R cannot be resolved - Android error

Question

I just downloaded and installed the new Android SDK. I wanted to create a simple application to test drive it.

The wizard created this code:

package eu.mauriziopz.gps; import android.app.Activity; import android.os.Bundle; public class ggps extends Activity { /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); } }

but Eclipse gives me the error

R cannot be resolved

on line

setContentView(R.layout.main);

Why?

PS: I do have an XML file named main.xml under res/layout/.

For those who still experience some problem with eclipse not being able to update/generate R.java. A possible solution is by creating a dummy xml and just delete that xml. In my case this is the solution — denil, CommentedJun 25, 2012 at 10:59
Honestly, this sounds so stupid (and it is), but modifying the AndroidManifest.xml, then undoing that edit, then saving the file worked for me. If I cleaned the project after that, it broke again. And all this time I thought Xcode was the only IDE that had these kinds of mysterious errors. — iwasrobbed, CommentedDec 22, 2012 at 18:12
Did you try right click on the project -> Android Tools -> Fix Project Settings? — Serg Kryvonos, CommentedFeb 1, 2014 at 10:59
Please check your XMl layout file, if any error in xml you can't generate R.java, and the error comes after bulid and clean also. — swiftBoy, CommentedFeb 20, 2014 at 11:47
Just a tip: when I switched IDE from Eclipse to Android Studio this stopped happening to me. — mata, CommentedJul 17, 2014 at 12:13

4 revs, 2 users 82% · Accepted Answer · 2012-08-13 17:58:22Z

After tracking down this problem as well, I found this note in the Android documentation:

http://source.android.com/source/using-eclipse.html

*Note: Eclipse sometimes likes to add an "import android.R" statement at the top of your files that use resources, especially when you ask Eclipse to sort or otherwise manage imports. This will cause your make to break. Look out for these erroneous import statements and delete them.*

While going through the Android sample tutorials, I would often use the Ctrl + Shift + O command to "Organize Imports" and generate any missing import statements. Sometimes this would generate the incorrect import statement which would hide the R.java class that is automatically generated when you build.

This happens as well, but a bunged up layout file can also cause it. — GHz, CommentedMay 20, 2012 at 2:40
This classic bug has been in Eclipse for YEARS and never gets fixed. 1000s of people face this same problem. — Carol, CommentedJun 15, 2012 at 5:58
Eclipse developers, please remove this $£%&"$&/ bug! Google developers, please give me a £$&$"%& Android suite similar to Xcode for the iPhone! — Abramodj, CommentedOct 28, 2012 at 18:30
@2-Stroker : It is a bug. It happened to me when I created a branch new andorid project via the eclipse WIZARD and it complained about 'R cannot be resolved'. I had to comment out the setContentView & getMenuInflater lines and then eclipse generated the R.java after which I could uncomment setContentView & getMenuInflator. Abramodj is right, the environment has serious problem if even your 'hello world' example does not compile. Fix it google! — CF_Maintainer, CommentedMar 17, 2013 at 17:28
How does Google not grant eclipse.org funds to get items like this fixed? — Cris, CommentedJun 30, 2013 at 23:32

2 revs, 2 users 50% · Accepted Answer · 2012-03-13 00:31:43Z

397

Each time I had a problem with R not been generated, or even disappeared, this was due to some problem in the XML layout file that prevented the application from being built.

