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IntelliJ IDEA is not recognizing my java files as runnable and instead wants to run the class files. Any ideas of how to fix?

Anytime I try to run a java file by clicking run, it instead tries to run the class file and thus gives a no main method error.
When I try to right click on a java file and run that, it doesn't recogize it as a file that is runable.
I am still able to run programs from the command prompt but I would prefer to be able to run them in IntelliJ.
This occurred after trying to create a Class path when using JSon Libraries.
Edit:
Normally it shows java files with this icon:
But instead it's showing this icon for java files:
I think the change in icon might have something to do with it.
Edit 2:
the exact error I get is "C:\Program Files (x86)\Java\jdk1.8.0_181\bin\java.exe"...bunch of other program file locations
Error: Could not find or load main class sample.Main
Process finished with exit code 1

I had the same problem and found out that my src wasn't marked as Sources Root. To change this:
right-mouse click on your src
navigate to "Mark Directory As"
choose "Sources Root"
It will now recognize your files correctly and your main classes will be able to run again
IntelliJ not recognizing my .java-files
Problem solved

I had a similar problem.It wouldn't pick up ModlServer in any project. (Not just limited to the one I had open).
I had to file -> Manage IDE Settings -> Restore Default Settings
Note: I lost all my live templates, fonts, etc so just a heads up.

I restarted my computer and that somehow fixed it.

My issue was that I have multiple modules for my project and the module I was working on (where java files were not recognized) was not included in the main pom. I just added that module in the main (project) pom and it worked.

Right click on the project and click 'Add framework support' all directories and classes should now be the right type.

I've fixed this at Intelij2023 by using JDK17 as the JDK the IDE uses to import java source files.
Mind this JDK version does not need to be the same you use to build your project.
Go to: Settings > Build, Executio, Deployment> Build Tools > Maven > Importer
Set the JDK For Importer to zulu-17
I'm using zulu-17 as JDK for imports and coretto-8 to build the project (having JDK version 8 seems to be preventing intelij to properly recognize the project structure)

If you are using Maven or Gradle, try to re-import the project and see if that helps. Could be that your IDEA project has some incorrect settings in it set by mistake, so this way those would be removed.

After creating android project in Eclipse ADT, tons of errors show up

I'm using eclipse ADT (most recent version) to develop some android apps. I've followed the getting started tutorial at the dev.android.com and it worked just fine.
But when i tried to create another project with the same targets and sdk's, i've got nothing but errors:
Some errors and my sdk's:
That's the same sdk's i used before these errors started showing up.
What can be causing this?
EDIT: my project won't generate the R.java file

You might need to add a support library to your new project.
Check this link for downloading the support libraries -
http://developer.android.com/tools/support-library/setup.html#download
Please notice that you need to import them into your eclipse and then include one (preferably the newest, not sure about this) in your project.
EDIT:
Before downloading the support libraries you should first check if you have them already.
Try this, right click project folder in the eclipse package explorer, Properties>Android>Library>Add>select a library if you have one.
There might be an invalid library included in your project already, if that happens then you will see it in the Library>Add> menu, remove it and add a new one.

You might have clean your project ........
if yes.....you must check whether R.java file is present in **Project(your project)->gen->package name->R.java**
if not than u have to update Tool Folder in SDK manager

Importing Android project into eclipse gives me two project

I am importing the following project : ActionBarCompat-Basic from the Android Developers website into Eclipse.
by doing so: File -> Import => Android existing project.
However, in my package explorer, it creates me two projects :
1) The first project is named MainActivity
2) The second project is named tests.
Also, the two projects both have errors
Is that normal ? If yes, how can I solve the errors issue ?

Note, because you do not say wich project you are importing, this a blind answer.
You get two project simply because in the downloaded folder are two project.
To resolve errors first of all try to do a clean Project=>Clean... and select the projects you want to clean.
Unfortunately errors are common when you import project coming from around the web.
You should right click those projects, open Properties and check the Android tab, check if you are missing some library and try to figure out wich library is (or are).
Check Android 4.4.2 as build target.
Open the Java Build Path tab and open the Source tab, check if the gen and src folders are there, if not, add them.
If error are still there open the files marked with the error icon and try to figure out wich library they miss.
Check the Eclipse error Log.
I hope this help.

