Develop Reference

R.Java error - Android Developer Studio -Eclipse-

I have a nasty problem with R.Java in Eclipse, when trying to add new images to a newly created folder on my Res (drawable). what could be the problem ? Nothing happens after cleaning the project...

Maybe you are using non-compliant names for your resources (like file with uppercase letters).
Please read the Android naming conventions.

Make sure the image you copy have all letters in the filename as smallcase . This could be one issue. File name: must contain only [a-z0-9_.]

I had faced many times same problem.
try the below steps. it could help you.
In Eclipse
1. Enable Problems view by clicking,
Windows->ShowView->Problems
check the problem and solve.
2. Remove R.java from gen folder of your eclipse try to build it again.
3. Check for Import R in your project. sometime eclipse imports android.R instead of yourclassname.R
4. Check for your XML file where sometimes id will not generate if you add it manually in xml file.
5. Reopen the project.
Hope it helps.

R.java was modified manually! Reverting to generated version

I added one xml file in layout. After that this error is coming. But the problem is I haven't touched R.java file.
Now in my new activity i m going to set its content view as my newly created xml file, but when i m doing R.layout., the newly created xml is not coming in suggestion. Do anybody have any idea how to correct this.
I have cleaned my project several times but it is not working.

Delete R.java and let eclipse regenerate it, then project --> clean will fix it.

Check if you have any existing errors in your code, if yes correct it and then try refreshing and building your Project.If your Project is properly build,you will get the new xml file in suggestion

It happened to one of my Eclipse projects today. This is what fixed it mysteriously. Don't know why or how.
Changed Properties->Android->Project Build Target to a higher (different) version of Android and hit the Apply button. Then did a clean build. The problem went away.
After the above steps, I could even go back to the original Project Build Target without the problem re-appearing.

May this Help you...
I think your xml file name might be having some capital letters or some special characters..
Delete them and then try again to run the project..

Try cleaning the project this will do the work.

make sure your not importing any thing that ends with com.R
make sure your naming convention of the layout is correct

R.java file have all the resources IDs provided to resources(drawables, layouts, styles etc) either by Programmer, or generated through sdk. So check your xml files as well as your drawable folders. If any of them including wrong format it will show an error in R.java file like sometime R.java is not generating or our class file shows R.id.xxx is not found or R.class is not defined error.Then clean your project.

There must be some mistake in one of your xml files. Eclipse does not always show error messages if there is something wrong with your xml. Mostly code gets errors, in this case 'R', so you will need to go through your xml manually, it could just be a simple mistake. Good luck

I had similar problem. Cleaning project didn't solve the issue and there was no error in the code or the uppercase or spaces in file names.
The solution was going to a popup window which came when you choose PROJECT-->CLEAN and then UNcheck the "Start a build immediately" option. Clean the project. Close and reopen Eclipse and then build the project (PROJECT-->BUILD).
The question remains why simple clean and build without closing Eclipse didn't worked.

Right Click on Project->Bulid Path->Configure Build Path
ther you see error android-support-v4.jar remove this library and add library again this works fine for me.
Else
Try
Go to gen Folder delete R.java and from Project option choose Clean Project.

Very late on the scene...
I had this line mysteriously appear at the start of my imports:
import android.R;
I deleted it and shazam error was gone.

I had similar error, but when I import new project to my eclipse. and the solution was, I should check the option (copy project to work space) specially when our project has library.

Not getting R.java file

I am not able to get back my R.java file after cleaning my project.
Please suggest me a solution which help me in this matter..
thanks in advance...

this can happen from one of two reasons:
you are not auto-rebuilding your project. (can be fixed in the settings).
you have a property within your project with and illegal name (such as files with capital letters).
fix this and the project will rebuild with no problems.

Try building your project by selecting your project--> Build Project.
remove the Build Automatically setting from your projects tab of eclipse.
Try building them manually.

The eclipse is not able to build R.java . There might be some problem in your xml layouts. Check them out.

