How to create a default constructor with Byte Buddy

Question

I want to intercept some method calls on one of my classes but those classes dont have a default constructor.

Given the following class, how would I setup Byte Buddy

Answer 1

You cannot define a constructor without any byte code. This would be an abstract constructor what is illegal in Java. I am going to add a more precise description to the javadoc for a future version. Thanks for bringing this to my attention.

You need to define a super method call which is required for any constructor:

DynamicType.Builder builder = ...
builder = builder
  .defineConstructor(Collections.<Class<?>>emptyList(), Visibility.PUBLIC)
  .intercept(MethodCall
               .invoke(superClass.getDeclaredConstructor())
               .onSuper())

As for wheather you should use Byte Buddy here: I cannot tell you from the little code I saw. The question you should ask: Does it make my code easier, both considering the amount of code and the complexity of following it? If Byte Buddy makes your code easier to use (and to run), use it. If not, don't use it.