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.
every time I try to use something from my resources like a layout file
R.id.frameTwo
R cannot be found and android studio automatically puts android. before the R so it does not find any of my resources and I have errors all over the place.
the error is Cannot resolve symbol R
Why cant my resources be found?
You should import com.yourpackage.application.R.
If R.java isn't being properly generated, the problem is in your XML files. Figure out what's going wrong there.
Check that your package is correct at the top. Sometimes Android Studio does weird things.
It could be:
package com.yourpackage.applicationname
Also check if there is an import statement with R in it. If there is remove it as it's not needed.
I was having a project open in Android studio. It was generated by the wizard and working fine.
I did some small changes to activity_main.xml and when I changed back to MainActivity.java i get the error in several places that it cannot resolve R. I might have done something to cause this. But I´m not sure what since it appered when I edited the xml.
Does anyone know what might be the solution to this?
I can find the R.java in r/release/packege/com/ and it looks fine.
Most of the time it is due to a bad XML file. XML files can be layout files, value files, or the Manifest file. Please check your xml files and try to rebuild the project. Sometimes cleaning the project and rebuilding it also works.
In addition, make sure you do not have a drawable with an invalid name. I had a drawable with a numeric filename and that didn't sit well with Android so it failed to compile R.java.
Downgrade Your Gradle Plugin Version
No amount of cleaning, rebuilding and restarting would do the trick for me.
The only thing that did the trick was downgrade our Gradle version from 3.4.0-alpha02 to 3.2.1.
So, instead of:
dependencies {
classpath 'com.android.tools.build:gradle:3.4.0-alpha02'
}
We used:
dependencies {
classpath 'com.android.tools.build:gradle:3.2.1'
}
After making that change and then doing a Gradle sync, everything worked.
Not sure if it's related to the alpha release or to that version or if changing your Gradle version at all just forces a refresh that otherwise cannot be done with the other commands, but there ya go.
Make sure in your AndroidManifest.xml the package name is correct. That fixed the problem for me when my R.whatever was marked red!
Try to clean the project by doing the following:
If you are using Windows, open CMD, cd to your project directory and run gradlew clean.
I just had this problem and the reason was that after editing the layout android studio automatically added an import to the source files:
import android.R
Of course the main R class has not all the symbols in your layouts, which made everything a red mess.
Removing that line solved for me.
EDIT:
Seems like eclipse had the same problem early on.
I sometimes get this after updating Android Studio. Not always straight away but after a while (perhaps after a restart of the program).
Here is what has worked for me: Tools - Android - Sync project with Gradle files.
For some reason just clicking the "Sync now" link that shows up after changing the build.gradle file has not done any change for me. Even though the messages says approximately the same thing.
I had the same problem because in my strings.xml I forgot to escape a apostrophe. Use " \' " never " ' " in xml file!
I had that same problem crop up, too (most recently while I was at lunch--came back and WTF?). And since this was a simple Hello, World program, there wasn't many places these errors could hide. The XML files looked fine--I hadn't even touched the manifest. A clean did nothing.
So I commented out a section of my layout.xml to try to narrow down the problem. Sure enough, the errors went away.
And then I simply UNcommented out exactly what I had commented...and everything was hunky-dory. Strange! Perhaps there was some lingering issues that needed to be touched in order to cause a rebuild of the layout file. You'd think basic stuff like that wouldn't happen these days, but they do.
One more thing! It's possible that something may happen to Java as well. It's very hard to know the status of the Java run-time environment; just easier to start again. So here's one more thing to try: restart your computer, restart Android Studio, AND THEN Invalidate Caches and Restart. Yep, the whole-hog.
When all else fails restarting android sometimes helps. During the start files are loaded afresh and this enables detection of the R
This problem occurs when you rename the package name.
After renaming the package name, you must change the older package
name to a newer one.
For me it solved the problem once I changed that.
After that, you might get errors in xml files, that you have to change
the package name there also.
That's it.
I just had the R problem and after a few hours found that the problem was my regional spelling as used in one of my xml files. The problem word was behaviour, which is spelled behavior by Americans.
I am Australian and we are taught ye olde English way of spelling certain words and so I looked past it a number of times before the penny dropped.
Its a small thing, but it can easily sneak up and bite you on the nether regions and is hard to spot and can waste a lot of time.
In my case I had just added some new image files to the drawable folder and accidentally put a GIF in there with my PNGs. I had not incorporated them into the project at all yet. I removed the GIF and then did a clean and rebuild. That fixed it for me.
I had this exact problem when importing a Udacity Example Program. The Message Pane in Android Studio said the error was failing to load a .PNG in a sub-directory deep in the Project Files.
Turns out the PNG with all of the sub-directory path names was greater than the name length limit defined by Windows 7 (260 characters). I gave the Project a shorter name - to free up some space - and then Android Studio happily compiled.
After you tried make project, clean project, rebuild project but still doesn't work.
Try restart Android studio
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.
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).