Unchecked cast warning?

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Knute Johnson - 01 Nov 2006 20:12 GMT

I'm trying to read a Hashtable from an ObjectInputStream and getting an
Unchecked cast warning in the compiler.

Hashtable<Integer,String[]> table =
(Hashtable<Integer,String[]>)ois.readObject();

com\knutejohnson\redrock\scores\ScoresServer.java:209: warning:
[unchecked] unch
ecked cast
found : java.lang.Object
required: java.util.Hashtable<java.lang.Integer,java.lang.String[]>
(Hashtable<Integer,String[]>)ois.readObject();
^
1 warning

Where am I going wrong here?

Thanks,

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Knute Johnson
email s/nospam/knute/

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Thomas Hawtin - 01 Nov 2006 20:49 GMT

> I'm trying to read a Hashtable from an ObjectInputStream and getting an
> Unchecked cast warning in the compiler.
>
> Hashtable<Integer,String[]> table =
> (Hashtable<Integer,String[]>)ois.readObject();

This seems to be a common problem...

http://groups.google.com/group/comp.lang.java.programmer/tree/browse_frm/thread/
7b7457c1598473ba/5d022881ad375d93#doc_06f9e33d0ffd3e41

/**
* @throws ClassCastException
* @see ObjectInputStream#readObject
*/
@SuppressWarnings("unchecked")
static <T> readObject(
ObjectInputStream in
) throws IOException, ClassNotFoundException {
return (T)in.readObject();
}

Tom Hawtin

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su_dang@hotmail.com - 01 Nov 2006 21:01 GMT

> > I'm trying to read a Hashtable from an ObjectInputStream and getting an
> > Unchecked cast warning in the compiler.
[quoted text clipped - 18 lines]
>
> Tom Hawtin

There was no way for the compiler to make sure that the object type is
correct; hence, it issues the warning. As long as you know what you
are doing, it should be ok.

Reply to this Message

Knute Johnson - 01 Nov 2006 23:59 GMT

>>> I'm trying to read a Hashtable from an ObjectInputStream and getting an
>>> Unchecked cast warning in the compiler.
[quoted text clipped - 21 lines]
> correct; hence, it issues the warning. As long as you know what you
> are doing, it should be ok.

Thanks.

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Knute Johnson
email s/nospam/knute/

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Knute Johnson - 01 Nov 2006 23:59 GMT

>> I'm trying to read a Hashtable from an ObjectInputStream and getting
>> an Unchecked cast warning in the compiler.
[quoted text clipped - 18 lines]
>
> Tom Hawtin

Thanks Tom.

Signature

Knute Johnson
email s/nospam/knute/

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Unchecked cast warning?

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