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  ArrayList and elements  (Read 747 times)
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Offline chaosblasian

Innocent Bystander




Java games rock!


« Posted 2005-04-05 11:09:23 »

first off...Hi! first time posting.

ok, ive been using java for a little over half a year now and the APIs, google, and trial and error have solved all my problems up until now.
ive learned that u can set an ArrayList's type by using the <symbols> and the object name. my question is two part.

ive got a parameter that can take a superclass(or basically a designed class to help with interfacing) and i want the method to get the actual sub class.

secondly i want to to create an arraylist fixed with the obtained subclass if possible.

iv tried googling it and no real help there. and the api refers u back to arraylist when u click on element. ive tried using the object method getClass(), but that wont go into the <object> area and work with the compiler. Anyone able to help me with any of those things? it would be much appreciated.
Offline princec

« JGO Spiffy Duke »


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« Reply #1 - Posted 2005-04-05 11:45:45 »

I suspect that you are falling foul of a design feature in the JVM which is 'type erasure'. The JVM does not understand generic types; an ArrayList<Mystuff> is just an ArrayList to the JVM. getClass() therefore just returns ArrayList. Generics are only used for compile-time checking, not runtime type safety.

Cas Smiley

Offline Orangy Tang

JGO Kernel


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Monkey for a head


« Reply #2 - Posted 2005-04-05 11:55:51 »

Quote

ive got a parameter that can take a superclass(or basically a designed class to help with interfacing) and i want the method to get the actual sub class.

IMHO, that sounds like you've got a problem in your design somewhere...

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