B class C "is-a", .
, B C, , Object, Object. , B is-a Object C is-a Object:
B b = new B();
Object ob = (Object)b;
C c = new C();
Object oc = (Object)c;
, , :
class B extends Object {
public void doSomething();
}
class C extends Object {
public void doAnotherThing();
}
, ?
C realC = new C();
realC.doSomething();
B c = (B)realC;
c.doSomething();
, C, doSomething, ?
, , B C , , .
, , , .