I am running into a problem when trying to duplicate a project in STS.
I am getting lots of error-messages of type
"Import XY cannot be resolved..."
in my code which runs and builds completely fine with maven and which is a more or less exact copy of the original project (with different artifact ID a.s.o. in the corresponding pom) which is shown as error-free.
What I did until now:
I wasn't sure how STS-duplicate works and thought that some configuration may have been duplicated but would have needed some changes, so I created a new project and inserted the code manually in manually new created classes and added the needed dependencies to the pom.
Again this compiles and runs perfectly while still showing the import errors.
Did anyone run into similar problems and has a solution to this?
(I had something similarly strange in the past where STS showed an error on project-level but no file in the project would have an error-indicator.)
Run a Maven -> Update Project..., that should help... :-)
I followed the getting start video on Jetbrains website to setup IntelliJ IDEA 13.1 Community Edition to work with Scala. Scala plugin v0.36.431 had been installed. While I created a new Scala SBT project with wizard, there was no src/ directory structure generated in the project. Only two sbt files were generated:
scala-course/
├── build.sbt
└── project
└── plugins.sbt
From the video and other document I know that there should be a src/ directory structure, including src/main/scala, src/test/scala, etc. sbt uses the same directory structure as Maven for source files by default.
I can create those folders manually and mark it as source root. However it is trivial. So my question is: Why IntelliJ IDEA new project wizard doesn't generate the directory structure as said in document? Was I doing something wrong? I checked the preferences and couldn't find anything that seems related.
Normally it should create these folders automatically. It may take a while though - it takes couple of seconds in my case.
When creating project make sure you have selected Scala -> SBT, then proceed with the wizard.
Once the Finish is clicked, the project will be loaded. This part takes couple of seconds, and I can see no src/main/scala nor src/test/scala generated until it's done. Observe the bottom of the screen to see when it's done.
Once the process is finished, you'll see the folders.
If that's not the case, check the settings. You should have the Create directories for empty content roots automatically checked. You may want to check Use auto-import to automatically propagate changes in the build.sbt.
After changing the settings (if the change is required) you may need to refresh the project, as seen in picture below.
This can also happen if you do not have a JDK selected. For some reason you no longer get the option to select an SDK so you must make sure you have configured this before hand. To fix this do the following:
From the welcome screen, go to
Configure -> Project defaults -> Project structure and add the jdk.
Source:
What's the reason for "Error:Cannot determine Java VM executable in selected JDK"?
Thanks to lpiepiora, with his hint I find out the reason.
Because my sbt is newly installed, there is nothing in ~/.ivy2/cache/ and ~/.sbt/boot/. sbt needed to download required dependencies from repositories on network. It happened that my proxy to internet had something wrong, download stuck.
And also need to notice that, if quit IntelliJ IDEA when sbt is running in background, the next time you'll get error of waiting for some lock file. Have to remove the lock file on filesystem and restart IntelliJ IDEA again.
After fixed the network problem, everything work as promised. It requires several minutes, depends on network speed, to download required jar files. After finished, the src/ directory structure is created.
I followed the instructions in this thread but I had a java crash in the final phase in sbt with the configuration bellow and I think this info maybe useful:
The problem happened with IDEA 2016.2, sbt 0.13.8 (I tried later to import using 0.13.12 but the crash was the same), scala 2.11.8 and ubuntu 16.04.
The only way I could make it work was to use java 8 instead of 9.
error: error while loading package, Missing dependency 'object java.lang.Object in compiler mirror', required by /home/jbamaral/.sbt/boot at xsbt.boot.Boot.main(Boot.scala)
...
stack log here
...
[error] scala.reflect.internal.MissingRequirementError: object java.lang.Object in compiler mirror not found.
I have exactly the same problem as in this question: Eclipse: Using "Open Declaration" ... in a Scala project
However, I'm using the latest Scala IDE in version 3.0.2 (I have downloaded the Eclipse bundle from the site), and I would assume such basic functionality works by now, and apparently it's me who have something misconfigured.
I have created a new Scala project. Then I open some standard library class/trait/whatever, let's say scala.util.parsing.combinator.JavaTokenParsers. The source is neatly displayed, but when I try to show class hierarchy, I get the message: The resource is not on the build path of a Java project.
Also, searching for references etc. won't work.
I guess it is a matter of properly configuring the build path? Or maybe I should somehow attach Scala library sources to my project? But I can see the source, so aren't they attached already?
Here is the snapshot of my project configuration:
UPDATE:
By playing a bit with setting/resetting build path stuff, I managed to get rid of pop-up warning but the class hierarchy comes up empty and when searching for references I get only hits from my own sources, nothing from standard library.
