I was searching for a way or tool to convert the regular expression into the ANTLR 4 expression but could not find anything suitable. Now i'm curious "Can we actually convert it or not." If not, then i assume ANTLR 4 expression and regular expression looks same look-wise but are totally different. Please correct if I'm wrong.
ANTLR lexer rules are actually regular expressions, in the formal sense. This means you won't get pattern matching features like lookahead/lookbehind/captures etc out of the box. You can insert custom code in the rules if you need more control over the matching process.
As for the syntax, it's a bit different from the standard regex syntax.
For instance, in ANTLR you write ~[a-z] instead of [^a-z]