ANTLR4 Generating Lexer in JAVA instead of C Sharp - antlr4

Question

When doing
java -cp C:\Tools\Libraries\antlr4-csharp-complete.jar org.antlr.v4.Tool Hello.g4
I get the following files:
HelloBaseListener.cs
Hello.tokens
HelloListener.cs
HelloParser.cs
HelloLexer.tokens
HelloLexer.java
My question is about the last file. Why is it .java instead of .cs?
I'm using antlr4-csharp-4.0.1-SNAPSHOT-complete.jar
Grammar is:
grammar Hello; // Define a grammar called Hello
options
{
language=CSharp_v4_0;
}
r : 'hello' ID ; // match keyword hello followed by an identifier
ID : [a-z]+ ; // match lower-case identifiers
WS : [ \t\r\n]+ -> skip ; // skip spaces, tabs, newlines, \r (Windows)
Hello Sam! I only have visual studio express so I can't install the extension. This is the code that I'm using but it is still generating the HelloLexer.java.
AntlrClassGenerationTaskInternal a = new AntlrClassGenerationTaskInternal();
List<String> files = new List<string>();
files.Add(#"C:\Tools\Grammars\Hello.g4");
a.JavaVendor = "JavaSoft";
a.ToolPath = #"C:\Tools\Libraries\antlr4-csharp-complete.jar";
a.JavaInstallation = "Java Development Kit";
a.SourceCodeFiles = files;
a.OutputPath = #"C:\Tools\Grammars\CSharp\";
a.Execute();
By the way, visual studio complained because it was not able to find Antlr4ClassGenerationTask.IsFatalException(ex)
I appreciate your help on this.
Regards,
Omar.

Answer 1

I think it's a bug, I had got the same problem, but there is a solution.
1) If you want you can remove
options
{
language=CSharp_v4_0;
}
I think is ignored by the code generator
2) create a BAT file with the follow code
#echo OFF
IF "%CLASSPATH%" == "" (SET CLASSPATH=.;.\antlr4-csharp-4.0.1-SNAPSHOT-complete.jar;%CLASSPATH%)
java org.antlr.v4.Tool %* -Dlanguage=CSharp_v4_5
put antlr4-csharp-4.0.1-SNAPSHOT-complete.jar in the same path, now you can use this file to comile. To resolve the issue the magic command line argument is "-Dlanguage=CSharp_v4_5" or the version of C# you are using.
The generated files now have inside the Lexer.cs

Answer 2

Edit 11/20/13: Updated instructions are now available on the project wiki
https://github.com/sharwell/antlr4cs/wiki/Installation
Here are a few messages I sent over the past few months related to this issue. If you don't want to install the Visual Studio extension described below, you'll need to use the source code of Antlr4ClassGenerationTaskInternal.cs to determine a set of command line options that will work.
Also, you can remove the language=CSharp_v4_0; option because it's passed on the command line now.
The C# target wasn't designed for command line usage. You will need to integrate the code generation into your project file according to the instructions on the following page, and the parsers will be generated automatically when you build your project.
https://github.com/sharwell/antlr4cs
You do need to include the .g4 file in your project and configure a few properties of the file. If you install the following extension before adding the grammar to your project, all the other options will be configured for you automatically.
ANTLR Language Support for Visual Studio 2010-
2012
If you already have the .g4 file in your project, and want to still use the extension to automatically configure the proper settings, you can do the following:
Install the extension.
Click the project in Solution Explorer and enable Show All Files (button on the Solution Explorer toolbar). This step greatly simplifies step 4.
Right click the .g4 file in the project, and select Exclude From Project.
Right click the .g4 file again and select Include In Project.
(Optional) You can disable Show All Files when you no longer need it.