For Generics Extra Reading Suggestion Required

[Prithvi Sehgal]

Dear All,

I was reading K&B generics chapter 7. I finished with it and tried solving the exercise. I feel i am lacking in a lot of
concepts i suppose.

For example syntax like this

    
List<List<Integer>> table = new ArrayList<List<Integer>>();

Tricky syntax. I am making a lot of mistakes when i am encountering questions like Generic typing. Can someone give me
some pointers towards good reference for further reading.

If not generics suggestion, then any guidance, because i am really performing bad in Generics. Advice needed.

Thanks,

[Rajeev Rnair]

Prithvi Sehgal wrote:Dear All,

I was reading K&B generics chapter 7. I finished with it and tried solving the exercise. I feel i am lacking in a lot of
concepts i suppose.

For example syntax like this

    
List<List<Integer>> table = new ArrayList<List<Integer>>();

Tricky syntax. I am making a lot of mistakes when i am encountering questions like Generic typing. Can someone give me
some pointers towards good reference for further reading.

If not generics suggestion, then any guidance, because i am really performing bad in Generics. Advice needed.

Thanks,

Hi Prithvi, have you tried Examlab questions? It do have a lot of good generics questions. Please go through the explanations and do lot of small code where concepts are not clear.
I answered wrong the above question first time!

[Prithvi Sehgal]

So i am not the only one in this league. Glad you joined me as a first timer also Rajeev.

Rajeev, can you explain me what the above statement really means? It's such a weird syntax.

Best Regards

[Rajeev Rnair]

Prithvi Sehgal wrote:

So i am not the only one in this league. Glad you joined me as a first timer also Rajeev.

Rajeev, can you explain me what the above statement really means? It's such a weird syntax.

Best Regards

Hi Prithvi,

It is same like

List<String> list = new ArrayList<String>();

Think about List<E> list = new ArrayList<E>();
Here "E" can be anything, String, or Integer or even List<Integer>
The tricky part is what ever E is, the right hand side has to be ArrayList<E>(), not ArrayList<subtype of E>(), not ArrayList<supertype of E>

If we define E as Integer

List<Integer> list = new ArrayList<Integer>();

Now let us change "E" to "List<Integer>"
Here you go!

List <   List<Integer>    > list = new AraryList<   List<Integer>   > (); //ok

Since "E" is "List<Integer>" here, you cannot replace right hand side with anything other than "E" which is "List<Integer>"

Hense the following are invalid:

List <   List<Integer>    > list = new AraryList<   List<Number>   > (); //wrong!

[Rahul Manikuntla]

Your explanation is very good to clear a lot of doubt.

[Maya Dolas]

Hi,

When I appeared for SCJP5, I was weary about the generics. After passing the exam I tried digging into it more and found a very good link and FAQ article specifically for Generics. Just google
Angelika Langer generics FAQ and you should find it. I definitely recommend it not just from exam perspective but also to gain important perspectives on Generics.

[Prithvi Sehgal]

Maya Dolas wrote:Hi,
I definitely recommend it not just from exam perspective but also to gain important perspectives on Generics.

Maya thank you very much. That seems a pretty valuable insight. I have noted it down. I am definitely going to check
it. Thanks again.

Best Regards,

[Ankit Garg]

I was also very bad at generics in the beginning, the resources I used (in addition to K&B) were Sun's Tutorial and Generics FAQ...

[Prithvi Sehgal]

Dear Ankit,

Thank you very much. I really appreciate that you shared your experience with me. Now i am at peace, i will concentrate more harder.

Best Regards,