Question

I can not understand the following code:

Constructor<T>[] constructors = (Constructor<T>[]) clazz.getConstructors();  
for(int i = 0; i < constructors.length; i++){  
  Constructor<T> constructor = constructors[i];    
  if (constructor.getParameterTypes().length>0){    
    T instanceObject = constructor.newInstance(new Object[constructor.getParameterTypes().length]);  
        break;  
  }  

}    

Have omitted try/catch and other stuff for clarity.
I can not understand how this works: T instanceObject = constructor.newInstance(new Object[constructor.getParameterTypes().length]);
It calls a constructor that has parameters, but passes as arguments Object?
How does this work? Passing Object independent of the actual formal parameters?

Answer 1

It attempts to pass dummy parameters which are all null. This can give you an Object but it doesn’t mean it will be a useful one. 😉

I am not sure why it skips zero length constructors as this is the one constructor you are likely to be able to pass no arguments successfully.