edited Mar 13, 2012 at 0:31

community wiki

2 revs, 2 users 50%
Luc

21
+1 for this. I had an older styles.xml file with parent="android:WindowTitleBackground" and it was breaking my build and preventing anything generated to "gen". The error wasn't actually reported except in the Console window right when I first opened the project.
– Scott Persinger
CommentedMar 8, 2012 at 0:56
12
exactly, if you copied layouts from another project, and are getting this, looks for missing drawables - that will fix it instantly!
– Gabor
CommentedMay 22, 2012 at 11:45
4
I thinh I have the same problem, is there any way to know witch one of the layouts?
– Sergey Kucher
CommentedOct 13, 2012 at 8:57
3
Yes, I was missing a drawable file and that prevented the R file from even being generated. The weird thing is that I had a android:icon="@drawable/XXX" declaration on an <item> in a menu resource, but there was no red squiggle signalling that the drawable resource XXX wasn't found. In other instances, "@drawable/YYY"was flagged when YYY was not found, but not in this case. For some reason.
– taylor
CommentedApr 12, 2013 at 18:08
5
Yes, excellent solve. When one gets this error.. many times all of the layout files are marked as having errors.. This is because they are all looking for R. One of them however, likely has an error unrelated that aborts the build. In my case, a missing drawable.
– Todd Painton
CommentedApr 18, 2013 at 19:46

| Show 5 more comments

5 revs, 5 users 40% · Accepted Answer · 2022-12-22 10:12:30Z

Whenever you get

R cannot be resolved

then check for the /res directory and there must be some file that have some error in it and that is preventing the application from being built. For example, it may be a layout file or it may be due to some missing resource is, but you already defined it in the XML file.

If you have any additional, even unused (!) or unreferenced (!) images in a folder like res/drawables-mdpi which do not comply to the file naming conventions (may contain only [a-z0-9_.]), the R.java class might not generate, causing the chain of events all the other posts referred to.

I had this problem with the sample ApiDemos. Some missing resource in the strings.xml file. XML error are listed in the Eclipse's console. — lemotdit, CommentedJul 31, 2010 at 3:34
thank you! this was my issue, i had a layout that was erroring out but there was no message about it. — george9170, CommentedNov 22, 2010 at 13:58
How can you check for errors? I get nothing in my console when building/running — Vincent, CommentedApr 11, 2011 at 9:33
How to find out WHICH xml file causes the error? Eclipse does not mark them! — Yar, CommentedApr 18, 2014 at 11:35
I had 2 images with same name in hdpi folder (1 with png and 1 with jpg format) deleting 1 of them resolved the issue — Haseeb Jadoon, CommentedNov 2, 2014 at 6:42

3 revs, 2 users 85% · Accepted Answer · 2012-09-12 21:23:46Z

140

my project have include a r.java.at the beginning ,R.layout.main work good.But,after adding some code it doesn't work,and the error is R.layout.main can't resolved.what's the problem?

Look at your imports. Chances are that the line:

import android.R;

will be there. If that's the case, remove it, so that your project will resolve R not with the default Android Resources class, but with the one auto-generated from your /res/ folder.

edited Sep 12, 2012 at 21:23

community wiki

3 revs, 2 users 85%
Dimitar Dimitrov

5
Thanks @Dimitar,that fixed my issue! Eclipse and the auto-import feature seem to have gotten me by adding that import line automatically.
– Steven
CommentedJun 8, 2010 at 3:12
7
I've also had similar issues when I named a layout using capital letters
– Travis
CommentedOct 24, 2010 at 20:46
This is one of the top 5 reasons people get "R not found". I've compiled a problem/solution page with images that show the main 5 at link below. Truly hope the list helps people since this is a common problem. spragucm.wordpress.com/2014/05/13/…
– Chris Sprague
CommentedMay 13, 2014 at 19:17
after removing R, at some places R is used as class & is giving error now, How to resolve that?
– Narendra Jaggi
CommentedMay 24, 2015 at 17:36
In my case, that line was added automatically when I pasted Java into a Kotlin file and let Android Studio do the automatic conversion.
– jamespgilbert
CommentedJun 7, 2024 at 16:48

Add a comment |

2 revs, 2 users 89% · Accepted Answer · 2013-07-04 20:40:15Z

97

And another thing which may cause this problem:

I installed the new ADT (v. 22). It stopped creating gen folder which includes R.java. The solution was to also install new Android SDK Build Tools from Android SDK Manager.

