1 Reply Latest reply on Feb 9, 2011 1:33 PM by cbruguera

ClassFile write(java.io.DataOutputStream out) generates empty file!!

cbruguera Feb 6, 2011 4:12 PM

Hello all, I'm working in a compiler that is generating bytecode, and I wish to only use those javassist classes that work with low-level bytecode (Bytecode, ClassFile, MethodInfo, FieldInfo, etc.). I'm not interested in high level runtime translation of any java code (so I barely need to use CtClass and similar).

The thing is I'm creating a ClassFile object, adding a MethodInfo structure, based on an existent bytecode object (mainCode) which I know is well built. But at the end I'm trying to write the file, and it creates it, but as a 0 byte .class file.

Is there anything that I might be missing?.. Here's my piece of code:

ClassFile initClass = getOrCreateClass("InitClass");
declaring = initClass;

MethodInfo mainMethod = new MethodInfo(initClass.getConstPool(), "main", Descriptor.ofMethod(CtClass.voidType, new CtClass[0]));
mainMethod.setCodeAttribute(mainCode.toCodeAttribute());
mainMethod.setAccessFlags(AccessFlag.PUBLIC);

try{
    initClass.addMethod(mainMethod);
}catch(DuplicateMemberException e){
    Errors.add("Definicion duplicada para \"Accion Principal\"");
}

writeFile(initClass);

The method getOrCreateClass is successfully instantiating a new ClassFile object and returning it.

...Any ideas?

1. Re: ClassFile write(java.io.DataOutputStream out) generates empty file!!

cbruguera Feb 9, 2011 1:33 PM (in response to cbruguera)

Oh, I forgot..

writeFile(initClass) will just do this:

public static void writeFile(ClassFile cf){
     try{
          cf.setVersionToJava5();
          cf.write(new DataOutputStream(new BufferedOutputStream(new FileOutputStream(cf.getName() + ".class"))));
     }catch(IOException e){
          Errors.add("Error al escribir el archivo " + name);
     }
}

I really need help