No generated R.java file in my project

Question

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.

Solution 1

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.

Solution 2

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.

Solution 3

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

Solution 4

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

Solution 5

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 !

View more solutions

Comments

[Octavian Damiean]

@Jonas: Please post up your imports.

[Jonas]

The project target is set, but I don't know about "min sdk level". Where can I see if it is set? In default.properties I only have target=android-7

[Octavian Damiean]

@Jonas: this means that the target build is set to Android 2.1.

[Octavian Damiean]

@Jonas: exactly. The import section of your main application.

[srinathhs]

There is also an attribute in manifest <uses-sdk android:minSdkVersion="8" />. Did you see any kind of "errors" in the problems tab or Console?

[Jonas]

When I change build target from Android 2.1 to Android 2.2 the R.java is generated. But when I change back to Android 2.1 and after I do Project>Clean then the R.java is deleted again.

[Octavian Damiean]

@Jonas: Don't change the target build. Have you tried what I've mentioned?

[Jonas]

When I remove import android.R I have two errors in the Problems view. They are R cannot be resolved to a variable in Notepadv2.java and error: Error: String types not allowed (at 'layout_height' with value 'match_parent') in note_edit.xml

[Jonas]

Yes, see my comment to WarrenFaith

[Jonas]

Yes, Project > Clean doesn't help me. After that I get two errors in the Problems view. See my comment to WarrenFaith

[Octavian Damiean]

Well if your target build is 2.1 then match_parent won't be available since it was added in Android 2.2.

[Jonas]

In Properties > Android I can only choose a Build target and it is Android 2.1 which I want. There is also an empty Library section in the same dialog.

[Jonas]

@Octavian: Ah, so the XML failed to parse, so no R.java is generated. Now when I change build target to Android 2.2 it seem to work. You could add that to your answer.

[DeRagan]

Yes in build target you should have selected 2.2 and yes you were indeed using the incorrect SDK version :)

[ina]

after wading through legions of google groups mess trying to find this solution... what'd you know, it was on SO the whole time.

[Saher Ahwal]

why getting rid of the import solves the issue? That doesn't make sense to me?

[Octavian Damiean]

@Saher Because having the R file of another package in your class will definitely screw up everything.

[m2web]

This was close to the problem I was having--I think somehow I was missing something in the buildSpec section of my .project file. Not sure how it got that way, or the correct way to fix it, but I basically copy/pasted from a working project and got R.java building again.

[ademers]

That did the trick. Thank you.

[Larry McKenzie]

I am looking for this new option where can I find it?

[amar]

Right Click on project > Android Tools > Run Lint : Common Errors

[Arnaldo Ignacio Gaspar Véjar]

Finally i solve this problem updating the Android SDK Tools and restarting eclipse, very thanks

[marzapower]

Thank you! Why do they always have to break things???

[Linson]

Thats really worked, Thank you very much.

[Ankit]

Thanks.. That worked, you saved my day.

[Jay Snayder]

Yep, same here. Another thanks. I thought that I had already gone through that process, but it must have gotten interrupted in between when I was closing eclipse during the download and it never finished.

[Vivek Warde]

If this cannot solve this issue then other answers can be considered !

[sjngm]

I don't know if it's a new feature, but my layout files have an underscore in their name and everything works fine.

[avasal]

+1 this works, but make sure there is no other error in the project