diff -r 77f7135b6eb1 -r 3ee23267706c javap/src/main/java/org/apidesign/javap/StackMapTableData.java
--- a/javap/src/main/java/org/apidesign/javap/StackMapTableData.java	Fri Nov 16 08:08:36 2012 +0100
+++ b/javap/src/main/java/org/apidesign/javap/StackMapTableData.java	Thu Nov 29 20:19:00 2012 +0100
@@ -32,7 +32,7 @@
 
 /* represents one entry of StackMapTable attribute
  */
-class StackMapTableData {
+abstract class StackMapTableData {
     final int frameType;
     int offsetDelta;
 
@@ -40,11 +40,26 @@
         this.frameType = frameType;
     }
 
+    abstract int getStackItemsCount();
+
     static class SameFrame extends StackMapTableData {
         SameFrame(int frameType, int offsetDelta) {
             super(frameType);
             this.offsetDelta = offsetDelta;
         }
+
+        @Override
+        int getStackItemsCount() {
+            return 0;
+        }
+
+        @Override
+        public String toString() {
+            return "SAME"
+                       + ((frameType == SAME_FRAME_EXTENDED)
+                              ? "_FRAME_EXTENDED" : "")
+                       + "(" + offsetDelta + ")";
+        }
     }
 
     static class SameLocals1StackItem extends StackMapTableData {
@@ -54,6 +69,19 @@
             this.offsetDelta = offsetDelta;
             this.stack = stack;
         }
+
+        @Override
+        int getStackItemsCount() {
+            return 1;
+        }
+
+        @Override
+        public String toString() {
+            return "SAME_LOCALS_1_STACK_ITEM"
+                       + ((frameType == SAME_LOCALS_1_STACK_ITEM_EXTENDED)
+                              ? "_EXTENDED" : "")
+                       + "(" + offsetDelta + ")";
+        }
     }
 
     static class ChopFrame extends StackMapTableData {
@@ -61,6 +89,16 @@
             super(frameType);
             this.offsetDelta = offsetDelta;
         }
+
+        @Override
+        int getStackItemsCount() {
+            return 0;
+        }
+
+        @Override
+        public String toString() {
+            return "CHOP(" + offsetDelta + ")";
+        }
     }
 
     static class AppendFrame extends StackMapTableData {
@@ -70,6 +108,16 @@
             this.offsetDelta = offsetDelta;
             this.locals = locals;
         }
+
+        @Override
+        int getStackItemsCount() {
+            return 0;
+        }
+
+        @Override
+        public String toString() {
+            return "APPEND(" + offsetDelta + ")";
+        }
     }
 
     static class FullFrame extends StackMapTableData {
@@ -81,6 +129,16 @@
             this.locals = locals;
             this.stack = stack;
         }
+
+        @Override
+        int getStackItemsCount() {
+            return stack.length;
+        }
+
+        @Override
+        public String toString() {
+            return "FULL(" + offsetDelta + ")";
+        }
     }
 
     static StackMapTableData getInstance(DataInputStream in, MethodData method)