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regarding instanceof operator

Vasudhaiv Naresh
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Joined: May 13, 2005
Posts: 57
Hi all,
I had just seen somewhere that using the instanceof operator is not advised. I'd like to know the reason why it shouldn't be used.
Jeff Albertson
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Joined: Sep 16, 2005
Posts: 1780
Here's a typical use of instanceof that's problematic.If this is an open-ended hierarchy, then as more classes extend A, you'll have to find the code like method f throughout your program and add more cases. A better solution in this case would be if there were a polymorphic method doF() that you could invoke:This doesn't mean that you should never use instanceof. There are places where it's unavoidable.

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Henrique Sousa
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Joined: Apr 29, 2004
Posts: 92
There are times when you just cannot avoid using instanceof, like when you override Object.equals or Comparable.compareTo. Sometimes the abstraction and contract just won't let you be specific when taking a parameter.

Henrique Sousa<br />SCJP 1.4<br /> <br />All men die, not all men really live - Braveheart, 1995
I agree. Here's the link:
subject: regarding instanceof operator
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