public class TargetClass { public void doSomething() { } } ClassPool pool = ClassPool.getDefault(); CtClass targetClass = pool.get("TargetClass"); CtMethod doSomethingMethod = targetClass.getDeclaredMethod("doSomething"); Class modifiedClass = targetClass.toClass(); Object modifiedObject = modifiedClass.newInstance(); Method modifiedMethod = modifiedObject.getClass().getMethod("doSomething"); modifiedMethod.invoke(modifiedObject);