Can I make class cast in Java using methods?

Question

So I do not like this for some reason:

((Foo) list.get(0)).getBar();

Is it possible to do something like this:

list.get(0).castTo(Foo.class).getBar();

Thanks.

Why do you not like the first (other than the problem that the precedence is always making you wonder about adding extra `()`)? — Hot Licks, Aug 04 '14 at 17:09
@HotLicks I think it breaks the view and slows down typing a lot. — Koray Tugay, Aug 04 '14 at 17:10
There is no dynamic cast mechanism, if that's what you're wondering. — Hot Licks, Aug 04 '14 at 17:10
Yeah, the cast syntax inherited from C sucks for several reasons. But it's far from the only wart on the language. — Hot Licks, Aug 04 '14 at 17:11
@HotLicks I am a beginner so this kind of caught my eye. The others I would not know really. — Koray Tugay, Aug 04 '14 at 17:11
May not be applicable for a broader context, but at least in this example you can avoid casting by generics — 6ton, Aug 04 '14 at 17:12
Just consider it a minor wart. It's that way for historical reasons, and it's not going to change, so we live with it. Just be thankful you're not dealing with C strings and arrays. — Hot Licks, Aug 04 '14 at 17:13
Do understand that if you use one of the suggested "alternatives" then others (including your instructor) will have trouble reading your code and will consider it to have non-standard "standards". — Hot Licks, Aug 04 '14 at 17:15

Kayaman · Answer 1 · 2014-08-04T17:22:28.860

3

You do have Class.cast(Object obj); method. But it would be stupid to use instead of the regular way just because you don't happen to like it.

It's also an extra method call instead of a compile-time construct, so they're not directly equivalent to each other.

Not to mention that 6ton already mentioned in the comments that the example is avoidable with generics...

edited Aug 04 '14 at 17:22

answered Aug 04 '14 at 17:09

Kayaman

What is the reasonable reason to use it? – Koray Tugay Aug 04 '14 at 17:10
1

When you're working with a lot of reflection and generics. So quite rarely. – Kayaman Aug 04 '14 at 17:12

score 2 · Accepted Answer · edited May 23 '17 at 12:05

2

You can use class.cast(Object). Read Java Class.cast() vs. cast operator.

Foo.class.cast(list.get(0)).getBar();

However, I suggest you to use a variable.

Foo foo = (Foo)list.get(0);
Bar bar = foo.getBar();

edited May 23 '17 at 12:05

Community

answered Aug 04 '14 at 17:12

spongebob

1

Just because you **can** use it doesn't mean you **should**. – Kayaman Aug 04 '14 at 17:14

2 Answers2