I'm reading through the Oracle doc, but I don't get something.
Suppose I have
public interface a {
//some methods
}
public class b implements a {
//some methods
}
What would be the difference between this:
a asd=new b();
and this:
b asf=new b();
There is no such thing. At least not compile.
a asd=new a(); // you can't instantiate an interface
and
b asf=new a(); // you can't instantiate an interface
You can do followings.
b asd=new b();
and
a asd=new b();
let say we have class b and interface a:
public interface a{
void foo();
}
public class b implements a{
@Override
void foo(){}
void bar(){}
}
then we create two instances:
a asd=new b();
b asf=new b();
now asdis instance of 'a' so it can access only methods declared in interface a (in this case method foo)
asf from other hand is instance of b so it can access both method defined in class b
a asd = new b() -- can be resolved at runtime
b bsd = new b() -- can be resolved at compile time.
you cannot instantiate an interface
if we suppose you mean a parent class, in the first case you cannot the access method(s) of class b
Suppose you have these classes:
public class a {
//some methods
}
public class b extends a {
//some methods
type method1(args) {...}
}
What would be the difference between?
a asd=new b(); // you cannot call method1 using asd
and
b asf=new b();
interface