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 am trying to set a breakpoint in a Scala Macro implementation using the Eclipse IDE and failing
Firstly: Scala Macros Rock! Up to now I have preferred Clojure to Scala, but with macros I'm no longer sure
I'm trying to create a macro that will return the toString of a function and the function itself. When that works I'm going to make a new function with a sensible toString. Ah happy days.
But I need to be able to debug the macros. I use Eclipse (20110615-0604), with Scala (2.10.1). I downloaded the scala-compiler-2.10.1.jar and the code from http://www.warski.org/blog/2012/12/starting-with-scala-macros-a-short-tutorial/ now works. I've written a couple of simple macros as well. The macros are in an eclipse project "ScalaMacro" and the code that uses them is in a separate project "HelloScalaMacro"
I'd now like to debug them
Following the instructions at http://docs.scala-lang.org/overviews/macros/overview.html I have created a runtime configuration with scala.tools.nsc.Main as the entry point. I've added -cp HelloScala.scala, and when I run the configuration it actually seems to compile the code (if I put errors in, it reports the errors correctly).
Unfortunately the instructions imply that a breakpoint in the macro implementation should cause Eclipse to pause. It doesn't.
I've done the usual: google search for Eclipse/Scala macro/Debug/Breakpoint, read all the stackoverflow questions in the scala-macro tag, and played around a lot with every eclipse setting I can find.
So if any of you out there know how to set breakpoints, could you let me know how: is it an eclipse version / scala version / ... issue?
I haven't tried this myself, and in principle it is as likely (or more likely) to fail as what you've already tried, but if successful it could be more convenient to you.
To try this you should have Scala-IDE along with the source feature installed. Make sure you are working off of an Eclipse installation that is either "Eclipse Classic", "Eclipse for RCP Developers", or a similar concoction you came up with on your own.
You will also want to install the Equinox Weaving Launcher plugin, that will allow you to create an "Eclipse Application with Equinox Weaving" launchers.
Now:
Create a new workspace
Create a Scala project
Plant your macro code in that project
Add a break point in the macro source
Getting ready to debug:
Create a new "Eclipse Application with Equinox Weaving" debug launch configuration. Give a name more elegant than "New_configuration".
under "location", point it towards a new different workspace directory
under the "configuration" tab, provide something like "-Xmx1536m"
By default, all plugins available to your running Eclipse instance should be available to the instance you are about to launch. Eclipse may need some cajoling in order to include a non-plugin project in the classpath -- if this doesn't work, that's the first thing I'd try to look at.
You will now want to launch the debug configuration.
Depending on your Scala-IDE version, you may encounter a "Multiple launchers available -- Select one..." warning. I'd go for "Equinox Weaving enabled Eclipse Application Launcher".
Once inside the Eclipse instance being debugged:
Create the project you want to use the macro
Make sure to add a dependency on the binary output
Add a small usage example of your macro to the project in the workspace being debugged.
Cross your fingers
Build
In theory, the launching Eclipse instance will now pause the instance being debugged on your break point.
The instructions given by Nadavwr (just below) were helpful, and I recommend them to other people.
The key solution for me was to realise that there are two projects involved, the project that defines the macro, and the project that uses the macro. Rather foolishly I was trying to debug the project that defined the macro
So the instructions as given in the documentation are correct, I just had to make sure I was running them in the correct project: obvious of course.
For the benefit of other people, I found it very helpful to use a command line scalac to get the command line correct: much quicker editing that, and controlling which directory I was in, then in eclipse
The other thing to realise for people thinking of using Scala Macros are that the error messages from running scalac directly are MUCH better than those from eclipse.
I am already using an open source GWT project (iServe) and I would like to integrate into it another open source GWT project (PetalsBPM), by which I mean being able to call it and reference its methods.
I have imported iServe in Eclipse (it has multiple modules) as separate Maven projects referencing its other and can run it successfully through Runas -> Web application in development mode.
If I do that and run the other project through the console as mvn gwt:run, I call initiate PetalsMBP through iServe. However, that means that the two programs have to run as is, without communication with each other.
