Extract abstract method in Recognizer for Parser.getGrammarFileName() and generated lexer's getGrammarFileName(). Make Recognizer.getTokenNames(), getRuleNames(), and getATN() abstract - implementations are always generated.

runtime/Java/src/org/antlr/v4/runtime/Parser.java

@@ -476,13 +476,6 @@ public abstract class Parser extends Recognizer<Token, ParserATNSimulator<Token>
 		return stack;
 	}
 
-	/** For debugging and other purposes, might want the grammar name.
-	 *  Have ANTLR generate an implementation for this method.
-	 */
-	public String getGrammarFileName() {
-		return null;
-	}
-
     /** For debugging and other purposes */
     public List<String> getDFAStrings() {
         List<String> s = new ArrayList<String>();

runtime/Java/src/org/antlr/v4/runtime/Recognizer.java

@@ -53,15 +53,16 @@ public abstract class Recognizer<Symbol, ATNInterpreter extends ATNSimulator> {
 	 *  error reporting.  The generated parsers implement a method
 	 *  that overrides this to point to their String[] tokenNames.
 	 */
-	public String[] getTokenNames() {
-		return null;
-	}
+	public abstract String[] getTokenNames();
 
-	public String[] getRuleNames() {
-		return null;
-	}
+	public abstract String[] getRuleNames();
 
-	public ATN getATN() { return null; }
+	/** For debugging and other purposes, might want the grammar name.
+	 *  Have ANTLR generate an implementation for this method.
+	 */
+	public abstract String getGrammarFileName();
+
+	public abstract ATN getATN();
 
 	public ATNInterpreter getInterpreter() { return _interp; }
 

tool/resources/org/antlr/v4/tool/templates/codegen/Java/Java.stg

@@ -723,6 +723,7 @@ public class <lexer.name> extends Lexer {
 		_interp = new LexerATNSimulator(this,_ATN);
 	}
 
+	@Override
 	public String getGrammarFileName() { return "<lexer.grammarFileName>"; }
 
 	@Override

tool/src/org/antlr/v4/tool/interp/ParserInterpreter.java

@@ -45,6 +45,11 @@ public class ParserInterpreter {
 			this.g = g;
 		}
 
+		@Override
+		public String getGrammarFileName() {
+			return null;
+		}
+
 		@Override
 		public String[] getRuleNames() {
 			return g.rules.keySet().toArray(new String[g.rules.size()]);
@@ -54,6 +59,11 @@ public class ParserInterpreter {
 		public String[] getTokenNames() {
 			return g.getTokenNames();
 		}
+
+		@Override
+		public ATN getATN() {
+			return null;
+		}
 	}
 
 	protected Grammar g;