About Question enthuware.ocajp.i.v7.-2-.1291 : about implict and explicit cast

[flex567]

System.out.println( ( (A) b ).fi ); What is this, upcasting?

[admin]

System.out.println( ( (A) b ).fi ); What is this, upcasting?

Yes, because you are casting a reference of a subtype to a supertype.
Try this if you are not clear - https://stackoverflow.com/questions/234 ... t-to-class

[flex567]

I think I understand:

A a = new B(); //upcasting

B b = new B();
a = (A) b;//also upcasting
(A) b;//also upcasting

[admin]

There is no cast in A a = new b(); ! Also it should new B() not new b.

[flex567]

It is implicit upcast.

[admin]

This is implicit "widening" not implicit upcast. There is nothing like implicit or explicit cast. Only cast. Cast is done using the cast operator i.e. ( ). If there is no cast operator, there is no cast.

[flex567]

http://www.baeldung.com/java-type-casting

[admin]

This is that particular author's view. You can take it up with him/her. There is no such term as implicit or explicit cast in the Java language specification. The term implicit cast or explicit cast is nonsensical. Either there is a cast or there is not. There is widening and widening can be explicit (i.e. using a cast) or implicit (i.e. without use a cast).

By the way, the book you quoted seems to be about Spring so I don't think the author is paying too much attention about such small technicality that has nothing to do with spring.

-Paul.

[flex567]

I noticed it on other pages as well.

[admin]

You can talk to the author or ask someone else if you are not satisfied. Our view on this is quite clear.

HTH,
Paul.

[admin]

This discussion has nothing to do with the exam so I am splitting it into a separate topic.