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Posted to bcel-user@jakarta.apache.org by Andrew Cornwall <an...@gmail.com> on 2007/10/04 02:01:19 UTC

Having trouble with example in the manual

I'm trying to get the example in the manual running. The first thing I
noticed was:

      mg.addExceptionHandler(try_start, try_end, handler, "
java.io.IOException");

which under 5.2 doesn't seem to work. I replaced that with:

      mg.addExceptionHandler(try_start, try_end, handler, new ObjectType("
java.io.IOException"));


After doing this, I get a .class file - but when I try to run the class
under JDK 1.5, I see:

Exception in thread "main" java.lang.ClassFormatError: Illegal exception
table range in class file HelloWorld
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
        at java.security.SecureClassLoader.defineClass(
SecureClassLoader.java:124)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
        at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)

javap lists the exception table as being from 20 to 36 target 36 - which
looks valid to me:

   20:    getstatic    #27; //Field
java/lang/System.out:Ljava/io/PrintStream;
   23:    ldc    #29; //String Please enter your name>
   25:    invokevirtual    #35; //Method
java/io/PrintStream.print:(Ljava/lang/String;)V
   28:    aload_1
   29:    invokevirtual    #39; //Method
java/io/BufferedReader.readLine:()Ljava/lang/String;
   32:    astore_2
   33:    goto    37
   36:    return

Any idea why this might not be working?

Thanks!

    Andrew Jr.

Re: Having trouble with example in the manual

Posted by Andrew Cornwall <an...@gmail.com>.
Looks as if I found my answer. The manual reads:

il.append(new ASTORE(name));

 Upon normal execution we jump behind exception handler, the target address
is not known yet.

  GOTO g = new GOTO(null);
  InstructionHandle try_end = il.append(g);


but it should read:

      GOTO g = new GOTO(null);
      InstructionHandle try_end = il.append(g);

      il.append(new ASTORE(name));

in order to generate the same code that the JDK does.

     Andrew Jr.

On 10/3/07, Andrew Cornwall <an...@gmail.com> wrote:
>
> I'm trying to get the example in the manual running. The first thing I
> noticed was:
>
>       mg.addExceptionHandler(try_start, try_end, handler, "
> java.io.IOException");
>
> which under 5.2 doesn't seem to work. I replaced that with:
>
>       mg.addExceptionHandler(try_start, try_end, handler, new ObjectType("
> java.io.IOException"));
>
>
> After doing this, I get a .class file - but when I try to run the class
> under JDK 1.5, I see:
>
> Exception in thread "main" java.lang.ClassFormatError: Illegal exception
> table range in class file HelloWorld
>         at java.lang.ClassLoader.defineClass1(Native Method)
>         at java.lang.ClassLoader.defineClass (ClassLoader.java:620)
>         at java.security.SecureClassLoader.defineClass(
> SecureClassLoader.java:124)
>         at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
>         at java.net.URLClassLoader.access$100 (URLClassLoader.java:56)
>         at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
>         at java.security.AccessController.doPrivileged(Native Method)
>         at java.net.URLClassLoader.findClass(URLClassLoader.java :188)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
>         at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
>         at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:319)
>
> javap lists the exception table as being from 20 to 36 target 36 - which
> looks valid to me:
>
>    20:    getstatic    #27; //Field
> java/lang/System.out:Ljava/io/PrintStream;
>    23:    ldc    #29; //String Please enter your name>
>    25:    invokevirtual    #35; //Method
> java/io/PrintStream.print:(Ljava/lang/String;)V
>    28:    aload_1
>    29:    invokevirtual    #39; //Method
> java/io/BufferedReader.readLine:()Ljava/lang/String;
>    32:    astore_2
>    33:    goto    37
>    36:    return
>
> Any idea why this might not be working?
>
> Thanks!
>
>     Andrew Jr.
>