Wild card generic type

[nitin pokhriyal]

I was going through the tutorials i saw

ArrayList<?> coll1 = new ArrayList <?> (); // error

will not compile but i am able to compile it. Please advice where i am wrong?

[Manfred Klug]

Originally posted by nitin pokhriyal:
but i am able to compile it.

Interesting. For me, compilation fails.

[Christophe Verré]

Please advice where i am wrong?

You're compiling the wrong class ?

[nitin pokhriyal]

Strange thing if i am trying to compile it wil Jdeveloper it will compile fine for me but if i try to use jdevelopers jdk in comand prompt i got

1. B.java:8: unexpected type
2. found : ?
3. required: class or interface without bounds
4. ArrayList<?> arr=new ArrayList<?>();


^

[Chandra Bhatt]

ArrayList<?> coll1 = new ArrayList <?> (); // error 

I don't see anything wrong here!


Thanks,

[nitin pokhriyal]

Chandra bhatt,

That is what i am not getting from jdeveloper but when i try to compile from command prompt i got error.

[Barry Gaunt]

Originally posted by Chandra Bhatt:

ArrayList<?> coll1 = new ArrayList <?> (); // error 

I don't see anything wrong here!


Thanks,

Read this FAQ entry.

[nitin pokhriyal]

that is the reference material i refered but y chandra is not getting error even if i use jdeveloper i am also not getting that error as i explained in my previous post.

[Chandra Bhatt]

Ooops!
I missed that.

Thanks Barry

ArrayList<?> coll1 = new ArrayList <?> (); // error 

It wont compile. While constructing an parameterized object, you must give
it a type that is actual object and not wildcard. You can use wildcard
parameterized type with ref variable not object type.