Intellij will not recognize antlr generated source code - intellij-idea

Question

I am having trouble getting Intellij to recognize the generated source code from antlr4. Any reference to the generated code appears as errors, code completion doesn't work, etc.
I am using maven and the antlr4-maven-plugin to generate the code.
My code, referencing the generated code compiles and builds fine under maven.
The generated code is under /target/generated-sources/antlr4, which is what Intellij expects.
I have tried the usual fixes such as reimport maven projects, update folders, invalidate cache, etc. None of it seems to work.
Anyone seen this before?
Is there a way to point to the generated sources directly within Intellij?

Answer 1

The problem
target/generated-sources/antlr4 is not automatically marked as source dir, instead its direct subdir com.example is. Intellij Idea fails to detect proper package for classes inside target/generated-sources/antlr4/com.example.
The cause
The source file *.g4 is in src/main/antlr4/com.example, but it actually it should be src/main/antlr4/com/example. Note the /. You probably forgot to mark src/main/antlr4 as source dir in Idea, and when you thought you are creating package structure, you actually just created single dir called com.example.
The fix
Mark src/main/antlr4 as source dir, create proper directory structure src/main/antlr4/com/example. Rebuild.
Alternative fix
Go to Project Structure - Modules - Source Folders and find the target/generated-sources/antlr4/com.example - click Edit properties and set Package prefix to com.example.
Different but related problem here

Answer 2

My issue was somewhat similar to #spilymp's:
I was putting the *.g4 files directly in src/main/antlr4:
.
├── src/
| └── main/
| ├── antlr/
| | ├── Main.g4
| | └── imported.g4
| └── java/
| └── com/
| └── test/
| └── Test.java
which led to source being generated in default package. I changed the package structure to match that of java:
.
├── src/
| └── main/
| ├── antlr/
| | ├── com/
| | | └── test/
| | | └── Main.g4
| | └── imports/
| | └── imported.g4
| └── java/
| └── com/
| └── test/
| └── Test.java
(Note that imports need to go directly in src/main/antlr4/imports)
After this I just run the antlr4 goal from the maven menu ([Module] > Plugins > antlr4 > antlr4:antlr4), which generated the sources in the default location (target/generated-sources/antlr4), where they were already marked with blue, generated-sources icon by Intellij, and MainParser can now be imported!

Answer 3

It turns out that my fiddling with preferences caused this issue. If anyone else has this problem:
As v0rl0n mentioned, first make sure the gen folder is listed as a source. Go to Module Settings -> Modules -> Sources.
Look to the right for the blue Source Folders. Ensure your generated source folders are listed (they should have a [generated] flag on the row).
If your generated source directory is listed there, and they are still not being recognized, go to Preferences -> File Types. Look in the Ignore files and folders field. Make sure you don't have anything listed that will match for your generated sources directory.
In my case, I had added target to this list, which caused my problem, and was a real pain to find.

Answer 4

I had what I think may have been a similar issue. I am new to IntelliJ, so I am guessing to some extent.
Is the gen folder in your project brown (i.e. a resource) or blue (source code)?
I could not get my project to recognize generated code until I managed to get the gen folder registered as one containing source code.
Sorry to say you may need to fiddle with it - I cannot recall how I did it - but all was well after I changed this.

Answer 5

Steps that worked for me:
Open Maven Projects in right tab
Right click on the module that contained my antlr code
Click Generate Source and Update Folders

Answer 6

I had a similar problem. Intellij found my generated code in the java folder but not in a subfolder of java. I solved it by putting my grammar files (*.g4) into a package (com.test):
.
├── src/
| └── main/
| ├── antlr/
| | └── com.test/
| | └── Test.g4
| └── java/
| └── test/
| └── Test.java
└── target/
└── generated-sources/
└── antlr/
└── com.test/
├── TestBaseListener.java
└── ...

Answer 7

The easiest way to solve this issue is to Right-Click the gen directory and choose Mark Directory as -> Sources Root