How can I get declared classes in method?

Question

This is Test class.

package com.reflection;

import com.reflection.test.A

public class Main {
  public void setA() {
    A a = new A();
  }
}

Then, I used ClassLoader for accessing and manipulating classes, fields, methods, and constructors as the code below

Class cls = cl.loadClass("com.reflection.Main");

Actually I really want to get A class by using cls and already tried to use getDeclaredClasses and getClasses but the result was nothing.

Answer 1

You can't do that with pure Java reflection. Reflection will let you look at classes and their members, but not at the code inside a method.

The easiest thing to do is probably to do javap -v somewhere in the build process, parse the output for qualified class names and store them in a property file somewhere.

The harder version is to use a byte code tool like asm or ByteBuddy, write a visitor over all instructions in your class and store all classes from all instructions in a Map. While this is theoretically the elegant approach, it will probably be a nightmare.