Solution found here

edited Jul 4, 2013 at 20:40

community wiki

2 revs, 2 users 89%
Michał K

Myself also. And when I selected the SDK manager, lo and behold, the build tools shows up auto-checked for installing, with a note that it wasn't installed! What gives???
– David at HotspotOffice
CommentedJun 3, 2013 at 20:46
I had the same issue. I'm so glad you shared this. I looked error from my own code two days. I'm very diappointed to Google, because this error message has been very difficult to solve, but it has been caused by own error, allthough tools dis not report properly what causes it. I has done same time changes to my project so I thinked it was my fault again.
– Reijo Korhonen
CommentedJun 23, 2013 at 10:51
5
Worked for me, thanks! It just reinforces my mantra: "never update anything while developing".
– Rodrigo Dias
CommentedJul 16, 2013 at 22:11
i was hanging around for looking for the answer but nothing worked for me. i think it was a eclipse or sdk problem. so as you are saying, i just delete prev eclipse bundle and reinstall it. and then it is working. your answer was helped
– beginners
CommentedJul 24, 2013 at 0:42
This was the problem in my case! Wasted one day trying to fix the R error, adding/removing references, and trying other options. Mine was a fresh new setup of ADT, and a new android project creation, and was still getting the error. It turned out finally, I had to install all available updates of Android SDK Tools, Android SDK Platform Tools and SDK Build Tools :p
– Saurabh Kumar
CommentedAug 4, 2013 at 3:19

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2 revs, 2 users 84% · Accepted Answer · 2012-03-13 00:30:07Z

What Will said was right

R is an automatically generated class that holds the constants used to identify your >resources. If you don't have an R.java file (it would be gen/eu.mauriziopz.gps/R.java in >Eclipse with the 1.5 SDK) I would recommend closing and reopening your project or going to >Project > Build all (and selecting "Build Automatically" while there as recommended by >Josef). If that doesn't work than try making a new project, if the problem is recreated than >post here again and we'll go into more detail.

but I've found out that there was another problem that was causing the first one. The tools in the SDK directory didn't have the permissions to be executed, so it was like the didn't exist for Eclipse, thus it didn't build the R.java file.

So modifying the permission and selecting "Build Automatically" solved the problem.

@Jignesh - cd $ANDROID_SDK_ROOT/build-tools/<version>. Then chmod a+x on files like aapt, aidl, dexdump, dx, etc. ANDROID_SDK_ROOT should be set in your environment, and it will point to your SDK installation. For example, /opt/android-sdk. Its important to set both ANDROID_SDK_ROOT and ANDROID_NDK_ROOT because the Android tools use them internally. See Recommended NDK Directory? on the NDK user's list. — jww, CommentedFeb 14, 2014 at 5:54
@Lewis.. I already select the "Build Automatically" but the error is still there. — d_unknown, CommentedApr 26, 2015 at 2:05

2 revs, 2 users 74% user286516 · Accepted Answer · 2012-03-13 00:38:02Z

R.java is a file that the Android Eclipse plugins creates while building your application. R.java is created under the "gen" directory. This file is generated from the information in the "res" directory. If you run select "Project" -> "Clean..." on the Eclipse menu, it will remove and then regenerate the R.java file.

The problem "R cannot be resolved" happens when you change your package name in the AndroidManifest.xml file. It uses your Android package name to create a subdirectory under the "gen" directory where it stores the R.java file.

Eclipse may have problems executing clean, because it is confused about where the R.java file is when you have changed the Android package name. You can either rename the subdirectory under gen to match your new package name, or you can change your package name back to the old name. Do the clean and then change the package name to the new name you want. This works best if you stop Eclipse from trying to build while you are changing the package name. Under the "Project" menu uncheck the option to "Build Automatically" and also when the "Clean..." dialog asks if it should "Start a build immediately" uncheck the box so it doesn't try to build while you are changing the package name. After you have changed the name you can turn "Build Automatically" back on again.

Note that if your AndroidManifest.xml file package name does not match your Java package name, Eclipse will end up automatically adding an "import <your Android package name>.R;" line in all your .java files that have any references to R. If you change your AndroidManifest.xml package name, sometimes Eclipse does not update all of these added imports. If that happens, use the Eclipse refactoring (ALT + Shift + R) to change the import statement in one of your Java files to your new AndroidManifest.xml package name. It is best to do this while you have disabled "Build Automatically".

