diff --git a/runtime/Java/doxyfile b/runtime/Java/doxyfile
index a589fd6c7..c66ff9966 100644
--- a/runtime/Java/doxyfile
+++ b/runtime/Java/doxyfile
@@ -216,7 +216,7 @@ HAVE_DOT               = YES
 CLASS_GRAPH            = YES
 COLLABORATION_GRAPH    = YES
 GROUP_GRAPHS           = YES
-UML_LOOK               = NO
+UML_LOOK               = YES
 TEMPLATE_RELATIONS     = NO
 INCLUDE_GRAPH          = YES
 INCLUDED_BY_GRAPH      = YES
diff --git a/runtime/Java/src/org/antlr/v4/runtime/TokenStream.java b/runtime/Java/src/org/antlr/v4/runtime/TokenStream.java
index 5acfd96f0..e643535bd 100644
--- a/runtime/Java/src/org/antlr/v4/runtime/TokenStream.java
+++ b/runtime/Java/src/org/antlr/v4/runtime/TokenStream.java
@@ -35,7 +35,7 @@ import org.antlr.v4.runtime.misc.Interval;
 public interface TokenStream extends IntStream {
     /** Get Token at current input pointer + i ahead where i=1 is next Token.
 	 *  i<0 indicates tokens in the past.  So -1 is previous token and -2 is
-	 *  two tokens ago. LT(0) is undefined.  For i>=n, return Token.EOFToken.
+	 *  two tokens ago. LT(0) is undefined.  For i>=n, return eof token.
 	 *  Return null for LT(0) and any index that results in an absolute address
 	 *  that is negative.
      *  TODO (Sam): Throw exception for invalid k?
diff --git a/tool/playground/ExtractInheritance.java b/tool/playground/ExtractInheritance.java
new file mode 100644
index 000000000..29d97b1c9
--- /dev/null
+++ b/tool/playground/ExtractInheritance.java
@@ -0,0 +1,54 @@
+import org.antlr.v4.runtime.Token;
+import org.antlr.v4.runtime.tree.TerminalNode;
+
+import java.util.List;
+
+public class ExtractInheritance extends JavaLRBaseListener {
+	JavaLRParser parser;
+	public ExtractInheritance(JavaLRParser parser) { this.parser = parser; }
+
+	/*
+	normalClassDeclaration
+	    :   'class' Identifier typeParameters?
+	        ('extends' type)?
+	        ('implements' typeList)?
+	        classBody
+	    ;
+
+	 */
+	@Override
+	public void enterNormalClassDeclaration(JavaLRParser.NormalClassDeclarationContext ctx) {
+		TerminalNode<Token> id = ctx.Identifier();
+		String sup = null;
+		if ( ctx.type()!=null ) {
+			sup = ctx.type().getText();
+			System.out.println("\""+id+"\" -> \""+sup+"\"");
+		}
+		if ( ctx.typeList()!=null ) {
+			List<? extends JavaLRParser.TypeContext> type = ctx.typeList().type();
+			for (JavaLRParser.TypeContext t : type) {
+				System.out.println("\""+id+"\" -> \""+t.getText()+"\"");
+			}
+		}
+	}
+
+	/*
+	normalInterfaceDeclaration
+	    :   'interface' Identifier typeParameters? ('extends' typeList)? interfaceBody
+	    ;
+
+	 */
+
+	@Override
+	public void enterNormalInterfaceDeclaration(JavaLRParser.NormalInterfaceDeclarationContext ctx) {
+		TerminalNode<Token> id = ctx.Identifier();
+		System.out.println("###### interface "+id);
+		String args = null;
+		if ( ctx.typeList()!=null ) {
+			List<? extends JavaLRParser.TypeContext> type = ctx.typeList().type();
+			for (JavaLRParser.TypeContext t : type) {
+				System.out.println("\""+id+"\" -> \""+t.getText()+"\"");
+			}
+		}
+	}
+}
diff --git a/tool/playground/GenHierarchy.java b/tool/playground/GenHierarchy.java
new file mode 100644
index 000000000..19222574f
--- /dev/null
+++ b/tool/playground/GenHierarchy.java
@@ -0,0 +1,61 @@
+import org.antlr.v4.runtime.ANTLRInputStream;
+import org.antlr.v4.runtime.CommonTokenStream;
+import org.antlr.v4.runtime.ParserRuleContext;
+import org.antlr.v4.runtime.Token;
+import org.antlr.v4.runtime.tree.ParseTreeWalker;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+
+public class GenHierarchy {
+	public static void main(String[] args) throws Exception {
+		// START: input
+		String inputFile = null;
+		if ( args.length>0 ) inputFile = args[0];
+		List<String> files = getFilenames(new File(inputFile));
+		for (String file : files) {
+			InputStream is = new FileInputStream(file);
+			ANTLRInputStream input = new ANTLRInputStream(is);
+			// END: input
+
+//			System.out.println(file);
+			// START: launch
+			JavaLRLexer lexer = new JavaLRLexer(input);
+			CommonTokenStream tokens = new CommonTokenStream(lexer);
+			JavaLRParser parser = new JavaLRParser(tokens);
+			ParserRuleContext<Token> tree = parser.compilationUnit(); // parse
+
+			ParseTreeWalker walker = new ParseTreeWalker(); // create standard walker
+			ExtractInheritance extractor = new ExtractInheritance(parser);
+			walker.walk(extractor, tree); // initiate walk of tree with listener
+		}
+		// END: launch
+	}
+
+	public static List<String> getFilenames(File f) throws Exception {
+		List<String> files = new ArrayList<String>();
+		getFilenames_(f, files);
+		return files;
+	}
+
+	public static void getFilenames_(File f, List<String> files) throws Exception {
+		// If this is a directory, walk each file/dir in that directory
+		if (f.isDirectory()) {
+			String flist[] = f.list();
+			for(int i=0; i < flist.length; i++) {
+				getFilenames_(new File(f, flist[i]), files);
+			}
+		}
+
+		// otherwise, if this is a java file, parse it!
+		else if ( ((f.getName().length()>5) &&
+			f.getName().substring(f.getName().length()-5).equals(".java")) )
+		{
+			files.add(f.getAbsolutePath());
+		}
+	}
+
+}
diff --git a/tool/src/org/antlr/v4/automata/ATNSerializer.java b/tool/src/org/antlr/v4/automata/ATNSerializer.java
index a04fb2018..bc809efe4 100644
--- a/tool/src/org/antlr/v4/automata/ATNSerializer.java
+++ b/tool/src/org/antlr/v4/automata/ATNSerializer.java
@@ -36,6 +36,7 @@ import org.antlr.v4.runtime.atn.ATNSimulator;
 import org.antlr.v4.runtime.atn.ATNState;
 import org.antlr.v4.runtime.atn.ActionTransition;
 import org.antlr.v4.runtime.atn.AtomTransition;
+import org.antlr.v4.runtime.atn.BlockStartState;
 import org.antlr.v4.runtime.atn.DecisionState;
 import org.antlr.v4.runtime.atn.LoopEndState;
 import org.antlr.v4.runtime.atn.PredicateTransition;