a variable) Errors are the only errors, no errors in the XML or Anything.
So that you can check my project, I have put it in my Dropbox if you want to have a look at it in eclipse.
Project Download Link
You can create the new Project and then copy the contents of this project into the new one.
This problem is with Eclipse. I recommend you to use Android Studio.
What might help, would be to create a new project and transfer the current project to that one. When the R file is not created when creating a new project, try and re-download the development tools and sdk.
I'm sure that the problem may be with your ADT tools in eclipse. Sometimes, this errors may occur due to some installation mistakes or some sort of software cracking problems. I also faced the same problem at my starting stage. The best thing that you can do is to move on with re-installation of ADT in you eclipse. It may help you. Try this!! Create you new Android Project and Enjoy buddy !!
I was having this exact problem, and found the solution after much headache.
In eclipse, find and click the button labelled Android SDK Manager (next to save, and all that jazz on the toolbar).
In the manager, make sure that under the "Tools" folder all of the relevant "Android SDK Build-tools" have been installed. Once they are, restart eclipse, and your R.java file should be generated. Hope that helps!
Although I know this question has been asked a million times, I have tried going through many of the stackoverflow questions and none of the answers have worked.
I have an old version of my project that I know worked and built correctly, which I added back into my eclipse workspace. When I clean and build the project, I am given with errors with the R cannot be resolved..
What I've tried:
- Building/Cleaning project
- Was going to clear the gen folder, BUT R.java didn't even exist in there
- Checking through my XML files to ensure there's no errors
- Restarting Eclipse
Extra note:
- My ADT plugin and Android SDK was the LAST version directly after Google released it's updates to merge everything over to Android Studio.
I just solved this problem for myself. I was using the Eclipse Android SDK on Windows 7. The problem was that the Eclipse program did not have permission to create the R file. To fix it I went to "User Account Control" settings in the Windows Control panel and lowered the slider to a lower security level. After rebooting the computer and cleaning the application in Eclipse Android SDK there were no more errors.
I've experienced the same problem a week ago. After installing the beta version of android studio I was unable to run android projects in eclipse. Uninstalling android studio fixed all the "R cannot be resolved to.." errors.
After trying everything I tried one last thing.. which was to update all of my plugins and libraries for Android. This actually solved the issue. I'm sure not that many people will probably have my specific issue since it will eventually go away, but it is a different problem I have not found and a different solution I have also not found...
I faced Simmilar problem, i cleaned project, Restarted Eclipse, and many other things like remove errors from problems,
but it was DUE TO: an Image Name in Drawable it contained Capital Latter i did Re factor -->Rename and Problem solved..
I am a newbie to android programming .I was doing tutorial from Commsware tutorial , to be precise T3 tutorial during which I cleaned the project.After that R class file has stopped generating.
I deleted that project,looks like the same error is getting propagated to other new projects I am creating.
This error is coming for the newly created project also.
I tried all the solutions in stackoverflow like : cleaning project,selecting android version in build path , deleting my workspace,freshly install eclipse etc..
The other intimidating thing is my res folder does not show any errors and my xml file does not contain any capital letters.
It must be some silly error which is causing this?
Perhaps you should take a look at this if you've recently updated SDK tools.
After updating to SDK Tools to rev. 22 for the first time, you may need to relaunch Android SDK Manager again and install a new item: Android SDK Build-tools.
After installing this, clean your projects and rebuild.
this happened to me after updating the android dev kit and esclipse.
couple of things you should try.
if you updated ADT, you must restart ADB server. you probably haven't read the message that says after update. or maybe restart whole pc.
if you're using external jar files, rename the libs folder to lib and revert it back to libs (from eclipse, f2)
There seems to be a problem with the target build settings within your projects.
The R file will not be autogenerated if there is the slightest error in your project. E.g if you use elements in a layout xml file that are available only in Android 2.2 but your project targets android 2.0. Sometimes the offending elements don't show up as errors because, syntax-wise, they are correct.
I advice you look at your target builds in android manifest.
Or target a higher android build (Get the latest one via SDK manager)