Multiple Copy/Paste of files and name refactoring lead to the same issue, despite all file names and contents were Ok. Cleaning the project, deleting R.java manually and all the import headers, then rebuilding these import headers (still with CTRL+ SHIFT + O) worked fine. — hornetbzz, CommentedMay 18, 2012 at 23:07
This worked for me. I had changed the package name in the manifest. I had to use ctrl-shift-O in the classes that referenced the generated R class values in order to add the correct import. — Chuck Krutsinger, CommentedJul 5, 2012 at 17:07
This fixed it for me. Also have seen the import issue occur in the past, but this time the issue was the package name in the manifest was not matching the package name in the src folder. — Jim Range, CommentedApr 3, 2014 at 18:31
I had two activities in my application. One had a different package name to the one that R was generated against. I had to import R manually using something like import com.example.main.package.name.R; — Oliver Moran, CommentedMay 16, 2014 at 14:16

Will · Accepted Answer · 2009-05-20 01:46:29Z

R is an automatically generated class that holds the constants used to identify your resources. If you don't have an R.java file (it would be gen/eu.mauriziopz.gps/R.java in Eclipse with the 1.5 SDK) I would recommend closing and reopening your project or going to Project > Build all (and selecting "Build Automatically" while there as recommended by Josef). If that doesn't work than try making a new project, if the problem is recreated than post here again and we'll go into more detail.

This worked for me, but I had to "Project -> Clean..." first. — Matt Connolly, CommentedFeb 19, 2011 at 21:20

4 revs, 4 users 29% · Accepted Answer · 2013-03-01 12:35:33Z

29

Close all files, clean project, restart Eclipse.

edited Mar 1, 2013 at 12:35

community wiki

4 revs, 4 users 29%
sharika

23
+1 But sometimes it needs 3 eclipse restarts and 7 project cleans in between. Just keep trying ;-) #rant
– Matthias Bauch
CommentedDec 13, 2011 at 16:33
3
Mix it with touching (edit+save) .xml files (strings.xml ...).
– Ali Shakiba
CommentedSep 23, 2012 at 17:57

Add a comment |

3 revs, 3 users 64% · Accepted Answer · 2017-12-11 07:06:37Z

25

It is worth checking in AndroidManifest.xml. The attribute package has the correct value.

That is:

<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="your.correct.package.name" ...

After you change that, the R.java will be re-generated.

edited Dec 11, 2017 at 7:06

community wiki

3 revs, 3 users 64%
seven

My original package name was com.xxxxxdroid.router. I created a new version of my app com.xxxxxdroid2.router. Once I had done this I had to update the package name in AndroidManifest.xml, but only much later after I had started to copy and paste old classes across. Thanks for the pointer!
– Eugene van der Merwe
CommentedJan 28, 2012 at 23:41
this fixed my issue, I was working in an xml file, glad I remembered which one, I've got loads of them... thanks...
– GHz
CommentedMay 20, 2012 at 2:39

Add a comment |

2 revs, 2 users 77% · Accepted Answer · 2012-03-13 19:22:44Z

This error can also be caused by adding an activity to a namespace that is different to the root namespace for your package.

For example, if com.example.myapp is the root namespace for your package, you can then add an activity to the com.example.myapp.activities namespace.

This will produce the "R cannot be resolved" error.

To fix the import the R in the default namespace in your activity should be:

import com.example.myapp.R;

This helped me, I had moved my activities into a package below the root, adding the root package as an import (import com.example.myapp.R;) solved the problem. — eageranalyst, CommentedFeb 9, 2013 at 12:45

2 revs · Accepted Answer · 2014-08-25 06:51:53Z

Along with the great suggestions in the previous answers, make sure your Android target is set:

Right-click on your project
Choose Properties
Choose Android in the left menu
Tick a box next to the appropriate Project Build Target.
Click Apply and OK

Edit: A year later I found another cause. I had a .jpg image in my drawable folder with the same name as a .png image. Referencing this image in my code must have confused the program and it gave the "R cannot be resolved" error.

