ANTLR4 Error "Problems calling org.antlr.v4.gui.TestRig.main" - antlr4

Question

Hello I get this error when I try the simple esample of the tutorial:
"grun Hello -r tree
Warning: TestRig moved to org.antlr.v4.gui.TestRig; calling automatically
Problems calling org.antlr.v4.gui.TestRig.main(args)
"
I cannot figure out what is going on.
Can you help me please.

Answer 1

It sounds like you have setup your 'grun' alias to use :
org.antlrv4.runtime.misc.TestRig
//and from antlr4 onwards they deprecated that and use this instead.
org.antlrv4.gui.TestRig
So you should try resetting your 'grun' alias either from terminal or batch file depending on how you set it up. If there are still errors comment here and i will try and help:
alias grun='java org.antlr.v4.gui.TestRig'
if you still have any errors after updating your setup alias then leave a comment and i will try to help further.

Answer 2

Setup TestRig - Added here so content is not lost after the documentation section is shut down.
ANTLR contains a testing tool in its runtime library, this tool can be used to display information detailing how the parsing is performed to match input against defined rules in your grammar file.
To use this tool contained within the ANTLR jar file you should setup your systems classpath to allow access to both the ANTLR tool and the runtime library :
export CLASSPATH=".:/usr/local/lib/antlr-4.5.3-complete.jar:$CLASSPATH"
Note: Ensure the Dot precedes any path to ensure the java virtual machine wont see classes in your current working directory.
Alises can be used on Linux/MAC/Unix to simplify commands used:
alias antlr4='java -jar /usr/local/lib/antlr-4.5.3-complete.jar'
//or any directory where your jar is located
Note setup on windows for aliases and classpath setup may be more complicated, see here for more comprehensive details.
Accessing TestRig
Once you have setup your alias you can setup TestRig in the following way, again using an alias is recommended as reduces the amount of time required to perform the action:
alias grun='java org.v4.runtime.misc.TestRig'
If you do not wish to setup an alias on windows you can access TestRig by running the following command in the same location as your ANTLR jar directory:
java -cp .;antlr.4.5.3-complete.jar org.antlrv4.runtime.misc.TestRig
//or
java -cp .;antlr.4.5.3-complete.jar org.antlrv4.gui.TestRig
To run TestRig on your grammar you can pass the parameters in for your grammar like this :
grun yourGrammar yourRule -tree //using the setup alias java -cp .;antlr.4.5.3-complete.jar org.antlrv4.gui.TestRig yourGrammar YourRule -tree //on windows with no alias java -cp .;antlr.4.5.3-complete.jar org.antlrv4.gui.TestRig yourGrammar Hello r -tree //Windows with the grammar Hello.g4 starting from the rule 'r'.
grun yourGrammar yourRule -tree //using the setup alias
java -cp .;antlr.4.5.3-complete.jar org.antlrv4.gui.TestRig yourGrammar YourRule -tree //on windows with no alias
java -cp .;antlr.4.5.3-complete.jar org.antlrv4.gui.TestRig yourGrammar Hello r -tree
//Windows with the grammar Hello.g4 starting from the rule 'r'.