Related
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/.
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.
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.
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.
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.
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
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.
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".
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.
Close all files, clean project, restart Eclipse.
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.
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;
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.
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
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\\._].
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.
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.
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.
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.
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.
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.
You may need to update SDK tools. Relaunch Android SDK Manager again and install a new item: Android SDK Build-tools.
Try to make your new XML layout file name lower case. For example, use my_file.xml instead of myFile.xml.
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.
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.
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.
Just go to Android Top menu list. click on Build Menu, in under Build click on Rebuild Project.
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.
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>
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
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.
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/.
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.
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.
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.
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.
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
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.
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".
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.
Close all files, clean project, restart Eclipse.
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.
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;
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.
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
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\\._].
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.
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.
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.
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.
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.
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.
You may need to update SDK tools. Relaunch Android SDK Manager again and install a new item: Android SDK Build-tools.
Try to make your new XML layout file name lower case. For example, use my_file.xml instead of myFile.xml.
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.
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.
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.
Just go to Android Top menu list. click on Build Menu, in under Build click on Rebuild Project.
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.
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>
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
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.
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/.
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.
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.
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.
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.
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
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.
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".
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.
Close all files, clean project, restart Eclipse.
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.
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;
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.
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
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\\._].
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.
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.
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.
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.
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.
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.
You may need to update SDK tools. Relaunch Android SDK Manager again and install a new item: Android SDK Build-tools.
Try to make your new XML layout file name lower case. For example, use my_file.xml instead of myFile.xml.
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.
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.
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.
Just go to Android Top menu list. click on Build Menu, in under Build click on Rebuild Project.
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.
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>
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
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.
This question already has answers here:
Developing for Android in Eclipse: R.java not regenerating
(64 answers)
Closed 9 years ago.
In Eclipse, I've created a project from a source and now it shows errors - "R cannot be resolved to a variable". From what I found here, I had cleared and rebuilt the project, but still the R file doesn't appear in the /gen folder.
Any ideas?
Dont worry. First you may clean the project, then run the project. If this does not work then follow the following links:
Here is the best way to solve this problem: [Android Development- Where is my R.Java file?][2]
R.java not regenerating
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
If Clean/Rebuild Project doesn't work try to check our package name in AndroidManifest.xml.
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.
For me the error got fixed by making some changes in Android SDK Manager.
Whatever be the latest API level available, install its "SDK Platform". For me latest API level available was 16, so I installed its's SDK Platform as shown in the image below. It works fine now.
Cheers, Mayank
Did you just update both sdk and adt(from 21 to 22), then you need to install a new item: Android SDK Build-tools
Refer to:
Eclipse giving error, missing R.java file after recent update
For me somehow the Project properties; Android; Project Build Target was not set. I chose a Android version there (e.g. 4.2) and it fixed it.
for me, the best solution to suggest to people that have problems with the "R" file would be to try the next steps (order doesn't matter) :
update ADT & SDK , Eclipse and Java.
remove gen folder , and create it again .
do a clean-project.
right click the project and choose android-tools -> fix-project-properties .
right click the project and choose properties -> java-build-path -> order-and-export. make sure the order is :
Android 4.3 (always the latest version)
Android private libraries
android dependencies
your library project/s if needed
yourAppProject/gen
yourAppProject/src
make sure all files in the res folder's subfolders have names that are ok : only lowercase letters, digits and underscore ("_") .
always make sure the targetSdk is pointed to the latest API (currently 18) , and set it in the project.properties file
For me, there was a missing slash at the end of my SDK. In Eclipse > Preferences > Android > SDK Location
For example, change
/home/matt/android-sdk-linux
to
/home/matt/android-sdk-linux/
your android manifest must start with correct package
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="HERE - Correct package NAME"
android:versionCode="1"
android:versionName="1.0" >`
I got similar problem and solution I found out was in resources any of
the file aka background, sound etc must not contain capital letters or
any special symbol other than _
What you really need to do it just install "build-tools" from sdk manager,
and r.java will be generated automatically.
I had the same error. Error was that, I had placed a file in res/raw folder with invalid filename.
As soon as I corrected the file name to a valid one, error was resolved!
Allowed characters for naming a file:-
1. a-z
2. . _
3. 0-9
4. no capital letters
Capital letters were the issue in my case!
