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Generics Question

Chandana Garlapati
Ranch Hand

Joined: Jul 06, 2009
Posts: 97


This question is from javabeat
could anyone explain??
Andriy Pererva
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Joined: Jul 19, 2009
Posts: 73
The warning is because raw List reference is referenced to parametrized LinkedList.
LinkedList parametrization means that you have an intent to explcitly restrict collection items to String type, but the raw reference spoils all the generic effort and allows to add any object (like Integer on line 7), despite of LinkedList parametrization


SCJP 6.0(95%), SCWCD 5(94%), SCJD (working on B&S v.2.3.1)
Chandana Garlapati
Ranch Hand

Joined: Jul 06, 2009
Posts: 97
But the rule is:

Non Generic ref. type + Generic instant --> compiles w/o warning
Generic ref.type + Non Generic instant --> compiles with warning
Ankit Garg
Sheriff

Joined: Aug 03, 2008
Posts: 9307
    
  17


This line of code does not generate any compiler warning. How did you compile your code?? Did you use any IDE??


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Chandana Garlapati
Ranch Hand

Joined: Jul 06, 2009
Posts: 97
Ankit Garg wrote:
This line of code does not generate any compiler warning. How did you compile your code?? Did you use any IDE??


No i am trying in notepad and command prompt.
Leonardo Carreira
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Joined: Apr 07, 2009
Posts: 489

Hi Chandana..

i think you need to use Netbeans or other Java IDE..
it could help us to know the warning..


Sorry, perhaps my english language isn't too good.. Prepare for SCJP 6, Please God help me.. ☼
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Dragos Nica
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Joined: Oct 25, 2009
Posts: 39
Chandana Garlapati wrote:
Ankit Garg wrote:
This line of code does not generate any compiler warning. How did you compile your code?? Did you use any IDE??


No i am trying in notepad and command prompt.


The warning will occur only if you are trying to add something.
Every time when you try to add something to a non parameterized collection , the warning will occur. As such a list can accept any type of object, this is the compiler's way to tell you that you must pay attention to what you are adding to the list.


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subject: Generics Question