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Generic code help

 
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Is it because of '? extends ' instead of '? super' expression, the compiler wont let me add anything to the list. The code is from Khalid Mudgal book, a bit tweaked by me.
 
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Is it because of '? extends ' instead of '? super' expression, the compiler wont let me add anything to the list.



Yes.
But it's important to understand why. I suggest you go through the following post also

https://coderanch.com/t/627111/java-programmer-SCJP/certification/difference-List-super-Dog-animals#2869356

and try to understand the question and the responses. I think that might give you more clarity.

 
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Have a look at this post
 
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