I am doing the Scala introductory course from Coursera.
Within Intellij, I am trying to debug but breakpoints are ignored.
Unlike in this question: Can't debug a Scala application in IntelliJ + sbt-idea-plugin, I am not getting any error.
Do I need to install something or set some Intellij configurations?
Someone recently walked me through debugging in InteliJ using scala/scalatest. I am running InteliJ Idea 2017.2 with the latest scala language plugin installed, no SBT plugin installed (as far as I can tell this is just part of the scala plugin now). Hopefully this helps some other people out:
Set breakpoints by clicking next to the line number you want to test.
Assuming you are using ScalaTest to set up some conditions and run your program, you can right-click on one of your test classes, and then select Debug '[classname]' from the dropdown. This should pop open the debug pane on the bottom.
When you use InteliJ to run the debugging directly (not attaching through sbt etc) I was actually able to get this to work. I have not had success with any of the answers to related questions that discuss attaching to a running sbt process (with scalatest at least).
There are a lot of useful things that intelij debug gives you with scalatest at this point. Say there is one test that is failing and you want to dig into why. On the debug window, click the console tab, and you will see a list of your tests ordered by suite w/ red marks next to the ones that failed. You can right-click on a single test and select debug from the dropdown to only debug that one test. It's pretty useful.
Hopefully that helps some other people! I also hit a few gotchas I should outline:
Sometimes I need to re-load the sbt project (click the circular arrow thing under the sbt project tab on the left). It takes a while but it cleans up some random errors about classes not being found, and even unrelated sounding things like One or more requested classes are not Suites.
I sometimes get errors about shaded classes not found, especially when using docker through sbt (for example to spin up a db node in my tests). To get around that I first deleted the cached compiled jar (rm -r $HOME/.ivy2/cache/com.spotify/ for example to get rid of the cached compiled code that was causing problems) then I reloaded the project as in step-1.
If all else fails, make sure that the project is properly imported. You might need to delete the .idea folder in your folder and re-import the sbt project. This trashes your settings and all, but it's worked for me as a last resort in the past.
Related
Okay. So i ahve this problem concerning itelliJ revolving around SBT and Scala.
The problem is that intelliJ cannot correctly import the project, and i am left with an intelliJ that recognizes only false syntax errors and which cant compile from the "run" bottom integrated within the IDEA.
When I start IntelliJ/Open the project, the SBT goes to work and tries to index the project, after which it fails, returning me multiple errors.
Extracting structure failed: Structure file /tmp/sbt-structure.xml is empty
Picture of additional erros
The thing is, that the code works, using the terminal it can both compile and run!
I feel like i have traversed the internet and done multiple things including:
Reload SBT.
Try to Import the project with SBT.
Reinstall plugins.
Restart and invalidate cahces.
Thanks in advance!
I don't understand exactly what is the way of working with maven projects in Eclipse.
The problems I have are often with projects I download from github. If I set the project myself it usually work, so I think I'm doing something different from the majority of people.
I'll try to detail a specific case:
I clone a repo, let's say: https://github.com/spring-guides/tut-spring-boot-oauth2
In Eclipse I import "existing maven project"
The project has a "Maven nature" as indicated by M on the folder icon
I try to run java class with main from Eclipse. First strange thins is that the "Run As" menu doesn't have "Run as a Java application"
I have to configure the configuration manually. Now it runs, but strange things happens, like I can't edit the file as the "content assist" throw errors instead of giving the normal assists.
I notice that the project has no "source folder". So my first instinct is to add a Java nature or select src as source folder
So I add Java nature to the project. This is a disaster. It can compile anymore as it can find packages. All classes have errors. I try to play around setting source folders on /src or /src/main/java. Sometimes I fix the errors but I can't run (and now I have run as Java application) but when I run it can't load the class
So in the end, I'm a bit confused and I don't know if I explained clearly what I'm doing.
I think I would like to know in a simple way how people are doing it, rather than trying to correct my steps as I'm probably creating a mess myself.
Any help or suggestion welcome.
I'm using the last version of eclipse. I don't know which other tool's versions are relevant.
P.S. I also refresh,restart,clean rebuild the project often after touching things...but it doesn't get better
Maven is a build (management) tool. Simply spoken, its task is to create a JAR that can be used as a dependency/library by other projects or when running java -jar ....
Running a project's code isn't part of it (apart from unit and integration tests code and by using non-default plugins for special situations). Running code is part of Eclipse (or any other IDE) with its Run Configurations.
