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Java Tutorial about List Interface. Question

Nick Widelec
Ranch Hand

Joined: Feb 28, 2013
Posts: 226

Hi all,
Do you know what the "val == null" flow control line mean? It is not related to the iteration of the list, what kind of value is "E val" suppose to be?
Studying for the OCP that's why i need to know all these details.

Thanks in advance.
The following bit of code has been taken from http://docs.oracle.com/javase/tutorial/collections/interfaces/list.html
The line of code I do not get, is the one commented out just to highlight the line within the code.


OCAJP 7, OCPJP 7
Winston Gutkowski
Bartender

Joined: Mar 17, 2011
Posts: 7838
    
  21

Nick Widelec wrote:Do you know what the "val == null" flow control line mean? It is not related to the iteration of the list, what kind of value is "E val" suppose to be?

Well, in the particular case you show, it's trying to find the element to replace. There's nothing in the rules that says a List can't contain null elements, and using equals() to check whether an object equals null doesn't make sense, because, in order to call the method, the object can't be null (and besides, you'll get a NullPointerException).

HIH

Winston

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Mansukhdeep Thind
Ranch Hand

Joined: Jul 27, 2010
Posts: 1157

Welcome to the ranch.

Do you know what the "val == null" flow control line mean? It is not related to the iteration of the list, what kind of value is "E val" suppose to be?


I believe you are new to Java language? Is that correct?


~ Mansukh
Jeff Verdegan
Bartender

Joined: Jan 03, 2004
Posts: 6109
    
    6

Nick Widelec wrote:what kind of value is "E val" suppose to be?


http://docs.oracle.com/javase/tutorial/java/generics/
 
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