R file is missing android

问题:

i was using Eclipse Helios but due to performance issues i changed to Eclipse Galileo and installed the ADT plugging, and added my sdk folder to Elcipse Preferences. Now R.java disappeared from all of my projects. How can i fix this, i did Project/Clean but that won't generate the files, there's nothing wrong in my xml and there's no out.xml in any of my projects.

Thanks in advance

回答1:

I had this same issue today and figured it out. The reason this happens so often when including external/example files is because often times these examples reference layouts in your application, but do not have access to the package and therefore cannot see the R.java file in that package. to make things clear, here's the beginning of the R.java file:

/* AUTO-GENERATED FILE.  DO NOT MODIFY.
 *
 * This class was automatically generated by the
 * aapt tool from the resource data it found.  It
 * should not be modified by hand.
 */

package com.conceptualsystems.dashboard;

public final class R {
    public static final class attr {
    }
    public static final class drawable {
        public static final int csc_logo=0x7f020000;
        public static final int icon=0x7f020001;
    }
    public static final class id {
        public static final int activation_code=0x7f070012;
        public static final int alpha_bar=0x7f07000b;
        public static final int alpha_label=0x7f07000a;

notice the package name is whatever the package name of your application is. .java files that are not included in this package (ie, your example code you just dropped in) will need to explicitly reference that package file like this:

package com.example.android.apis.graphics;

import android.app.Dialog;
import android.content.Context;
import android.graphics.*;
import android.os.Bundle;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.SeekBar;
import com.conceptualsystems.dashboard.R;

the last line is the one to pay attention to. after importing the resources explicitly, the resources will be available in your example code.

回答2:

In my experience there is a mistake in the xml somewhere. Eclipse will no doubt tell you where. After I fix the error R appears.

回答3:

Sometimes when you clean your project the R file disappears, I had the same issue.

The way I fixed it was:

-Make sure all the "import android.R" was removed -Clean again (if this doesn't fix it, restart eclipse and try again)

Or

-Put the pointers to R file in comment f.e. // setContentView(R.layout.main); -If all the pointers to R file are in comment, you should get only warnings in the file, and hopefully errors somewhere else. -Fix the errors and then uncomment the pointers. Sometimes eclipse ignores some errors and drops the R file and then says nothing about it, which is annoying, but this will fix it. :)

-If this still doesn't work, you can try create a new project and copy paste your code in it.

回答4:

created new project in eclipse, then I imported the sample files into it, yet still same error. You might want to try the following:

• In Eclipse -> Right Click on Project -> Android Tools -> Fix Project

• made sure that all resources are lowercase.

回答5:

Try unclicking and re-clicking build project automatically in the project dropdown, closing the program each time. There have been know bugs about this for a while but there's not always a set fix.

When it once happened to me it turned out it was because i'd named an .xml file with a capital letter. Worth checking.

回答6:

I had this problem when upgrading from Eclipse/Helios to Eclipse/Juno.

I set up the IDE and then imported an existing (working) project. If I then ran it in the emulator it ran but in its original version although the java code was for the latest version.

I then did a Clean (as explained in many other posts) and a (re) build but then ended up with host of errors due toSmissing R.java file.

The problem turned out to be some 'errors' in the layout xml files which had not been recognised by Eclipse/Helios. Specifically, in my case, there were some layout_width='match-parent' (and height) settings which Juno objected to. I tried changing those directly in the xml files but Juno wasn't having it and still reported it as a 'match-parent' error (although it had clearly been changed).

The only thing to do was to go to the graphical layout, right-click to get Properties and then change the Width and Height properties there. Also, as they were already showing as 'fill-parent', I had to first change them to 'wrap-content' and then change them back to 'fill-parent'.

Once I'd done that for all instances of 'match-parent' I could then do a build and run the latest version in the emulator.

回答7:

There are mistakes in res. Once I have the same xml files in layout and menu, generate failed, no R.java generated.

回答8:

Localize the correct R. package import, should be in your packages.

ex. import com.yourdomain.test.R;

回答9:

This is where ADT Android project is a bit different from a normal Java project. An android project requires a constantly updated persistent R.java file. Among other things, the R.java file has all the resources IDs provided in your App and maintains interface's consistency.

So first make sure R.java file is being generated for your android project.

• To find that out first go to the top of ADT (Eclipse) and clean the project PROJECT->CLEAN
• If the 'Build Automatically' is checked the R.java file should be created now.
• To confirm, you can simply search the file in the project folder. You won't find it if its not being created.
• If R.java is not being created, there is 90% chance that there is some issue with one of your interface *.xml files. Which usually resides in res->layout->activityXXXX.xml

Fix the interface file/s (try making it very simple with a single button or something) and R.java file will be generated by ADT automatically. At this point you should start noticing R.layout.XXXX not found type errors in your main program/activities. Which is a good thing, because now you can create/rename correct layout items and fix your project.

Just my 2 cents....

回答10:

same happened to me, corrected checking any errors in res xml files, and changing target 1.5 to 2.2 android (on my case) this usually happens to me when importing external code or online source code from examples or other developers.

回答11:

Hi I had this happen to me this weekend.

The actual reason this had happened was that I had unchecked the update option for Android in the preferences as it wasn't working with the previous version of Eclipse. Now although the eclipse was seeming to run fine, when I PROJECT->CLEAN the project the R.java was missing.

Try re-ticking the android update option (WINDOW -> PREFERENCES -> INSTALL/UPDATE).

This completely solved my issue and I did not have to both with any hassle of scanning each line of my many xml files or my image resources.

Hope this helps someone :)

回答12:

I just Encountered the same problem.

Turned out my Source control had inserted an Addedd>>>>>>>>>>>>>>>> section to my mainifest file.

All I had to do was fix the manifest file and then all the errors disappeared.

回答13:

This happened to me while adding some new resources to my project. The R file is build after every resource update.

The error in my case was incorrect file name. One of the image resources had a capital case letter in its name and that prevented the build from creating the R file. Changing the name simply worked.

I would suggest that when you add too many resources at a time, just make sure of the naming conventions for them. Its easy to miss such things.

Resource conventions: http://developer.android.com/guide/topics/resources/providing-resources.html

回答14:

I had the similar problem. That was because I saved a drawable file picture.jpg as picture.png, as soon as I changed the name to previous one it started working. hope this would help someone in future