IncompatibleClassChangeError

I am using BCEL since one week, and I have a problems
inserting a method in a method.
I want to insert in every method of every class, a method.
But my class doesn't work and I have a
IncompatibleClassChangeError error and I don't understand
from where, could be the error.
Sorry for my english.

this is my code:

try {
            JavaClass clazz =
Repository.lookupClass("front.persistance.action.BlobCl
obInitAction");
            ConstantPool constants  =
clazz.getConstantPool();
            cp = new ConstantPoolGen(constants);
            String nomStr = clazz.getClassName();
            nomClasseStr =
nomStr.substring(nomStr.lastIndexOf(".") + 1) +
".class";

            //si les variables de la classe ne contiennent
pas de logger
            //on insere partt
            Method[] methods = clazz.getMethods();
             //on parcours toutes les methodes pour les
rajouter
             for (int i = 0; i < methods.length; i++) {
                 String methodeStr = methods[i].toString();
                 String nomMethodeStr =
methodeStr.substring(0, methodeStr.indexOf("("));
                 nomMethodeStr =
nomMethodeStr.substring(nomMethodeStr.lastIndexOf("
") + 1);
                 if (!(nomMethodeStr.charAt(0) == '<'
                     &&
nomMethodeStr.charAt(nomMethodeStr.length() - 1) == '>'))
{
                    Method stripped = ajoutLogger(new
MethodGen(methods[i], clazz.getClassName(), cp));
                    if (stripped != null) {
                         methods[i] = stripped; // on écrase
la méthode par celle recrée
                     }
                 }
            }
           
clazz.setConstantPool(cp.getFinalConstantPool());
            clazz.dump(nomClasseStr);
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }

    private Method ajoutLogger(MethodGen methodGen) {
        try {
            InstructionFactory factory = new
InstructionFactory(cp);
            InstructionList instructionFinalList = new
InstructionList();
            InstructionList instructionList =
methodGen.getInstructionList();

            instructionFinalList.append(new PUSH(cp,
nomClasseStr));
           
instructionFinalList.append(factory.createInvoke("java.
io.PrintStream", "println",
                    Type.VOID, new Type[] { Type.STRING },
Constants.INVOKESTATIC));

            instructionFinalList.append(instructionList);
           
methodGen.setInstructionList(instructionFinalList);

            methodGen.setMaxStack();

            Method method = methodGen.getMethod();

            instructionFinalList.dispose();
           
System.out.println(methodGen.getMethod().toString());

            return method;
        } catch (Exception e) {
            System.err.println(e.getMessage());
            return null;
        }
    }

Matthew

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