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R.java file missing or "R cannot be resolved to a variable"

Tell me the possible solution for R.java file missing or "R cannot be resolved to a variable"
I have tried the following still R cannot be resolved as a variable error is coming.These are the following things i have tried:
Make sure that anything the R. links to is not broken. Fix all errors in your XML files. If anything in the ADKs are broken, R will not regenerate.
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. If not, build it manually via Menu -> Project -> Build Project .
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.
Check your *.properties files (in the root folder of your app folder) and make sure that the links in there are not broken.
Right-click your project > properties > Android.
Look at the Project Build Target and Library sections on the right side of the page. Your Build Target should match the target in your AndroidManifest.xml. So if it's set to target 17 in AndroidManifest, make sure that the Target Name is Android 4.2. If your Library has an X under the reference, remove and re-add the library until there's a green tick. This might happen if you've moved a few files and folders around.
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.
Check that Android SDK Build-tools is installed. Window->Android SDK Manager->Tools->Android SDK Build-tools
Make sure when you update the Android SDK Tools, you also update the Android SDK Platform-tools and Android ASK Build-tools. Build fails silently if they don't match.
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 believe you give the effort but only the problem is XML Error in your layout file.You give a wrong id or something like that.Because this also happened with me and finally i found the error in my xml file and when i fix that error and pressing CTRL and Key S.Eclipse builds the R file..!
I also suggest you to get the R file from project backup and again give a try.

always check your res folder first, if there is an error there, the build will fail, resulting to no generation of the gen files

There is some error in your Xml code.
What you have to do is find it and correct it. it may be any error like hwight and width not specified for some view.
once You have done it your R.jaav will be created just fine.
if still not so clean Your Project and recompile will do the Trick.

Error when importing an existing project to eclipse

So I'm trying to import an existing project to eclipse and when I do I get the following error. The main folder of the project in the package explorer has a red exclamation mark (!) next to it and console says the same error 3 times:
[2013-07-10 14:23:39 - Myproject1] Project has no target set. Edit the project properties to set one.
[2013-07-10 14:23:39 - Myproject1] Project has no target set. Edit the project properties to set one.
[2013-07-10 14:23:39 - Myproject1] Project has no target set. Edit the project properties to set one.
I did my research on this error and found a bunch of stuff on this website already but nothing helps. People are mostly getting this error when they try to execute the imported project, not as soon as they import it. I also tried setting the "target set" in the project properties, as the error tells me to, but I can't find where to set the "target set" anywhere in the properties.
One more thing worth mentioning also, if I open the src folder and try to open any of the *.java, everything is blank, the "code" opens but it's blank. Any help would be greatly appreciated!

The file 'project.properties' is missing. It must reside in the root-folder of your project.
( Where the AndroidManifest.xml is located )
You should create a new android-project and import the sources and resources
OR create it manually.
Example content for project.properties:
# Project target.
target=android-17
Greetings
Christopher

set android target version on your project manifest xml file or eclipse ->right click project click properties->select android tab->check latest android version on the list like below screen shot:
after click ok button will apply wait some seconds after your issue will be solved!

you should try fixing project properties:
rightClick on Project -> Android Tools -> Fix Project Properties.
That resolved my issue!

You are probably importing your project folder on your workspace. In my case, i got that same error, so i just move the project folder to "C:" and tryed to import again. And bingo!

Java/Eclipse - No more R file ever

I'm on Eclipse for hours now and I didn't found a solution yet for my problem even after many searches on internet: I have no more R.java file on my projects.
On just created or on my old projects, i don't have R file anymore and I tried so many solutions (uninstall, re-install Eclipse, clean my project, check all my XMLs, fix problem with android tool and so on ...)
Please someone can tell me what to do in this case?

