Using Java8, Eclipse Mars 4.5
I have a simple Maven project with a pom and a single java file, in a folder. I do the File -> Import -> Existing Maven Project -> Point to my folder. Eclipse does its thing sucessfully creates the project (no errors). But with somewhat of a complex folder structure that I am able to edit (with some difficulty). My project file structure is:
Project
/classes
/pkg
/.class
/src
/pkg
/.java
I originally see my java file (but not in the /src), I see all my dependent jars. After some doing (open/new etc) I am able finally compile my java class- I see all the generated class files.
But I am unable to run it. I do have my main class specified in the eclipse run configuration.
I don't have the Run As enabled.
I try run java application, get error:
Could not find or load main class 'myclass' (I do have the main method)
If I try Maven build (M2 the red icon), initially I got 'no goal specified' error, added <defaultGoal>install</defaultGoal> to the pom. I do get BUILD SUCCESS
But still no run? What am I missing.
I went the maven project route to simplify, but
Thanks
This problem was finally solved by conforming (submitting) to the default file structure of the eclipse/maven project- <classpathentry kind="src" output="target/classes" path="src/main/java">. I re-created the file structure (as this) put/copied my .java and .classes in those directories - it ran fine finally.
I could see this problem when I opened the .classpath file - it had the original /classes and /src directory and not he one I had edited in eclipse (as I indicated in my Question). Even though I was actually successfully compiling into my /classes.
I would certainly not expect this behavior, there is clear edit option for /src and /classes and it should take effect- but maybe not.
Another observation to add- when I look at my run configuration - I see the correct class but eclipse does not show the location. So one would never know.
So long story short it finally worked after much frustration and effort and loss of a couple of days (And I just had exactly one java file to compile and run - wondering how much pain would be if I had a few more).
I am not a regular eclipse user (any longer) so some of it would be getting used to etc - but some of these quarks need to be taken care of (It is the No1 tool)
My problem is best described with a screenshot:
As you can see, there is a org.virtuslab:unicorn-core_2.11 dependency loaded in my SBT/Scala project. The jar file with corresponding sources is available as well. For some reason, Intellij Idea decided to ignore the available source file Table.scala and uses the .class file instead. Clearly, all other files are okay.
Obviously, without the information contained in the .scala file, Intellij is not able to properly analyze my code and I'm getting Cannot resolve symbol BaseIdRepository errors (and similar) all over my project.
I manually checked the source package and the Table.scala file is there and seems alright. Plus this worked flawlessly until two days ago. I don't know why it broke down. I tried to revert my project using git to an earlier version when this was still working, but no luck.
I tried to both downgrade and upgrade the library, I tried to remove it and add it again, I tried create a completely new project based on existing sources, but once again, no luck.
Just for the record, I'm able to compile and run my project. The only thing that might be related is this warning that I get when compiling the project:
[warn] /home/tobik/scala/payola-viz/src/app/model/appgen/repository/UsersRepository.scala:7: Could not find any member to link for "BaseIdRepository".
I got an update for the Scala plugin which seems to fix this issue.
In case you experience similar problems, this temporary solution worked for me: I added the unicorn sources directly to my code base and manually removed it from the project libraries. I got rid of the errors and it still compiles as the library remains as a dependency inside built.sbt. To avoid polluting my project, I added the included sources to .gitignore. The workaround broke after a while but all I had to do was repeat the procedure again.
I would like to be able to automatically setup our eclipse projects to Ignore optional compile problems using m2e, but I seem to run into a conflict of m2e vs maven.
If I use the build-helper-maven-plugin to add source directories, it's great - I don't have to automatically add the generated-sources/annotations to my eclipse project. But if I do that, every time m2e Updates the eclipse project (alt+f5), it removes any manual configuration I've added to the source directores (including the Ignore optional compile problems).
So currently, my workaround is to manually add the generated-sources directories to the eclipse projects so that I don't constantly get all those warnings back on generated code.
(My use case is using dagger, which has a lot of generated code, but in very different formats from the rest of our code base, is not java8 based, etc, so we get lots of format and style warnings).
One answer may be to try out the Annotation Processing in m2e, but I've had issues with that in the past conflicting with maven on the command line and other issues, and I'm not sure it would address this issue anyhow. Even the choices in the list for Annotation Processing Mode both list the deficiencies.
Can anyone think of any other workarounds, until the bug is fixed?
The bug is finally fixed in M2E 1.6.2 (1.6.2/Mars RC2).
Introduction
I have spend a lot of time to fix this bug
In our application we have a lot of generated code by cxf and jaxb which produces tons of warnings. We use the maven-build-helper plugin to add this code to our projects automatically.
By adding this enhancement, eclipse JDT enabled the possibility to set the javac -nowarn flag for specific source folders. Unluckily, by updating the maven project the flag gets lost. There are a few threads on SO where users got bugged by bug.
What I have tried so far
So i came up with a clever solution, javac has a nowarn flag. I set it to my maven-compiler-plugin and specified the directory. My maven build was fine, but my eclipse build wasn't. My research told me, that eclipse jdt does only use the maven-compiler-plugin source and target version. So my next step was to try to configure the EclipseCompiler, but this is not possible, because there is no possibility to add custom compiler Arguments in eclipse JDT.
Next Step. Inside of the .classpath file, eclipse JDT adds an ignore_optional_problems attribute for each ignored path. By updating the maven project inside of eclipse, this entry gets lost. So i started to write a maven "ignore-source-folder" plugin which should add the missing attribute. To run the plugin each time eclipse starts a build, i also created a m2e connector to refresh the .classpath file and everything should be fine.
By testing my plugin with my connector i realized, it works, but only 70% of the repetitions.
What happened?
Every time eclipse m2e/Jdt starts a new build, all classpath entries will be removed and populated again. When my maven plugin gets triggered by eclipse, a race condition starts.
So I started to analyze the code of jdt and m2e jdt. The ignore_optional_problems flag gets only once set manually inside of the patch which was provided to JDT and isn't stored somewhere else. By triggering a new build via m2e-jdt this information gets lost.
How to fix this problem
To fix this problem, some element has to be added or extended in jdt which contains all ignored folders. If a new build gets triggered and the classpath file gets newly generated by m2e-jdt this element should be checked for ignored paths. ClasspathEntryDescriptor seems to be a good place for it.
My problem
I checked out jdt and m2e jdt, but i have tons of errors inside of my IDE and i have no idea how to start. And even if I fix the code, I have no idea how to build and test it. I think my effort will be to high and we talk about 20 or 30 simple lines of code.
I am afraid if I add my results to the filed bug at eclipse, no one will care about it.
So, is there any developer able and willing to help me for this tiny job?
You need to "fix" the M2E's JDT project configurator. Probably somewhere in the m2e-core project. So, your change should obtain some kind of configuration flag from the project pom and create corresponding classpath entries for JDT.
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.