Develop Reference

R cannot be resolved issues in my android project

I already cleaned the project , and set the automatic build after clean it up
but there are 50 errors regarding the 'R cannot be resolved to a variable'
how to fix this issues ? i really confused ...
Thanks before

This error is usually caused by either of these possibilities:
The most probable: You have a syntax error in any of your layout files (i.e., the files located under the res\layout folder of your project). The bad thing of this is that Eclipse won't warn you and tell you what's the error, so you'll have to go one by one looking for the syntax (probably an unmatched tag, an unmatched attribute, etc.) and fix the issue.
The other possibility is a syntax error within your AndroidManifest.xml file. Same goes here, check it for syntax errors.
One of these two will fix your issue.

I've had problems like that before, while importing a project to my workspace, I don't know if that's your case, but this answer helped me in those cases:
Android Eclipse - moving project caused all R reference errors

android doesn't recognise Resources folder after cleaning the project

Hi I had some errors on my project and tried to clean it but after that now all of my files do not recognise anything that it has to do with the Resources folder. What can I do ? I have more than 20 files with errors now. Please help. Any advice would me much appreciated. Thanks.

An error in one of your resource files will cause R to not get built. That in turn will cause an error in your Java code everywhere a reference to it is made. You may or may not see the error reported in the "Problems" and/or the "Console" windows.

R cannot resolved to a variable in android

I know this question is asked many times. But still that answers are not resolved my problem. My code shows an error "R cannot resolved to a variable in android". I cleaned and build automatically many times and also fix the project properties but the error still same. How can I resolve this error ?? please help me and thanks

look for the errors in res folder and resolve it first.
It can be an error in layout, drawable, values etc..

Check the last layout, drawable, values etc where you made changes prior to getting errors. You must have made an error there. It usually is using captial letters or - in drawables or import to "R" in your activity or some problems in xml like name match_parent to Match_parent etc. Here are some links with similar problems
Android Development- Where is my R.Java file?
R cannot be resolved - Android error
R cannot be resolved to a variable
R cannot be resolved to a variable -- mailing list entry
Fixed: R cannot be resolved to a variable

Try one of these.
1>Could be a problem in your xml
2>right click on the project->Android tools->Fix Project Properties (check if the build target is checked)
3>SDK update (Build tools would have not been downloaded) go to android sdk manager and download tools (to find out create a new project if it cannot resolve R then go ahead with this step.)
Hope this helps

Try to remove "import android.R ;" at the top of your code.

R cannot be resolved-android

R cannot be resolved
R.layout.main cannot be resolved
error is repeating to me and i cant run any of my android program
pls give any instruction

also probably delete this line which sometimes creeps up :
import android.R or something like that.

Are you using Eclipse?
Try project -> clean
Otherwise: check your console in the bottom for errors that need fixing before your R is build

I just had a reoccurence of the dreaded "R cannot be resolved" error, and I went through all the usual fixes; make sure all resources have lower case names, do a clean, make sure there isn't an import android.R lurking somewhere... no luck.
After a couple of frustrating hours I realised I had saved a PaintShop Pro format file (something.psp) in a resource folder in the file system and Eclipse was pulling it into my res folder. Not being a .png, it choked, and that seemed to cause the problem. As soon as I removed the .psp the error disappeared.
Hope this helps prevent someone else pulling out their hair.

R.java malfunctioning

I created a new xml file, and had an errant ? in it that prevented R.java from regenerating. I tried Cleaning the Project, and Fixing the Project Properties but no luck.
Then I realized the XML was creating the R.java from recreating itself, so I deleted the XML file and the R.java was back.
Now though, I am getting an error on all the calls to R.. calls saying that :
cannot be resolved or is not a field
So, for instance I have
setContentView(R.layout.detectlayout);
ERROR: detectlayout cannot be resolved or is not a field
for all of my calls to 'R.'. Any ideas?
I have tried all of the suggestions on SO already to no luck =/

Look at the 'import' section of your code. Since you deleted your original R, chances is Eclipse help you to fill in the R as com.android.R instead of com.yourproject.R
I also sometimes have problem in Eclipse Resource stuff, sometimes I found turning off and on the "auto buiild" function may help, or simply restarting Eclipse may sometimes help. It's kind of buggy under Mac OS.

This can happen if .R is imported. Eclipse will automatically add it sometimes when you have difficulty with with R.java

first don't bother deleting the R file it not going to make things better only worst lol
as you said you some times need to clean the project
when you start modifying resources its good to select the root of your project and do a alt+shift+o to reload all ressources
then f5 to refresh the tree
then clean the project
you also have to check that eclipse is set to build automatically (Project->build automatically).