Sunil Kumar · Accepted Answer · 2013-08-29 07:09:04Z

Make sure you installed the Android build tool form sdk manager

project right click properties-> Java BuildPath select Library and add android-support.jar the follow these step.

Go to Project->Properties->Java Build Path than select Order and export tab. Set android-support .jar library checked and up it into top of the list. And clean and rebuild..It works for most of the cases

enter image description here

2 revs, 2 users 67% user132014 · Accepted Answer · 2012-03-13 00:48:44Z

I just had this problem for the millionth time and realized what was causing it: I created an XML file with uppercase letters in the name. All your XML filenames in /res must match [a-z0-9\\._].

also, i just noticed stack overflow requires us to escape all backslashes. — user132014, CommentedJul 1, 2010 at 2:52

3 revs · Accepted Answer · 2012-10-04 16:22:51Z

16

Simplest solution - Sometimes you just need to save the XML file you were working on to get the autogenerator to kick in.

Save the file (e.g. main.xml) then delete the R.java file and see if the regenerated R.java resolves the R resolve problem.

edited Oct 4, 2012 at 16:22

community wiki

3 revs
akim

True. Sometimes, if it says there is a problem in your XML where there isn't (red squiggly line or yellow exclamation point), delete the offending line, save the XML file, paste the line back in, and save it again. If you are not building automatically, build again after that, and it just might work. Eclipse is stupid sometimes. :)
– hotshot309
CommentedJan 21, 2012 at 4:58
Despite the other answers listed above, this one turned out to be the correct one for me. I initially got the "cannot find APK" message when I went to compile some sample code, then did a Clean which generated a ton of "R cannot be resolved" errors, and then just opening the .xml file and manually saving it the errors were cleared and I could compile.
– sXe
CommentedJun 1, 2012 at 2:15
So true: After cleaning the projects the R.java was gone - editing and saving the strings.xml solved the problem.
– BurninLeo
CommentedJun 16, 2012 at 5:34

Add a comment |

3 revs, 3 users 40% · Accepted Answer · 2012-07-05 11:32:58Z

Check the XML file names. Be sure that they're all in lowercase.

Also make sure that any image resource names are also all in LOWER CASE. I had a capital letter in the name of my jpg file, and it caused the R unresolved error right across my project.

+1 for this was my issue. You must name your images like so: eicon.png not eIcon.png. I found the error by looking at the Consol. It was returning an error on the file with Invalid File Name:... — jasonflaherty, CommentedNov 1, 2012 at 5:53

2 revs, 2 users 50% · Accepted Answer · 2012-08-13 16:53:10Z

R is a generated class. If you are using the Android Development Tools (ADT) it is generated whenever the project is built. You may have 'Build Automatically' turned off.

2 revs, 2 users 64% · Accepted Answer · 2014-01-21 01:17:50Z

This error cropped up on my x64 Linux Mint installation. It turned out that the result was a failure in the ADB binary, because the ia32-libs package was not installed. Simply running apt-get install ia32-libs and relaunching Eclipse fixed the error.

If your x64 distro does not have ia32-libs, you'll have to go Multiarch.

Check #4 and #5 on this post: http://crunchbang.org/forums/viewtopic.php?pid=277883#p277883

Hope this helps someone.

It's worth noting that if you have a 64-bit Linux installation you WILL need ia32-libs. If you don't have it, attempting to execute the adb command will result in a strange message saying it can't find the file or directory. — rs_atl, CommentedJun 21, 2012 at 18:52

Eddie Martinez · Accepted Answer · 2013-11-06 04:19:43Z

You may need to update SDK tools. Relaunch Android SDK Manager again and install a new item: Android SDK Build-tools.

enter image description here

Nazmul Hasan · Accepted Answer · 2016-04-02 01:36:28Z

You may need to update/install SDK tools. Relaunch Android SDK Manager again and install a new item: Android SDK Build-tools.one by one delete,fix which one work for you.

