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instance of operator

cybel sheriden
Ranch Hand

Joined: Jan 18, 2005
Posts: 50
hi

instance of test can be don on obj ref variable ,to see if they are of a class or interface type.

i didn't understand the last three test(Foo[], Foo[1]) in table 3-2 (page 159 of K&B)
Mike Gershman
Ranch Hand

Joined: Mar 13, 2004
Posts: 1272
One key fact is that the element type, Foo, is different from the array type, Foo[].
If we say "Foo[] f;", then f is of type Foo[] but f is not of type Foo. f[1] is of type Foo.

The other key fact is that every array type is a subclass of Object[] and Object[] is a subclass of Object, so every array type is a subclass of Object.
[ February 22, 2005: Message edited by: Mike Gershman ]

Mike Gershman
SCJP 1.4, SCWCD in process
Animesh Shrivastava
Ranch Hand

Joined: Jul 19, 2004
Posts: 298
From Mike,
The other key fact is that every array type is a subclass of Object[] and Object[] is a subclass of Object, so every array type is a subclass of Object.


Mike, i guess this statement should be true only for array of reference types. I mean any integer array(int[]) is not a subclass of Object[].
Please let me know if i am wrong

Thanks
Mike Gershman
Ranch Hand

Joined: Mar 13, 2004
Posts: 1272
Mike, i guess this statement should be true only for array of reference types. I mean any integer array(int[]) is not a subclass of Object[].
Please let me know if i am wrong

You are correct. I forgot about arrays of primitives. They are subclasses of Object but not Object[].
 
It is sorta covered in the JavaRanch Style Guide.
 
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