In another workspace I also tried randomly adding and removing scala-library jars and got it work almost, but the type hierarchy comes up only with super-classes, without any sub-classes (which renders it quite useless). Searching for references works ok though.
Funny thing, I cannot make it work in my original workspace...
Gotta love Eclipse.
Your build path is not configured properly.
If you take a look under Scala Library[...] you have scala-library.jar we can only see one top-level package scala. There should be numerous other packages besides that. (Ruled Out)
I would recommend you follow these steps
Right-click project, build-path, Java-build-path, Libraries and make sure that the correct library is referenced there.
If it is the one you need, Try to remove this library and add it again, then clean and re-fresh the project. Also try this step in a fresh workspace.(something must have messed up this workspace )
Lastly. Goto the path D:\Eclipse For Scala\configuration\org.eclipse.osgi\bundles\286\1\.cp\lib and verify the sizes of the jars there. There should be 6 jars there and the size of scala-library jar should be around 6.8M. If size is smaller, consider re-downloading
I've got a scala project that compiles, runs and tests fine when using SBT from the command line. However, when building the project in intellij, it seems every class in the project has this error in the event log, causing the build to fail:
SendCommandToService is already defined as case class SendCommandToService
case class SendCommandToService(service: String, commandName: String, keys: Array[String], values: Array[String])
^
For me, the reason is that both myproject/src and myproject/src/main/scala are marked as Source. So IntelliJ failed to build myproject/src/main/scala due to above errors. Unmark Source from myproject/src (in IntelliJ, File->Project structure, select myproject Module, select src folder in Sources Tab, remove it from Source in the "Add Content Root" pane) solved the problem.
It means there are two compiled classes with identical package and class name found in your classpath. One compiled by sbt, one compiled by IntelliJ.
One of the following should be able to solve the issue:
try to generate IntelliJ .iml file with sbt-idea rather than import directly.
sbt clean before click Build -> Rebuild in IntelliJ
when rebuilding with IntelliJ, make sure sbt is not running
I ran into this issue today on IntelliJ 2021.2.1 and according to this page it's some issue with IntelliJ's incremental compiler for Scala, so the solution is to change the "Incrementality Type" from "IDEA" to "Zinc" in Preferences -> Build, Execution, Deployment -> Compiler -> Scala Compiler
For me, the solution was to double check the source folders in each of my modules in IntelliJ.
File > Project Structure > Modules and for each module, double check that the Source Folders only contain your intended folders, e.g. src/main/scala, and do not contain any generated sources (e.g. target/scala-2.12/src_managed/main.
I had the same problem and #Max is right, there is a conflict with the compiled classes, but the solution provided didn't work for me. It turns out that I was using sbt-idea to generate the IDEA project structure as a workaround of an Intellij IDEA 14 + scala plugin bug on the SBT import, that is not fixed yet at the time I write this.
In order to fix it, I had to remove src_managed/main/controller that was in conflict with src_managed/main in the Module settings because of an sbt-idea bug. So double-check your module source folders and make sure you don't have subfolders in conflict with a parent folder already declared as source.
You need to change "Settings -> Build,Execution,Deployment -> Scala Compiler -> Compile order" from "Mixed" to "Java then Scala".
If you have compile the project previous, you should first run "sbt clean".
I had a similar issue repeatedly both within Idea and without: plain SBT.
It turned out that CVS stores copies of some *.scala files in subdirectory CVS/Base, which SBT apparently tries to compile. The problem went away when I deleted the CVS subdirectories.
Problem is caused by duplicated line in .idea/modules/<your_project_name>.iml file. Check if you do not have duplicated <source_folder> tag.
In my case I had the same problem with all classes in src/test/scala path, and after removal duplicated tag for this path, project build fine.
Do you have any other files in your project with an SendCommandToService in them?
You could try renaming it to something else, see if that works
If you want to keep the same names, you can put them into separate packages.
Or have them in different encapsulating objects
object traitdemo{
object Ex1{
...
}
}
object otherdemo{
object Ex1 {
...
}
}
that will work even in the same file
In my case problem solved by change ScalaTest template configuration in Idea. I select use sbt, disable print info, remove build before launch.
I like to use SBT for clean/package/test on specific module. I also use mixed Java/Scala classes in test (but I replace compile order to Java than Scala).
At least now I can test from IDE withot this error.
PS: Now I disable use sbt. My tests work fine (but I'm not sure, that they will work).
PPS: New tests not runs before compilation. It is disadvantage of removing build (and, maybe, of disabling use sbt). But this extra build cause problem with dublication, as I think
File -> Invalid Caches/Restart worked for me. All other answers here did not.
After the sbt compile I had to mark the folder as Generated Sources Root because I needed those files for compilation.
