diff -r b06660b614db -r 32653a09f0db javap/src/main/java/sun/tools/javap/ClassData.java
--- a/javap/src/main/java/sun/tools/javap/ClassData.java	Fri Nov 09 21:33:22 2012 +0100
+++ b/javap/src/main/java/sun/tools/javap/ClassData.java	Sat Nov 10 19:01:28 2012 +0100
@@ -65,18 +65,8 @@
     /**
      * Read classfile to disassemble.
      */
-    public ClassData(InputStream infile){
-        try{
-            this.read(new DataInputStream(infile));
-        }catch (FileNotFoundException ee) {
-            error("cant read file");
-        }catch (Error ee) {
-            ee.printStackTrace();
-            error("fatal error");
-        } catch (Exception ee) {
-            ee.printStackTrace();
-            error("fatal exception");
-        }
+    public ClassData(InputStream infile) throws IOException {
+        this.read(new DataInputStream(infile));
     }
 
     /**
@@ -271,10 +261,6 @@
         return toHex(val, width);
     }
 
-    public void error(String msg) {
-        System.err.println("ERROR:" +msg);
-    }
-
     /**
      * Returns the name of this class.
      */
@@ -571,9 +557,9 @@
             for (int k=0; k<len; k += Character.charCount(cp)) {
                 cp=name.codePointAt(k);
                 if (cc=='/') {
-                    if (!Character.isJavaIdentifierStart(cp)) break fullname;
+                    if (!isJavaIdentifierStart(cp)) break fullname;
                 } else if (cp!='/') {
-                    if (!Character.isJavaIdentifierPart(cp)) break fullname;
+                    if (!isJavaIdentifierPart(cp)) break fullname;
                 }
                 cc=cp;
             }
@@ -660,4 +646,12 @@
     public int getMajor_version(){
         return major_version;
     }
+
+    private boolean isJavaIdentifierStart(int cp) {
+        return ('a' <= cp && cp <= 'z') || ('A' <= cp && cp <= 'Z');
+    }
+
+    private boolean isJavaIdentifierPart(int cp) {
+        return isJavaIdentifierStart(cp) || ('0' <= cp && cp <= '9');
+    }
 }