基于编译器解析的Java重载

Question

class Animal {}

class Bull extends Animal {}

class Test {

  void m1(Animal a) {
    System.out.println("Calls Animal class");
  }

  void m1(Bull b) {
    System.out.println("Calls Bull class");
  }

  public static void main(String...args)

  {

    Test t = new Test();

    Animal a = new Bull();

    t.m1(a);
  }
}

RESULT: Calls Animal Class

In the above code, both methods having arguments types of parent and child reference can accept the argument of the Bull object. However, only the method containing the parent reference gets executed. Why does this happen?

Answer 1

This happens because you have two different methods with different reference types one Animal and another Bull . So when you can a method and pass the parameter type of Animal , this method has been called

void m1(Animal a) {
   System.out.println("Calls Animal class");
}

Your assumption is true about Java polymorphism when you have a reference of Animal points to object of Bull so whatever you use inside in the two objects will use the child in case of overload otherwise will use Parent if the child doesn't contain override methods. The opposite in C# language depends on the reference to execute not the object.

But in your case you have a different case, you have two different methods and different parameters, so the compiler finds the method that matches the parameter type and calls it.