Generic method in generic class

[Richard Hayward]

Is it possible for a generic class to have a generic method, where the generic type parameter of the method is required to extend that of it's enclosing class?

For example:

class GenericTest{

  static class Animal{}
  static class Dog extends Animal{}
  static class Cat extends Animal{}

  static class MyClass<T>{
    <U extends T> void myMethod(U x){}
  }

  public static void main(String[] args){
    MyClass myClass = new MyClass<Animal>();
    myClass.myMethod(new Dog());       //ok
    myClass.myMethod(new Cat());       //ok
    myClass.myMethod(new Object());    //should give compile error? 
                                       //Object does not extend Animal
  }

}

This code does compile & run without error, although it seems to me that there should be a compile failure at line 15 because myClass was created with an <Animal> generic type and myClass.myMethod() should therefore only take an argument whose type extends Animal.

[Sergej Smoljanov]

note you use raw type:

MyClass myClass =...

try to pass myMethod others object you know.
if you change

MyClass<Animal> myClass = new MyClass<>();

you have different behavior.

[Richard Hayward]

Thank you Sergej.

I'd overlooked that. Now I get the compile error I was expecting.

Richard