If I run my application (Play 2.3.2) while Eclipse is running I always have strange compilation errors, no class def found errors, class not found errors, etc...
If I exit Eclipse and run my application, everything is working fine. But sometimes it's also working fine while Eclipse is running.
Am I the only one to experience that ? What is the cause ?
I suspect something in Eclipse changes my source files but I can't find what.
Maybe Lombok ?
Thanks.
I have similar problems. Typesafe responded with a solution which I am currently trying out.
https://groups.google.com/forum/#!topic/play-framework/4RnbqEk-muM
Brief summary of the answer by #jroper :
Eclipse doesn't know
how to keep its dirty hands off the same build directory that Play is
using to compile your app - if you have both Play, and the IDE, trying
to compile the same code at the same time, what do you think will
happen? You will see random errors. You should configure Eclipse not
to automatically build your app, or configure it to have different
output directories.
The Play Framework compiles everything to the directory target/scala-2.11/classes. When changing some of these classes, especially any views, causes Activator to auto compile the classes creating new class files. Hitting refresh on the project in Eclipse will update the project and class files in the classes directory causing a rebuild. This should make your compilation errors go away. If you still have issues, take a look at your .classpath file and the Eclipse build path settings.
I have recently completed the Scala course on Coursera, and since then I have been looking forward to getting my hands dirty with Scala again. I have written code for some years but I neither educated to be nor work as a programmer, so it took me a while to get a good opportunity but now that I have some time to invest and a good project to work on it's time...
Except I can't seem to get things set up properly, which I find really frustrating. I have OpenJDK 1.7.0_25 running on my Linux machine. I have downloaded and installed the Bundle Scala IDE build for Eclipse (just like we used in the course). And I got ScalaTest both as a jar file and the Eclipse plug-in.
I have a simple project (so far) and no matter what I do I can't seem to get my builds and tests in order. First off how exactly am I supposed to set up my project so that my classes and tests are actually run properly? All the assignments we got were projects that had the same structure, so do I have to have:
project
|--src
|--main
|--scala
|--test
|--scala
structure? If so why is it not the default way the project is setup when I create a new project? Do I create these folders manually, as packages or as source folders? The whole thing gets pretty murky..
I should mention that I tried to "Mavenize" the project using the contextual menu in Eclipse, added my ScalaTest dependency. The first thing that happens is that I get compile errors, at every point of dependency in my code. So clearly the library is not visible, in other words Maven does not seem to be doing much of management. I thought the whole point of Maven was to get and maintain dependencies as the project evolves. I concluded that I do not fully understand the way Maven works and thus I eventually gave up on Maven, once again, and went back to doing things manually.
Secondly, I can't seem to run my tests; the Run As... menu item does not include ScalaTest as it's mentioned in the documentation of ScalaTest Eclipse Plug-in. I have double checked that the plugin is installed. If I instead try to run using JUnitRunner then my tests are not recognized as valid tests. I have JUnit and ScalaTest on my build path, so it's got to be something else.
I suppose my overarching question is as follows:
given the Scala IDE build of Eclipse and ScalaTest, just exactly how am I supposed to set up my project (in Eclipse) so that I can just focus on writing my code and testing it, and hopefully not have any other headaches?
I work alone, and this project is not a product I need to deliver to some client. In other words I do not need to adhere to strict professionalism here. Honestly I just want to be able to code, get better acquainted with Scala and hopefully build a small data analysis tool that I will be using from time to time.
Thanks in advance!
Try using the sbt eclipse plugin:
https://github.com/typesafehub/sbteclipse
This is of course assumes that you use sbt as you build tool. If you don't at the moment you can find instructions on installation and usage here: http://www.scala-sbt.org/
Personally I've been using typesafe giter8 template (https://github.com/typesafehub/scala-sbt.g8) to setup my Scala projects, and then I use the sbt plugin mentioned above to generate eclipse project files.
Scala is somewhat Maven-based (sometimes implicitly), that's why you use that structure.
The easiest way I think is to create a simple Sbt/Maven POM and create the Eclipse project configurations (like with sbt eclipse). There you can set the dependencies (like the actual version of JUnit, Scalatest to use), so you can use the ScalaTest plugin easily.
In case of other issues, feel free to ask at the ScalaTest mailing list, Chee Seng and Bill Venners can help you a lot there.
The Scala IDE website has a full documentation on how to run unit testing frameworks with the IDE, have a look ! If you find missing elements, the bug tracker of the scala-IDE project is here.
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.