I've found out that my R.java is never updated, so it doesn't contain information about my new resources, so I decided to delete it and thought that Eclipse would generate a new one. But that didn't happen, and I don't have R.java now. How can I regenerate one?
I'm using Windows 7.
From one of the comments: "Doing Project -> Clean is what caused the problem for me. Cleaning deletes R.java...and for whatever reason the plugin is not regenerating the file."
I found this happening to me with a broken layout and everything blows up. Relax, it's like that old mistake when you first learned programming C where you forget one semicolon and it generates a hundred errors. Many panic, press all the buttons, and makes things worse.
Solution
Make sure that anything the R. links to is not broken. Fix all errors in your XML files. If anything in the ADKs are broken, R will not regenerate.
If you somehow hit something and created import android.R in your activity, remove it.
Run Project -> Clean. This will delete and regenerate R and BuildConfig.
Make sure Project -> Build Automatically is ticked. If not, build it manually via Menu -> Project -> Build Project .
Wait a few seconds for the errors to disappear.
If it doesn't work, delete everything inside the /gen/ folder
If it still doesn't work, try right-clicking your project -> Android Tools -> Fix Project Properties.
Check your *.properties files (in the root folder of your app folder) and make sure that the links in there are not broken.
Right-click your project > properties > Android. Look at the Project Build Target and Library sections on the right side of the page. Your Build Target should match the target in your AndroidManifest.xml. So if it's set to target 17 in AndroidManifest, make sure that the Target Name is Android 4.2. If your Library has an X under the reference, remove and re-add the library until there's a green tick. This might happen if you've moved a few files and folders around.
What to do if R doesn't regenerate
This usually happens when you have a broken XML file.
Check errors inside your XML files, mainly within the /res/ folder
Common places are /layout/ and /values/, especially if you've changed one of them recently
Check AndroidManifest.xml. I find that often I change a string and forget to change the string name from AndroidManifest.xml.
Check that Android SDK Build-tools is installed. Window -> Android SDK Manager -> Tools -> Android SDK Build-tools
Make sure when you update the Android SDK Tools, you also update the Android SDK Platform-tools and Android ADK Build-tools. Build fails silently if they don't match.
If you can't find the issue, right click /gen/ -> Restore from local history... -> tick R.java -> click Restore. Even if it doesn't solve the problem, it will clear out the extra errors to make the problem easier to find.
This site suggests:
if you run a clean on the project it should regenerate all the generated Java files, namely R.
...and...
In Eclipse, under the Project menu, is an option build automatically.
That would help you build the R.java file everytime modifications are
made. The Clean... option is also there under Project.
This site suggests another solution.
I had the same issue. When I checked it out I found that the name of the XML resource under layout was not having the correct naming convention. It had some capital letters. So I renamed it to make all letters lowercase and the magic worked.
One reason the R.class can go missing suddenly is when there are errors in you XML files. For instance, when you add an XML file with uppercase letters in the name like myCoolLayout.xml which is not allowed. Or when you have references that don't point to existing files, etc.
In Eclipse, simply use Project --> clean to clean the project. The
R.java is going to be automaticly (re)-created.
If for some reason that dosn't work: Make sure your layout.xml files don't contains errors. Eclipse seems to be a bit buggy here: sometimes it doesn't mark the errors within the XML nor the package explorer. In such a case: Take a look at the "console" or "problems" view after using "clean". All errors should be displayed there. Fix them and redo a clean.
NOTE: It is NOT neccessary to fix the errors you get because of a missing R file! Just fix the XML files and other project errors and use clean!
Quick fix:
The package name in the manifest needs to be the same as the one in the /src folder, the /gen folder package will be automatically reproduced.
Detailed observation:
Observe the name of package in the /gen folder. In my case it was different than the one in the /src folder.
The package referenced in the manifest was that of the /gen folder.
I attempted to add a package with the name of the /src folder to the /gen folder too see what would've happened, but this did not solve the issue. I proceeded then to remove the package name that was not the same as the package name of the /src folder. This package with the name that did not correspond to the /src folder was recreated as soon as I removed it.
Since the package reference in the manifest corresponded to the one that was being senselessly recreated and that did not correspond with the package in the /src folder, this prompted to rename package = "oldPackage" with the package = "srcFolderPackage".
I had the same issue, and I finally found the problem: In the strings.xml, I did not keep the line <string name="app_name">program-name</string> which is present by default when creating a new Android project. I thought it was only used for the program HelloWord, which is the original program.
However, the AndroidManifest.xml refers to this value, hence:
=> A compile error;
=> the R.java isn't updated;
=> ID are not recognized...
Android has added in SDK build tool ADT 22 for the building mechanism. You just need to do the following steps.
Update Android SDK Tool
Update Android SDK Platform Tool
Update Android SDK Build Tool
Add the path of your build tool to the path variable. (path up to---- YOUR DIRECTORY-PATH\android-sdk\build-tools)
This will solve the issue.
If your R.java isn't getting generated, one of the solutions is to delete the layout file named "blabla.out.xml".
After deleting this file, try cleaning the project from menu Project -> Clean.