Problem with linking to other project in Android Eclipse environment

I am developing an Android application as an Eclipse project that uses classes from another Eclipse Android project I already have. When I originally imported it (New Project > Android Project > From Existing Source), it had a bunch of errors, but when I did Project > Properties > Java Build Path and went to the projects tab and added the other project, the errors went away. Unfortunately, when I ran the application, I got the following error in DDMS:
java.lang.NoClassDefFoundError: [package name].Config
[stack trace]
Is there something I'm supposed to add to the manifest telling it to look at the other package? If so, where would that be added?
Thanks in advance

Found the answer. It turns out that if I add the compiled class files into a JAR file using Eclipse's export command and then link to external jars in the Java Build Path, it works without having to change the Android Manifest at all.

Try using the File -> Import...
Then go to "Existing projects into Workspace" and choose the root directory of the project.
The one where are the src,res... folders

Your second project should be a library. Open project properties, select the Android tab and check "is library".
In your main project, open its properties, select Android tab also and click on Add in the library section and add your second project.

Android Eclipse Classpath - want to add classpath container path but eclipse won't let me

I'm using Eclipse to learn to develop Android applications in Java. I haven't used Eclipse before.
The project I'm trying to use (supplied by OReilly as part of 'Android Application Development') is MJAndroid. When attempting to run the project, the Run fails, and the Problems tab mentions com.java.Object can't be found, and Eclipse asks me to check the build path. Clicking
Properties -> Java Build Path -> Libraries, the message 'Unable to get system library for the project' is displayed.
On a working project, Properties -> Java Build Path -> Libraries has an entry for Android 1.1, which if I click Edit, has the classpath container path of com.android.ide.eclipse.adt.ANDROID_FRAMEWORK.
It seems a simple matter of adding the correct container path to my non-working project. However Eclipse seems determined to make this as difficult as possible. No matter what I chose to add - jars, externals jars, variables, libraries, class folders, external class folders, nothing seems to take the form of 'com.android.ide.eclipse.adt.ANDROID_FRAMEWORK' that the 'Android 1.1' entry on the working app has.
How can I add this namespace to my project so it resembles the working one?
I'm quite sure it's a problem with Eclipse's somewhat odd user interface. Frankly there' nothing I'd prefer more than a file to modify and set such information - my background is in Python, and the whole eclipse environment seems an unnecessary burden.

I had faced the same issue when I imported a sample code downloaded from the internet. I am using android sdk 1.5 with 0.9 ADT plugins. Here is a simpler way to fix the andoid library reference issues
Right click on the project which has
issues and select properties
Select the appropriate Android build
(1.1, 1.5 or 1.5 with google api) and
say ok
Again right click on the project and
select "Android Tools > Fix Project
Properties"
Fix the imports once (if required)
Refresh the project and you should be
ready to go without any manual
editing

I faced this same problem after importing a project through GIT. The problem was that I didn't have the same target android platform installed, and the build path somehow got corrupted.
The first obvious thing i did was changing the target sdk in the project.properties, but even after cleaning up the project and Android Tools > Fix Project Properties, it didn't help and I was still getting the build error.
My solution after wasting close to 1 hour trying to figure this out?
RESTART ECLIPSE
Everything worked fine after that. Eclipse is pretty fickle. Only through years of experience you'll then understand her well. :)

Had the same problem and it turns out the Android SDK Location was not set which was a really simple fix. Go to Window->Preferences, click on 'Android' on the left hand menu, fill in the location of the Android SDK (e.g. C:\Program Files\Android\android-sdk) and click OK. Everything worked fine for me after that.
Found the answer in this set up guide: http://developer.motorola.com/docstools/library/Installing-Android-Dev-Environment/

Sometimes Eclipse can get a bit funny (technical term) with classpath container resolution.
You have a working project in your workspace, so you can rule out plugin installation issues. You could try opening the .classpath file (hidden by default, select the triangle in the top-right of the Package Explorer view, select Filters... and uncheck .* resources) and manually adding the container declaration.
`<classpathentry kind="con" path="com.android.ide.eclipse.adt.ANDROID_FRAMEWORK"/>`
You may then have to close the project and open it again (right-click->Close Project) before Eclipse recognises the change.
You may also find that there is an Android builder and/or nature. If you compare the .project files for the working and non-working versions you may see entries for Android builders/natures. Copying the relevant entries may resolve the issue.

sometimes, eclipse can help you.
In Android projects, click right button on the project-> Android Tools -> Fix Project Properties.
It's usefull in class path errors!!
Luck!

I would verify you have the correct version of Java installed as well as the Android SDK. I would recommend installing/reinstalling the ADT plugin in your eclipse, makes it alot easier to create the android project.
http://developer.android.com/sdk/1.5_r2/installing.html

Also. I guess the path of the Android SDK must be setup correctly. This happened when I was overloaded with projects and I decided to create a new workspace copying some existing stuff into it.
Seems that the new workspace requires you to setup these details too once again
Is that setup properly?