In my new project I always have to import:
import com.abc.R;
or the problem: "R cannot be resolved to a variable" appears.
But in my other project I don't have to do that.
What is the difference and is there any problem?
This might happen when you have an error in your xml layout and then you try to clean the project, you get this error.
Try to build the project, if it doesn't work, start a new one and copy the contents. Now that should work.
In general, to make it work:
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.
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. Turn it on and build your
project.
Mistakes in your xml views could cause the R.java not to be
generated. Go through your view files and make sure all the xml is
right! Remove, if any import android.R;
Restart your IDE.
Perhaps in your other projects the classes referencing R are in the same package as R?
i am new in android when i create a new project using android application project following error occurs.I tried to rename package but not working also tried to refresh and restart eclipse but not working.
Seems to be like,There are some bad stuff in the resource folder,like unformatted image in drawable(imagename used in drawable should contain only small letters numbers or underscore) or something like that.Then remove android.R from import section.After that clean the whole project and check
Remove import andorid.R and check if you have errors in your resource files. If you have errors fix them. Clean and Build your project.
Import R like this import com.example.tablelayoutonly.R;
Remove import android.R and use your layout import.
I hope it's error in android sdk (file missing) so you need to download new sdk and try again. After that clean your project and fix by right click on your project Android Tools -> fix project properties
You should follow these steps:
1 - Check If activity_main.xml exists in res/layout folder
2 - check If man.xml exists in res/menu folder
3 - Change the name of your package automatically you should change it also in your AndroidManifest file
4 - drop the line import android.R; because with that import you oblige you app to use default android layout instead of yours.
I have a problem with R in android. I have a project with some packages. I changed the name of one package. I saw that the package with the same name was in "gen" folder. When I changed the name, I cleaned the project and this package disappeared from "gen" folder. Now I have error with
R cannot be resolved
and in all classes I have errors with R. How I can repair my problem?
So i think this is answer
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.
Reference.
And try to clean your project and if you have
import android.R;
remove this line and clean it again.
remove
import android.R;
and do Project > Clean...
Remove this import from your code if it is there.
import android.R;
Clean your project and rebuild the solution again.
If it isn't what the two other answers are, I've had a similar problem that related to me having an error in one of my XML files. Since the XML file has an error, eclipse fails to build your project. A failed build somehow messes up the path to the R.java file. So if you clean up your XML files and build the project, it should fix itself.
I am new to android and making my first application.
I have a problem resolving R.layout.main
The main is auto generated in my res/layout.
I have already imported android.R
but it is still not resolving "main"
If you are creating a new application for android in eclipse, then R.java file is auto generated in your application's /gen directory, And your R.layout.main is resolved automatically, For that you don't have to import any R file in your activity class..
Just remove android.R any any other R file import statements, Clean and rebuild your project it works fine..
Also make sure Your project doesn't have a any error, If its present then it s prevent to generate R.java file in /gen directory..
Instead of android.R you must import the your package name.R...
Have you imported "your-package".R?
You can find it in "gen" directory.
If R.java is not auto generated, probably there is compile time error, check your ide's messages.
By the way, you define "your-package" in your AndroidManifest file.
Quick solution:
Remove android.R and just import your package.R file by doing Ctrl+Shift+O
More info:
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.
Look at your imports. There is android.R imported, 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.
R.java file should be auto generated, but I could not find it. So I just deleted my project and created it again and this time everything went fine - I've got R.java and the error resolving R disappeared.
Problem: Not resolving R.layout.main
Solution: In your Activity Java class import as following
import [Package Name].R
Example >> import com.example.tutorial.R
This question already has answers here:
Developing for Android in Eclipse: R.java not regenerating
(64 answers)
Closed 9 years ago.
I am doing the Notepad tutorial, exercise 2. I started by creating a new Android project and chose Create from source to import the downloaded source files for the excercise.
But now I get many errors in Eclipse, and the problem is that there is no generated R.java class. How can I solve this? The folder gen/ is empty.
I have errors on Notepadv2.java and in res/layout/note_edit.xml and both seems to be related to the fact that the generated R.java is missing.
Here is my import statements in Notepadv2.java:
import android.R;
import android.app.ListActivity;
import android.content.Intent;
import android.database.Cursor;
import android.os.Bundle;
import android.view.ContextMenu;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.ListView;
import android.widget.SimpleCursorAdapter;
They are created by the Eclipse command Ctrl+Shift+O.
Go to Project and hit Clean. This should, among others, regenerate your R.java file.
Also get rid of any import android.R.* statements and then do the clean up I mentioned.
Apparently Jonas problem was related to incorrect target build settings. His target build was set to Android 2.1 (SDK v7) where his layout XML used Android 2.2 (SDK v8) elements (layout parameter match_parent), due to this there was no way for Eclipse to correctly generate the R.java file which caused all the problems.
After one whole day trying to find why R file was not generated, I found that after install Android SDK Tools r22 a new option in Tools was available: Android SDK Build Tools.