Hey If you just updated to ADT Rev 22 :
I had the problem too. There is a new component in the Tools folder called "Android SDK Build-tools" that needs to be installed.
Step 1
Open the Android SDK Manager
Step 2
Select the newly added Build Tools and install. (If problem stays then go to Project Properties => Java Build Path => Order and Export and check Android Private Libraries, then clean and build project.
It may be necessary to repeat the process, restart the SDK Manager after the update and make sure it looks like this (all tools installed):
More info:https://groups.google.com/forum/?fromgroups=#!topic/android-developers/rCaeT3qckoE%5B1-25-false%5D

Perhaps in Project Properties -> Java Build Path -> Libraries you don't have:
Android 4.2.2 (or other version)
Android Dependencies ?
If so, then right click project - > Android tools -> fix android properties
and see if this library showed up.

Thank you all for saving me! I've spent the whole afternoon on search this error.
Finally, my project works.
By the way, I also encountered one problem which i wanna share with you:
After upgrading, even if my project has not errors anymore. During runtime, it seems it couldn't find the classes from the jars placed in \libs.
Go into Project=>properties => Java build path= > Order and Export.
Please make sure all your jars are checked.

If this problem occurs suddenly in a well working project,
the first step is to find whether the problem occurs only in the current project or in all other projects.
if all other projects in the current workspace are working then 90% problem is with XML / mainfestfile/resourse file that you edited recently.
This error is not shown as red mark we have to find out what we have done recently in these files.

try this
sudo apt-get install lib32stdc++6 lib32z1 lib32z1-dev
it solved my problem

Close your eclipse and after refreshing system, try to open Eclipse again. I think you are using Emulator along with the eclipse. It may be because of the low Memory problem (RAM) of your system. I used to face the same problem when I use Emulator

whenever there is any mistakes in any of the xmls the R goes missing when a build or clean happens so check for any xml errors in your project unless you fix it you cant get back your R on clean or build. fix the xml files and perform a clean you will have the R generated. Also check in File->properties->Builders and see if everything is checked

I was using Eclipse Indigo and nothing I tried worked. I ended up downloading Juno SR2, reinstalling the ADT, and now everything works again.

Reinstall everything and it'll work.. i.e. go back to Google SDK or w.e. you're using and download it.
Update it to latest in SDK Manager.
Go into Eclipse-Project-Prefs-Java build path-order/export TICK EVERYTHING.

problem: No R file get generated.
guess: Try cleaning project if it is old one. Else create new project with no R get generated and with no compile errors but this: no project.apk
In this case you have to check your SDK for the built-tools. May not be installed after updating SDK.
Thus download them if not download here, then put them under directory: SDK/built-tools folder. Lastly, and most important, is to Run the SDK As Administrator. This guarantees refreshing SDK with all packages appearing in it.
Install the SDK-Built-Tools or any missing packages according to the above link and you're done.
hope this helps.

Try one thing, create a new Android Project and transfer all those files which are in the previous project. That worked for me.

In my case there is error due to "&" inside strings.xml file(but error not shown) for declaring string for a array type. Now the problem has been solved as I changed "&" to "and".
So, please make sure that you do not have such silly use of symbols, and clean the project.

I have had the same kind of problem, however Rechecking all XML files in the Resources folder was helpful in my case. I found syntax error in my XML files. Cleaning and building the project again can be helpful sometimes too.

I had the dreaded not more R.java.
Some of the things I've used in the past:
Clean / rebuild (the first thing we all try)
Restart eclipse (optionally reboot pc/mac)
Update both SDK/ADT eclipse plugin to latest version
Create new eclipse workspace and import project
Enable Verbose AAPT build output Eclipse menu>Preferences>Android>Build
Port project to Android Studio / Gradle (this helped my actually see the AAPT error i was getting Error Code:138)
Delete recent XML changes - Ultimately I found deleting recent menu.xml files I'd added and commenting out where they were referenced fixed the issue and I finally got R.java.

I got the error recently and had found no fault in any layout or value file. After a lot of tries I add another Activity and the R.java was build and the error disappeared. I don't know why this occur, but it takes me hours.

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.