As a generalization of Glaux's answer, if you have any errors in the res directory, then R.java may not generate - even if you clean and rebuild. Resolve those errors first.
As an example: when you add an image file of say, "myimage-2.jpg", the system will consider this an error, since file names are limited to alphanumeric values. Do a refresh on your 'res' directory after adding any files and watch the output in your console window for any file name warnings.
If your OS is Ubuntu, I can provide some suggestion:
Install or upgrade ia32-lib:
sudo apt-get upgrade ia32-libs
Check if you have the right permission on the aapt folder:
cd ANDROID/adt-bundle-linux-x86_64-20130522/sdk/build-tools/android-4.2.2
chmod 777 aapt
Start Eclipse:
sudo eclipse
Run Project -> Clean in Eclipse
You 100% have an error in an XML-file, but the XML verification does not show you the error. This is the reason why you need to check your XML files first!
It is ALWAYS helpful to take a look at the Problems Tab in Eclipse. In my case, I was getting a "android unable to resolve target 'android-8'" error message that kept the R.java from being generated. So, I corrected the imported target to the one I was using in the default.properties file, then I performed a clean via Projects->Clean and voila! R.java is automatically generated! Hope it helps!
Cleaning project, closing Eclipse, re-opening it and launching my project finally made my R.java to reappear... Hope it helps
Make sure you are not importing
android.R;
R.java will never be generated if there are any errors in the res folder. For example, in the drawable subfolder there are two files which have the same name, one is icon.png and the other is icon.html.
You can see some error in the Eclipse console log window which is saying "Resource entry icon is already defined.". After deleting icon.html, you can clean or just delete the gen folder. You will find that R.java is created.
I've found that any file that has capital letters in the res folder will create this error. This happened to me with a PNG file I added and forgot about.
After reading through many posts and YouTube videos, I found that each of us have R.java missing for different reasons.
Here's how I fixed this in Eclipse:
Create R.java in gen folder manually and save.
After that go to Project and click "Clean"
The following message will display and your file will automatically be rewritten:
R.java was modified manually! Reverting to generated version!
For me, I had linked v7 appcompat twice. Anyhow, in Eclipse, right click the project name in Package Explorer or Navigator, go to Properties, Android, and uncheck any duplicates in the Library section. You may need to Build --> Clean afterwards.
There's obviously no one final answer to this, but here's another one I don't see here already:
I've had R.java disappear after (attempting) a Team Synchronize, and there were conflict resolution files in the project (i.e., thingy.xml.mine,thingy.xml.r35, etc.). Deleting them/resolving the conflicts regenerated R.
I had this problem. Accidentally I deleted this
xmlns:tools="http://schemas.android.com/tools"
which started causing build errors all over the project in my XML files as well as my Java files. As soon as I retyped what I deleted, it worked again :)
OK so it's clear that there can be a lot of causes for this problem. If you're on a 64 bit linux machine and you are just setting up the ADT for the first time, you may get this problem where R is not automatically generating. Check the console tab and you may see an error similar to:
'No such file or directory' while attempting to get adb version from '/home/patrick/code/android-sdks/platform-tools/adb'
If that's the case you need to install ia32-libs, using something like:
sudo apt-get install ia32-libs
See here for details: Android adb not found
I've came across this problem a few times. I found that if I didn't import the package R through my application's name, for example, if my application had the package name example.test then I found that I had to import example.test.R in order to access any of the resources.
If this wasn't imported then the resources that where getting returned were the default resources with none of my own included.
With that said if you find that you are only getting a list of default resources then just check to make sure that you're importing application_package_name.R and not android.R.
My problem was that appcompat was not in the same directory as my project.
I found this out when compiling my app with Ant.
Also make sure that you have the latest version of the ADT plugin, and open the Android SDK manager to update all SDK tools to the latest version. Check for updates in Eclipse itself as well. Non-matching versions caused the problem for me.
My problem was inside a menu file.
The compiler doesn't seem to warn you if strings which do not exist inside strings.xml are referenced in menu files. Check if your items in your menu XML files reference any strings which do not exist in your strings.xml. Usually in android:title.
For me, this error was caused when I tried to duplicate an existing res/menu instead of creating one with the wizard.
All of these answers could not work if you use Maven. The solution for me was to add
<genDirectory>${project.basedir}/gen</genDirectory>
to the configuration section of android-maven-plugin.
I found a solution why R.class is not made by Eclipse after making it again - 2 clean, build, etc.
The problem is here in strings.xml:
<string name="hello">Hello World, HelloAutoComplete!</string>
<string name="app_name">HelloAutoComplete</string>
These are by default created by Eclipse when you create projects.
Definitely you are changing the strings.xml for your own requirement. Sometimes you clear the string.xmls these two lines from your code:
It is making a problem in the AndroidManifest.xml file:
<application android:icon="#drawable/icon" android:label="#string/app_name">
<activity android:name=".HelloAutoComplete" android:label="#string/app_name">
So it can't communicate with strings.xml.
I changed my layout XML file name and found out later that of the XML file (widget provider in this case) still refers to the old layout XML which doesn't exist, and that prevented the auto generation/correction of R class.
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.
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.