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I have a java class that consist of an inner interface, and plan to implement the implementation class during runtime with asm bytecode injection. 

package my.example;
public class X{
    public static interface XInt{
        public void getX();
    }
    //the following class that implement the interface will be defined during runtime.
    //I put it here just to show how the implementation will look like
    public static XImpl extend Y implements XInt{
        public void getX(){//implementation code}
    }
}

I am sure my asm code is correct, but the thing is after defining the class and call Class.forName("my.example.X$XImpl"), I get the following error:

> Bad <init> method call
Exception Details:
  Location:
    my/example/X$XImpl.<init>()V: invokespecial
  Reason:
    Type 'my/other/package/Y' is not assignable to 'my/example/X$XImpl'

My guess is that the class Y is not available during runtime yet? I have no idea.. Any help would be appreciated!

EDIT: The way I load XImpl is very simple: 

defineClass("my.example.X$XImpl", getXImplByte());
Class.forName("my.example.X$XImpl"); //fails here

The reason why im sure my byte code and class loading method is right because if i define the implementation class without extending any other class, it will work fine

Syenun
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1 Answers1

2

Seems that ASM classloader isn't a child of X classloader, so there is two different classes (even though they are identical), which can't be casted to each other.

Try to use:

Method m = ClassLoader.getDeclaredMethods("defineClass", String.class, byte[].class, int.class, int.class);
m.setAccessible(true);
m.invoke(X.class.getClassLoader(), ...);
qwwdfsad
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  • thanks ! apparently i have some internal problem, your answer gave me a very good direction – Syenun May 11 '15 at 20:44
  • Could you tell about problem? I'm interesting, what else can cause this error – qwwdfsad May 11 '15 at 20:55
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    I have my own implementation of classLoader that overwrites/extend some of the functionality. Things start getting very interesting when you are messing with Java class path and doing dynamic binding.. – Syenun May 12 '15 at 16:45