R.java disappeared

I recently downloaded the Android Support Package and have been using it trying to get my application, running at SDK 10, to use a GridLayout.
Anyway, I cleaned my project a few times working on this error in my XML files, and then when I went back to my classes in /src, every single reference to R.* was an error.
This has happened to me before, but it usually fixes itself, and it has not yet. Does anyone know what to do?
The R.java file is no longer in my /gen folder.

It sometimes happens when you import another project First i suggest you to build it, it will create automatically .
If it's not working then try to create new project from existing source and specify the downloaded project . It worked for me
Hope this works for you let me know..

Sometimes if there is an error in your XML files R.java won't build. Go through your XML files to make sure that everything is in order (typo, forgetting to close a bracket, etc). When you fix that it should build itself again.

You can also try Adnroid Tools>Fix Project. That may help you to create gen/R.java file

Follow following steps :
In Eclipse,
=> Right Click on Project > Android Tools > Fix Project
By this way, you can fix many common problems which can help generate R.java in gen/R.java file.

There can be several reasons why this occurs. The following I have found happen to me and I have included the steps I took to resolve them.
First step is to try and clean the project (from the Project menu option I believe)
Check there are no errors with your XML files. Sometimes this is obvious from the red 'x' that appears next to an XML filename in the Project exlporer window and sometimes it is not. If it is not obvious check the 'Errors' window (whic is founf in the 'Windows' Menu option
Failing that I have found that by disabling the automatic build option, adding some arbitrary comment to an arbitrary source file, saving the source file, clean the project, remove the comment and then re-selcting automatic build can work too.
Apologies for the approximate locations for some of the Eclipse functions but I am not currently in front of Eclipse to check.

This happens when you have an error in the res folder.
Fix the error first, then do :
Project --> Clean --> Ok
Et voila !

How to generate R.java

I downloaded few source codes from Google source codes.
I executed them on Eclipse but R.java file is not created and therefore I got many errors saying that R cannot be resolved. There is no main.xml in layout too. Some other XML files are there. How can I execute these programs?

As long as you have a valid Android project, you can use aapt package to generate the R.java from resources. Here's example usage (all should be in one line):
aapt package --non-constant-id -f -m -M <abs_path_to_AndroidManifest.xml>
-S <abs_path_to_res_dir> -I <abs_path_to_platforms_android.jar>
-J <abs_path_to_dir_that_should_contain_gen_R_java)
--generate-dependencies
The above can be made scriptable using ANT by using the aapt target or by simply using an exec target.

Presume you have Android sdk. If you have.. just clean the project. R.java will be autogenerated.

Hi I just faced the same problem. The file R.java is deleted an regenerated each time you clean the project. In my case there were some errors in one of .xml files and no R.java was generated. If you did not have Main.xml that might be the reason. anyway if you fix .xml problems R.java should be generated.

Open Android SDK Manager
Tick Tools that there are 3 packages of Android SDK Tools , delete and install them again.
When they are finished, please refresh your project in Package Explorer.
You will see BuildConfig.java and R.java in /gen
I think you wanna need that I recommend this comment
Enjoy with your building app.

After few hours frustration finally I have decide to remove the red marks from the my file where it was not able to resolve the R.java as it was not actually available in my code. After removing the first red line from my activity file the project builds and generated the R.java automatically.
This is something really freaking thing for me as it goes without any reason and came back with the same thing.

If your build.xml includes the "-resource-src" target (which it will if you include $SDK_DIR/tools/main_rules.xml or lib_rules.xml) you can rebuild it with ant.

For future readers, restart adb then clean.

Correct all errors in the Xml layouts, if the errors is only in the id attribute, change to other name an save, then type the original values, this solution works for me.

I encountered this issue after adding a jpg file with a numeric file name into my drawable folder. I was getting a compilation error, " expected on line y" when trying to rebuild the project after cleaning it. You may want to check that you do not have a similar issue. Although I encountered this while using Android Studio, I am sure it would affect Eclipse as well.

Cleaning the project, delete the R.java and regenerate it.
If you have an error anywhere in your /res file (the resources) , the R will not be generated usually.
It could be an error in the name of a picture , or anything ...
fix your errors before.
good luck ;)

I have encountered similar problem and i changed the workspace folder and all errors disappeared. It's sort of simple solution but it works.