Sometimes you can accidentially add an import to "R", so if at the top of your code you see some weird import about that that you did not add yourself, delete the reference, and everything should go back to normal
My problem was strange and took some time to find. Somehow the package of the src file changed so that the last entry in the package was deleted. So for example initially my class MyActivity.java was in package com.abc.client.test.app but after I added a user permission, the app got removed and the package was renamed to com.abc.client.test. I don't know how it happened. Renaming the package and putting the java file in the correct place fixed the problem.
I found this problem when trying to run the Notepadv3 programme from Googles 'first lesson'..
For me it was an issue with the xml file, due to the API level I was using. I renamed each case of Match_Parent to the older type of Fill_Parent. Oh and if you have already auto-built the project then you need to delete 'import android.R' on NoteEdit.java and Notepadv3.java, clean the project (click 'Project', then 'clean...') before saving.
Solved it for me. Came from this post Android NDK r4 san-angeles problem
Can't believe Google dosen't warn of this problem - I have been setting up another PC to start programming again and even with a bit of prior knowledge this was a pain.. How do you set the API when importing an existing project??? Can't see where there is any dialogue option when you 'File' 'Import' etc ..
Scamparelli
Check the androidmanifest.xml file and layoutfolder xml files. They should be created properly as the starting and ending clause in xml should be placed properly. Update the files, clean and build. And all set!
I had this problem and none of the other guides helped, and then I realized I didn't have the java jdk installed on my system. If you haven't done this either go download the version corresponding to the version of eclipse you installed (x86 or x64)
It is possible you have an error in your *.xml files: layouts and etc.
Try to modify AndroidManifest file.
For example add space and delete this space. After this OPERATION, save project. Resources will be refreshed. It can help.
I solved the problem with resolving R resource on fc19.x86_64 and ADT v22.0.5-757759 by installing additional libraries after Fedora and ADT upgrade.
yum install ld-linux.so.2
yum install libstdc++.so.6
yum install libz.so.1
Those libraries are required by adb (Android Debug Bridge version 1.0.31).
Then restart Eclipse and perform project clean Project->Clean check project you would like to clean.
Hope it helps :)
Project > Clean...
usually regenerates R.java file located in gen/com.mypackage
In my case, R.java wasn't getting generated because of a hierarchical parent error, which in turn was cured by updated one or more Eclipse plugins (Go Eclipse-->Help-->Check for Updates)
I got this error when I added a js file to the res folder.
An error indicator was set on the res folder icon. In all the classes where I used R I got this error.
I moved the js file to the assets folder and everything worked.
Problem was eclipse was not generating R.java.
To resolve this issue please go to project->clean... and select your project and select ok and then clean and build project and import your package name R file(Ex com.demo.R). It works.
This can happen when the android naming convention isn't followed. Check if you have placed a file/photo into one of the android folders and make sure that the file name contains only lower case letters
I know this is an old question but I just solved my own version of it and perhaps this might help someone.
After two days of tearing my hair out with this, I finally got around it by deleting the raw folder, then recreating it and dropping the file(s) back in.
After that, another Project > Clean and it at last compiled.
I got this when I renamed a project. Although the project is renamed, some references are not. Clearing lint, and then rerunning lint helped. (Right click project > Android Tools > Clear Lint Markers, then Run Lint)
My setup was broken after a recent update where the SDK build tools need to be installed separately after the SDK installation. So build tools update + Eclipse restart fixed this for me.
Credit goes to the Android reply here
When other solutions fail, select your project and delete it. MAKE SURE YOU DO NOT REMOVE FILES FROM DISK.
Then use file>import>existing android code into workspace, and select the location of your project.
I been having this and i did trace it back to the layout files.. It happend to me again however i could not find noting in the layout files. I looked in the string.xml and there was it.. one of the string names started with cap and that was causing the problem.
Fix any XML formatting errors in the XML Files in your /res/menu folder.
Might be a compile time error from the XML file being improperly formatted.
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/.
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.
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.
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.
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.
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
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.
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".
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.
Close all files, clean project, restart Eclipse.
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.
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;
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.
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
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\\._].
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.
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.
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.
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.
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.
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.
You may need to update SDK tools. Relaunch Android SDK Manager again and install a new item: Android SDK Build-tools.
Try to make your new XML layout file name lower case. For example, use my_file.xml instead of myFile.xml.
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.
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.
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.
Just go to Android Top menu list. click on Build Menu, in under Build click on Rebuild Project.
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.
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>
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
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.