Android - R cannot be resolved to a variable [duplicate]

Question

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R cannot be resolved - Android error

I am having a issue which I have had before and I don't understand the cause. My project and code is fine as it was running yesterday. I have open Eclipse today and the whole project looks like it contains errors.

I believe it is some sort of build path issue. I don't understand why it randomly occurs? But in the code where there is R.Layout.LayoutName there is an issue... can anyone help?

I have tried cleaning and building it, I have tried importing android.R but I didn't have this before, it then gives and error and says the layout file doesn't exist.

Claustrophobia

I have got two projects in eclipse, one is running fine and the other one isnt? – Claustrophobia

Kindly check the following link #885509 – Snowflake

this happens to me whenever I clean my project, it can stop me for days. there seems to be a dozens of different answers to this question involving changing settings deep in the project, which usually don't work and can cause other issues as well. – Alexanderalexandr

Answer 1

Are you targeting the android.R or the one in your own project?

Are you sure your own R.java file is generated? Mistakes in your xml views could cause the R.java not to be generated. Go through your view files and make sure all the xml is right!

Commodious

How do i check if the r.java class is being created? – Claustrophobia

Look if your_package.R.java exists in your project after building. – Commodious

Also i believe the xmls are correct as the application has been working fine for weeks and now all of a sudden it is not – Claustrophobia

No It is not there...why is this? – Claustrophobia

Are you sure nothing at all has changed in the project? – Commodious

not at all, i was working on it yesterday and it was running, came back today and its not – Claustrophobia

hmmm that is curious. Anyway, when I had such a problem once, I later realized my problem was in the xml files. Not necessarily a syntactic error which eclipse would detect, but a semantic one. Well, YMMV. – Commodious

I'm not sure why this is the selected answer - since it does not give a solution. – Hileman

@Hileman Mistakes in your files can prevent R.java from being generated. In that case, R will not resolve because it does not exist. – Commodious

normally your answer is right. if something wrong with xml, R is not generated. but in this case, the problem is yesterday was working, but today not working with all projects. all projects make error is not kinda xml problem i think – Moonfish

How to find WHERE in one of my xml files the error is? In Eclipse it is impossible! – Guggenheim

In my case the launch icon was not generated. After copy/paste default icon it was fixed. – Shevlo

Answer 2

I think I found another solution to this question.

Go to Project > Properties > Java Build Path > tab [Order and Export] > Tick Android Version Checkbox Then if your workspace does not build automatically…

Properties again > Build Project

Kileykilgore

This guy needs some votes. After half an hour of going through StackOverflow, this is the answer that worked for me and will probably work for many other people. Eclipse probably unchecks these automatically. – Swee

Totally agree with @AndrewLatham – Lavellelaven

Seriousy, this answer should be the accepted one. Either that, or make this a community wiki. – Amadus

Wow, this also worked for me. Eclipse and adt seem to conspire often to make the most subtle and absurd of errors. I don't know how reason alone could solve this one - thanks for your tip! – Reinold

I agree with @AntonI.Sipos. I have no idea why this a) happens or b) fixes the issue but it does. Ensure you tick the target SDK verion AND the Android Dependencies. Previously I have removed and reimported the source into the workspace to fix the issue. It seems a 'clean' will trigger it. – Cessation

After checking version go to Project > Clean or Project > Build – Uranium

I tried this too, but the problem persists. There seems to be more factors to this problem I'm afraid. Really nice answer though, with pictures and all! – Clubman

My android was unchecked. But, this did not solve the problem for me. Even after removing duplicate tags in my gui xmls and string xmls, the problem persists. – Brazil

This worked, but only after installing the Build Tools (Window/Android SDK Manager) – Thackeray

Does not work for me. "Build Project" is grayed out. – Bligh

my layout's graphical view is visible now...so i upvoted, but its still showing that "R cannot be resolved to a variable android" i.e. my java file is not generating. – Marginal

Answer 3

I've fixed the problem in my case very easy:
go to Build- Path->Configure Build Path->Order and Export and ensure that <project name>/gen folder is above <project name>/src
After fixing the order the error disappears.

Achaean

This worked for me. I have no idea how it ever would've changed, i've been working on the same project for 2 years and all the sudden this issue appeared. Ugh, eclipse and Android are so frustrating sometimes! – Brood

This was the case for me, but it did not end up fixing the problem. – Ballet

Same here, I swapped them and same error. – Joselynjoseph

The order was messed up for me. But, your answer also did not work for me. Do you know the reason why it causes an error ? – Brazil

Swapped them, but no change. – Bligh

it didnt worked for me :( – Marginal

Answer 4

You want Clean Project Like this

click on

Projects>Clean>select your project

this will help to u

Almeria

Clean step helped identify xml issues – Millett

Answer 5

check your R directory ...sometimes if a file name is not all lower case and has special characters you can get this error. Im using eclipse and it only accepts file names a-z0-9_.

Hullabaloo

I had just created a new xml file and I had used an uppercase letter. Woops! – Lessielessing

I had a double extension for a file (e.g. image.png.old). 10x! – Always

This worked for me. Voted up. – Whippet

Yep, I had an image with uppercase (ButtonTouch.png). Gotta rename all those images I'm copying over from the iOS version. :-) – Tarnation

Answer 6

Fought the same problem for about an hour. I finally realized that I was referencing some image files in an xml file that I did not yet have in my R.drawable folder. As soon as I copied the files into the folder, the problem went away. You need to make sure you have all the necessary files present.

Bullring

This worked for me. It's unobvious from the long list of errors that some of them are actually causing all the others. – Witten

Answer 7

Agree it is probably due to a problem in resources that is preventing build of R.Java in gen. In my case a cut n paste had given a duplicate app name in string. Sort the fault, delete gen directory and clean.

Sonatina

Delete the gen [Generated Java files]>Clean the project>Rebuild worked for me – Presentationism

Answer 8

Save all layouts, and replace them from the previous version. Start to copy one by one and clean the project everytime, sometimes one of the layouts has something, that eclipse doesn't like. It worked for me.

Sherburn