Injecting Instrumented classes to classpath at runtime with javaassist

InstrClass.java

package de.mzte.test;

public class InstrClass {
    public static void sayHello() {
        System.out.println("Hello!");
    }
}

Main.java

package de.mzte.test;

import javassist.*;

import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

public class Main {

    public static void main(String[] args) throws NotFoundException, CannotCompileException, IOException, IllegalAccessException, NoSuchMethodException, InvocationTargetException {
        //Instrument class
        ClassPool pool = ClassPool.getDefault();
        CtClass cc = pool.get("de.mzte.test.InstrClass");
        CtMethod m = cc.getDeclaredMethod("sayHello");
        m.insertBefore("System.out.println(\"Someone Said Hello!\");");
        cc.defrost();
        cc.writeFile();
        //Inject class into classpath
        ClassLoader classLoader = ClassLoader.getSystemClassLoader();
        Method method = ClassLoader.class.getDeclaredMethod("addClass", Class.class);
        method.setAccessible(true);
        method.invoke(classLoader, cc.toClass());

        //Call Like normal
        InstrClass.sayHello();
        InstrClass.sayHello();
        InstrClass.sayHello();
        InstrClass.sayHello();
    }

}