Problem with Generics?

[Deepak Chopra]

Hi All,
I was testing the K&B question about generics and found the following problem..which book says is right but it giving me an error..?

  public static void main(String... args){
           ArrayList<Integer> list = new ArrayList<Integer>();
           list.add(5);
           list.add(8);
           List<Integer> output;
           output = process(list);
        
    }
     public static<E extends Number> List<? super E> process(List<E> list){
      return list;
    }   

according to book it should compile..but it is giving me the following error?

 //Error(16,16): incompatible types; found: interface java.util.List<? super java.lang.Integer>, required: interface java.util.List<java.lang.Integer>   

I am finding it really difficult to understand..how to established relationship between..
type of output and List< ? super E>

can any one help me to understand..?

[Nadeem Khan]

Dude this question is wrong! refer the 2 prev topics which discussed this!

[Deepak Chopra]

you mean to say...question given in the book is wrong or something else.?
please clarify...!!

[ahmed yehia]

This is an Errata question, the correct method signature is:

public static <E extends Number> List<E> process(List<E> nums)

[Deepak Chopra]

Hi,
Is there any form which contain all the Errata questions?

[ahmed yehia]

Check SCJP forum main page for: K&B Errata

[Deepak Chopra]

Well I found one "Mock Exam Errata"..and it has only one post..!!
Is there any post or link where i can find all the mistakes in K&B..!!

Thanks in advance..!!

[Abhijit Das]

Go to the link

https://coderanch.com/t/257589/java-programmer-SCJP/certification/SCJP-Errata-Updated


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