Re: ClassReader exception due to bad bytecode

Thanks for the suggestion. The result of javap - v -p as following:

Exception in thread "main" java.lang.NullPointerException
        at sun.tools.javap.JavapPrinter.javaclassname(JavapPrinter.java:856)
        at sun.tools.javap.JavapPrinter.printclassHeader(JavapPrinter.java:62)
        at sun.tools.javap.JavapPrinter.print(JavapPrinter.java:38)
        at sun.tools.javap.Main.displayResults(Main.java:202)
        at sun.tools.javap.Main.perform(Main.java:61)
        at sun.tools.javap.Main.entry(Main.java:49)
        at sun.tools.javap.Main.main(Main.java:34)

I can't tell what is wrong with my bytecode based on the above messages. I would guess the problem is in the header, is it a wild guess? Are there tools that help to identify problems in the bytecode? Please advice.

--- On Tue, 1/25/11, Dave Brosius <[email protected]> wrote:

From: Dave Brosius <[email protected]>
Subject: Re: [asm] ClassReader exception due to bad bytecode
To: [email protected], [email protected]
Date: Tuesday, January 25, 2011, 7:20 PM



  

    
    
  Does javap -v -private YourClass

    

    produce anything different?

    

    On 01/25/2011 04:54 PM, Buu Vinh wrote:
    
      
        
          
            After using ASM 3.2
              for the bytecode instrumentation, I tried to verify the
              result by feeding the transformed bytecode to ClassReader
              and invoking ASMifierClassVisitor:

              .........

              cr = new ClassReader(originalBytes);

              cw = new ClassWriter(cr,ClassWriter.COMPUTE_MAXS);

              BciClassAdapter bca = new BciClassAdapter(cw, iClass);

              cr.accept(bca, 0);

              byte[] newBytes = cw.toByteArray();

              

              ClassReader
                cr = new ClassReader(newBytes);  

              File tmpFile = new File(fileName);

              File tmpDir = tmpFile.getParentFile();

              tmpDir.mkdirs();

              ClassVisitor cv = new ASMifierClassVisitor(new
              PrintWriter(tmpFile));

              cr.accept(cv, 0);

              ........

              

              I got ClassReader Exception when processing "newBytes":

              

              java.lang.ArrayIndexOutOfBoundsException: Array
                  index out of range: 51966   

               at
              com.bv.asm.ClassReader.readUTF8(ClassReader.java:1946)                
              

               at
              com.bv.asm.ClassReader.readClass(ClassReader.java:2015)               
              

               at
              com.bv.asm.ClassReader.getClassName(ClassReader.java:229)             
              

               at
              com.bv.bci.instrument.InstrumentClass.verify(InstrumentClass.java:287)
              

              

              Apparently ClassReader was not able to parse "newBytes", I
              assumed that "newBytes" was ill-formated due to some kind
              of problem in my bytecode instrumenation, but I could not
              locate the error. I used ClassWriter.COMPUTE_MAXS, but it
              did not help. Please advice. Thanks

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