静态方法的继承和多态

Question

How does inheritance and polymorphism work with static methods? Could someone explain what the proper output is supposed to be here and how it was derived?

class A { public static int get() { return 17; } }
class B extends A { public static int get() { return 42; } }


 Main
 A x = new B();
 x.get();

The error message,

The static method get() from the type A should be accessed in a static way

I think I know how to access to it in a static way but this is a question from class and its sort of implied that one or the other values would be returned

In our program, we have the class definitions:

class A { public static int get() { return 17; } }
class B extends A { public static int get() { return 42; } }

and somewhere else we declare A x = new B();

What number will the call x.get() return?

Answer 1

The invocation will return the int value 17 .

static methods are not inherited.

static methods are bound and invoked based on the type of the expression they are invoked on.

So

x.get();

where x is of type A invokes A 's implementation. Note also that static methods don't need an instance to be invoked.

These would work as well.

((A) null).get();
A.get();
...
public static A someMethod() {}
...
someMethod().get();

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The message you got is a warning, not an error.