After installing it R file was generated again.
now you have imported android.R instead of your own R... Try to take a look on your "problems" view if you have errors in one of your xml files... get rid of the import android.R and comment out all usages of R.*
Cleaning should help when your project has no other errors, so check your xml files or file naming in your res folders
Probably u might be using a incorrect SDK version. Right click on your project. Select Properties-->Android. Note that 2.2 is the latest SDK. Check it and see if it gets compiled...
Edit
Also Do a clean after that
I Had a similar problem
Best way to Identify this problem is to identify Lint warnings::
*Right Click on project > Android Tools > Run Lint : Common Errors*
That helps us to show some errors through which we can fix things
which make R.java regenerated once again
By following above steps i identified that i had added some image
files that i have not used -> I removed them -> That fixed the
problem !
Finally Clean the project !
I colleague of mine has this problem - a restart of eclipse fixed it.
Update Android SDK Tools in Android SDK Manager for revision 22.0.1.
It worked for me.
Remove the 'import R.java' line from your code. Its done by Eclipse in order to solve the problem.
Go to "note_edit.xml" file. Wherever you find "match_parent" as an attribute value, replace it with either "fill_parent" or "wrap_content".
Do a clean build. R.java will be generated automatically.
If you got this problem, it means "match_parent" property is not supported in your content. Instead, "fill_parent" is used.
"fill_parent: The view should be as big as its parent (minus padding). This constant is deprecated starting from API Level 8 and is replaced by match_parent. "
Do you have installed the android plugin ?
Your project must be of the android type.
This is actually a bug in the tutorials code. I was having the same issue and I finally realized the issue was in the "note_edit.xml" file.
Some of the layout_heigh/width attributes were set to "match_parent" which is not a valid value, they're supposed to be set to "fill_parent".
This was throwing a bug, that was causing the generation of the R.java file to fail. So, if you're having this issue, or a similar one, check all of your xml files and make sure that none of them have any errors.
I just had a problem where a previously working project stopped working with everything that referenced R being posted as errors because R.java was not being generated.
** * CHECK THE CONSOLE VIEW TOO **
I had (using finder) made a backup of the main icon (not even used)
so one of the res folders (hdpi) had
icon.png
copy of icon.png
Console indicated that "copy of icon.png" was not a valid file name.
No errors were flagged anywhere else - no red X in the res folders....
but replacing the spaces with "_" and it is all back to normal....
I have faced this issue many times. The root problem being
The target sdk version is not selected in the project settings
or
The file default.properties (next to manifest.xml) is either missing or min sdk level not set.
Check those two and do a clean build as suggested in earlier options it should work fine.
Check for errors in "Problems" or "Console" tab.
Lastly : Do you have / eclipse has write permissions to the project folder? (also less probable one is disk space)
I've also experienced such issues as R.java being missing, and also eclipse complaining there are errors in my code (displaying red X icon against class files) when there were no errors.
The only method I've found for solving this is to clean the project by selecting Project > Clean
This seems to solve the issue for myself, running Eclipse 3.5.2
yeah i have the same problem.i fixed it by
selecting Project from the tool bar clean the project
also reset the build automatic option
some times needed to change the name of xml file match format [a-z][0-9]
capital letters must be changed
It seems that when you change to the latest SDK (2.2) building no longer generates an R.java file. Or at least not in the way we're used to. To solve this delete the package underneath the gen folder and clean without building. This solves the issue for me.
I've got that problem because of some internall error in Android plugin. When I've tried to open some layout xml, I've got error:
The project target (Android 2.2) was not properly loaded.
Fortunatelly in my case restarting Eclipse and cleaning the project helped.
This could also be the problem of an incorrect xml layout file for example. If your xml files are not valid (containing errors) the R file will not re-generate after a clean-up. If you fix this, the R file will be generated automatically again.
According to my experince i can summarize :
1.The problem is mainly refering to syntax issues that can be
occured on xml files.
2.You might copy the AndroidManifest.xml accidently to subfolders .
1.One file is an extension undefined .
After checking all of these Go to Project->Clean or just remove the /bin and /gen folders.
Just Restart the Eclipse will solve this Issue as the workspace will be freshly Build ! go to
File -> Restart
Its the easiest way to avoid frustration by going it into Build,properties,blah blah.....
Here's another one: I was just about to cry, but managed to get my beloved R.java back:
I hadn't updated anything in my Android installation for quite a while. I needed a feature and ran the SDK Manager. Besides what I needed I basically checked everything it wanted to update. Afterwards my R.java disappeared in Eclipse.
To make it short, in the SDK Manager there was a new entry "Android SDK Build-tools" that I guess wasn't there the last time I had updated. It's kind of an obvious name, really. After I installed that one Eclipse gave me my R.java back.
java .... than debug..
or
Remove the 'import R.java' line from your code. Its done by Eclipse in order to solve the problem.
Go to "note_edit.xml" file. Wherever you find "match_parent" as an attribute value, replace it with either "fill_parent" or "wrap_content".
Do a clean build. R.java will be generated automatically