I have also imported the second project into eclipse as a java project successfully (converting into a Maven one causes problems - various lifecycle configurations ones), but whenever I try to add to to iServe through Properties -> Java Build Path -> Projects, although it does not cause any errors immediately, I cannot launch iServe anymore. It produces the following error:
"Exception occurred executing command line.
Cannot run program "C:\Program Files\Java\jre7\bin\javaw.exe" (in directory "C:...iserve-sal-gwt-1.0.0-SNAPSHOT"): CreateProcess error=206, The filename or extension is too long"
Are my problems related to the fact that PetalsBPM is not a Maven project in Eclipse (I doubt it)?
Am I doing something wrong, i.e., this is not the way to reference a project from another one? should I add a reference to the first project's (iServe) gwt.xml file?
Is there a way to do what I want without having to wrap the second project as a jar and calling it from iServe? I would prefer not to, since producing a jar every time I make a slight change is not exactly efficient!
P.S: The second project is a regular GWT project with an entrypoint, not just a module. Should I remove this?
UPDATE: Trying to figure out the source of this error, I attempted to simplify the problem, so I performed the following moves:
I created two new simple GWT projects and tried to reference one
from the other. Worked fine
I referenced the project I actually want
to use (PetalsBPM) from the simple one I just created. Also works
fine.
I referenced the new simple project from the original one I
want to use (iServe). Also works fine.
Tried doing what I actually
want to do, copying the settings from 2&3. Produces the same error
"CreateProcess error=206, The filename or extension is too long" if
I reference PetalsBPM (does not when I remove it from the referenced
projects)
So, I tried switching workspaces. I created a new workspace in C:\, and moved the actual projects there. Still it did not work. :(
Any more ideas?
I met the same type of error "Create Process, error=206, path too long etc." a hundred times.
Then, I found a solution/explanation in google-groups, it solved my problem.
I post the content and link as it might help others.
This website (StackOverflow) really helped me a thousand times.
Thanks to you all !
solution/explanation :
(Response from Stephen Johnson)
(...) if you're using eclipse plugin go to Project | Properties, choose
Google \ App Engine \ ORM and only include directories that you have
classes that you want enhanced. By default it does the entire project
so that includes a lot of needless files. (...)
Link :
original post # google-groups
Read the exception message again. Somewhere along the way Maven is generating a path that is too long for (some) Windows API to handle, try moving your workspace to a directory straight below C:\.
I just tried "skolima" reply and it worked for me. In Eclipse I clicked File->Switch Workspace.
Three things to note:
After I created the workspace in "C:\workspace" I had to update my Project->Properties > Java Build Path > Libraries > Add External JARs...
I'm using Windows 7.
I'm using "Eclipse Java EE IDE for Web Developers"
I hope this others.
Is there way to tell IntelliJ IDEA which output folder to use for GWT compiler ? I know it copies artifacts to project folder but it doesn't copy extras which I set using "-extra" command line parameter of gwt compiler.
IntelliJ IDEA leaves it in USER_HOME/.IntelliJIdea10/system/gwt/project_name_with_hash/module_name_with_hash/compile/www
UPDATE: Strangely I didn't find list of possible path macroses on IntelliJ's website. But I found them in idea.jar. Possible macroses are:
APPLICATION_HOME_DIR
PROJECT_DIR
MODULE_DIR
USER_HOME
Have you tried constructing the path using ${PROJECT_DIR} path variable? That will resolve to the project location and then you can specify the rest of the path. Like ${PROJECT_DIR}/reports/extras. I haven't used IntelliJ for a few years, but I am pretty sure that's the path variable name.
EDIT: sorry built in path macros in IntelliJ are specified using $...$ syntax. So I think it should be $PROJECT_DIR$
There is no way to change output folder for GWT compiler in IDEA. However you can specify absolute path to any directory after '-extra' parameter.
By the way for what purpose do you use '-extra'?
As of November 18, 2011 it is impossible to use path macroses in settings of project modules. Jetbrain is aware of this and there is feature request in their JIRA.
My work-around for a team with multiple engineers for now is to use system TEMP folder for GWT compiler extra output and move files in post-build event to folder I want it to be at.