getting user defined error messages using antlr3 - antlr

Question

numberrange returns [String value]
: numberrangesub
{
String numberRange = ($numberrangesub.text);
String [] v = numberRange.split(",");
if ( Integer.parseInt(v[0].trim()) < Integer.parseInt(v[1].trim())) $value =numberRange;
else throw new RecognitionException();
}
;
Please observe the above ANTLR code. In this I want to throw a user friendly error message like "from value should be less than to value in BETWEEN clause".
I am expecting like this RecognitionException("from value should be less than to value in BETWEEN clause"); But antlr did not accept like as above.
In java class where I am calling the generated java class by Antlr. I am handling like as follows.
try
{
parser.numberRangeCheck();
}
catch (RecognitionException e)
{
throw createException("Invalid Business logic syntax at " + parser.getErrorHeader(e) + ", " + parser.getErrorMessage(e, null), Level.INFO, logger);
}
Any help will be appriciated.

Answer 1

Why not simply throw a RuntimeException with your custom error message?
// ...
else throw new RuntimeException("from value should be less than to value in BETWEEN clause");
// ...

Answer 2

As Terrance wrote in "The Definitive ANTLR Reference" error chapter excerpt:
To avoid forcing English-only error messages and to generally make
things as flexible as possible, the recognizer does not create exception
objects with string messages. Instead, it tracks the information necessary to generate an error.
So there is no error message supplied to RecognitionError's constructor. But you can define additional field of your recognizer to hold user-friendly error message shown on RecognitionError handling:
numberrange returns [String value]
: numberrangesub
{
String numberRange = ($numberrangesub.text);
String [] v = numberRange.split(",");
if ( Integer.parseInt(v[0].trim()) < Integer.parseInt(v[1].trim()))
$value = numberRange;
else {
this.errorMessage = "from value should be less than to value in BETWEEN clause";
throw new RecognitionException(this.input);
}
}
;
And then override the getErrorMessage method:
public String getErrorMessage(RecognitionException e, String[] tokenNames) {
String msg = this.errorMessage;
// ...
}
This works similar to paraphrase mechanism explained in the same excerpt.