2 revs, 2 users 67% · Accepted Answer · 2012-08-13 16:53:59Z

I had this problem as well. It turned out that I had inadvertently deleted the "app_name" string resource from the strings.xml file, which was causing a silent error. Once I added it back, the R class was generated successfully and everything was back up and running.

2 revs, 2 users 50% · Accepted Answer · 2012-03-13 00:41:13Z

Try to make your new XML layout file name lower case. For example, use my_file.xml instead of myFile.xml.

+1 YES! Make sure it follows the correct naming conventions... [a-z0-9_.] — jasonflaherty, CommentedNov 1, 2012 at 5:54

2 revs, 2 users 67% · Accepted Answer · 2012-08-13 17:56:07Z

Yet another reason R.java might not get autogenerated is if you have directories like res/drawable-hdpi, res/drawable-mdpi, or res/drawable-ldpi.

1.6+ seems to be OK with these directories, but 1.5 doesn't want them. When I removed those directories, R.java started autogenerating for me again.

2 revs, 2 users 80% · Accepted Answer · 2012-03-13 00:46:51Z

Often times this is because of the MinSDK version number you supplied when creating the project. Example:

If you want 2.1 to be the minimum, Android 2.1 is actually API Level 7.

You can see what I am talking about when you browse the SDK you downloaded and installed. Navigate to the place you installed the SDK to (C:\android-sdk-windows for example) and open the folder named "platforms". You will see something like "android-7" listed as a folder, and if you open that there is a source.properties file that, when opened with a text editor, will show you the corresponding platform version.

When you create a project, and you must select a "Build Target" API, the last column in that list named "API Level" shows the number you are looking for when populating the MinSDK setting.

This is probably one of the most common mistakes that results in the R.java file not being created under Project > gen > packagename > R.java.

2 revs, 2 users 50% · Accepted Answer · 2012-03-13 00:49:34Z

Remove main.out.xml. I'm new to this and don't yet know what this file is used for, but removing it cleared the problem.

Gundu Bandgar · Accepted Answer · 2016-03-29 06:28:20Z

Just go to Android Top menu list. click on Build Menu, in under Build click on Rebuild Project.

Jaimin Prajapati · Accepted Answer · 2017-03-28 07:59:45Z

First check is there any error in any xml layout or not, if then resolve it first.

Otherwise remove junit dependency from project and rebuild the project.

3 revs, 3 users 73% · Accepted Answer · 2012-08-13 16:55:49Z

In case anyone is interested (I might be saving your life here), I had the error, R.xml cannot be resolved, slightly different on a GLS project. Hmmmm. After looking in R.java, I found an auto-generated class, XML.java, (I think) was not there.

Solution? It needed a new folder in res: res\xml and a file called default_values.xml in there. Then all was OK.

Just in case you have not got that file, it's:

<?xml version="1.0" encoding="utf-8"?> <PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"> </PreferenceScreen>

user350617 · Accepted Answer · 2010-06-14 15:13:09Z

So I have run into this problem multiple times when switching build targets. Usually doing a Project >> Clean worked for me. This last time, however, it did not. Finally I tried to open my default.properties file, located under the root project folder. I received an error message stating that it was out of sync with the file system. I actually deleted it and copied a coworkers version which allowed eclipse to rebuild my R file. I will paste what it looks like below. It is named 'default.properties'.

# This file is automatically generated by Android Tools. # Do not modify this file -- YOUR CHANGES WILL BE ERASED! # # This file must be checked in Version Control Systems. # # To customize properties used by the Ant build system use, # "build.properties", and override values to adapt the script to your # project structure. # Indicates whether an apk should be generated for each density. split.density=false # Project target. target=android-3

vkris · Accepted Answer · 2010-11-21 16:48:40Z

I had the examples of Android 8 and was trying to use Android 7 SDK. When I closed the project and reopened the application folder and chose to use Android 8 SDK, it was able to find the R file. Hope this helps.

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