I'll just add mine to the list in case anyone else made this beginner mistake: I temporarily "saved my progress" by doing cp Foo.scala Foo-save.scala, forgetting that sbt would try to compile all the .scala files in the directory.
(I don't know, I guess I was thinking of programming languages where any file not explicitly included was ignored ...)
Of course, since both the main file and the "temporary backup" file defined the same classes ... yeah.
I had the same error message and it turned out that IntelliJ for some reason created duplicate copies of some existing source files. For example I had a file Attribute.scala that was tracked with git and then there was an untracked file Atrribute 2.scala with the same contents in the same directory (which I never created). This was of course a problem, because the compiler considers them part of the project, hence the duplicate object definition error.
I am not 100% sure when this happened (I suspect it was during git rebase). So, if you run into this problem again, it's also worth checking with git status if you have some untracked files which duplicate contents of tracked files.
Remove the untracked files and the problem is solved.
Kudos to this question thread, it helped me to solve this issue.
My case is a project with the mix of Scala, Java and Avro schemas.
IDE: IntelliJ IDEA 2022.1.3
How I solved it step by step (in IntelliJ):
File -> Project Structure
Project Settings -> Modules
Now we need to fix the "source" files. I searched for target/scala-2.12/src_managed in each module and marked it like “Source directory” (blue colour).
Unmarked all other paths like target/scala-2.12/* in all modules (in my case it was target/scala-2.12/src_managed/main/compiled_avro). As an example from my project, I left only these sources in one of the modules: target/scala-2.12/src_managed , src/main/scala.
Save the changes and rebuild the project.
ADDITION: Oh, and looks like sometimes this error occurs when you compile your scala project (with avro files) outside of the IntelliJ. For example when you build a project using sbt externally and then run some tests using the IntelliJ -> class already defined error occurs (or is not a member of package error). In such case: you need to run sbt clean compile externally first and go to step #1.
this happen when you incorrectly src/main/any other folder as Sources Root. Please check if you have any such cases. If yes, then Unmark those by righclick on it. then clic one level above of your groupId starting. Lets say your package is com.company.test and com may comes under java or scala, then right click on that(java/scala) then Mark as Sources Root.
In my case, the problem was the protobuf Idea plugin:
Remove the idea protbuf plugin.
Close Idea
Remove all folders related with idea (.idea and .idea_modules)
Open Idea and Import the project again.
I had a package structure which I changed, and this lead to the corresponding folders in /bin/ being removed, so now I get a ClassNotFoundException.
More specifically, I had the ususal /src/ and /bin/, and inside /src/ I had /main and /test, and this was presumably mirrored in /bin/. I shuffled the files around a bit and ended up with /main/model/ and /test/model/.
I have tried to manually create the corresponding folders (mirroring the packages in /src/), but this does not seem to help. I managed to compile the classes in one of the packages, but not in the test package, since it uses ScalaTest* and I didn't manage to compile the classes with the scalatest jar file (or something was wrong with the classpath).
So my question is:
How do I fix this within this peoject? (I don't want to simply create a new project and copy the source files over)
I'm guessing that I should learn more about build systems to be more resilient to such annoyances in the future? If so, what should I read up on, specifically to become better at troubleshooting and having more fine grained control over the build in the context of IDEs in the future (making builds independent of IDEs is not a priority for me at this point)?
An answer to one of these questions would be sufficient.
*All the source files are .scala files, if that might matter.
Udate
I did a clean of the project (project -> clean). This seemed to fix the problem: I was able to run the test classes from within Eclipse. All the binary files were in there, too. I made a new package, main.controller, with one class, and when I tried to run it, it said that it couldn't find the class. I tried to run the tests again, but those gave me a ClassNotFoundException, too. When I looked in /bin/ it turned out that all the folders and files were gone. I've tried to clean the project again but to no avail. I don't understand how I was able to clean the project, but now it can't fix it?
Update 2
To test if this was reproducible with a Java project, I made a Java project with two packages; main and test. I had the main class in main, which used a class from test (so there were dependencies across the packages). It ran succesfully. Then I added packages so that I had main.model and test.model and moved the corresponding files there. It also ran. Then I tried to delete all the files and folders in /bin/, and then the main class would not run. But if I did a clean of the project, then it cleaned it succesfully and the Main class was able to run. Then I made a Git repository for it, placing it outside of /workspace/ (in my git folder) and tried to do the same there. Eclipse was able to clean the project succesfully everytime.
So I don't understand why it can't manage to clean my Scala project.
I had errors in the "Problems" tab (Window -> Show View -> Problems). Now that I've made them go away, my /bin/ is correct and I can run both my Main class and my tests. This Question helped find out what the problem was:
Scala project won't compile in Eclipse; "Could not find the main class."