Win a copy of Programmer's Guide to Java SE 8 Oracle Certified Associate (OCA) this week in the OCAJP forum!
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic

Generic Confusion

 
Prashant Kataria
Greenhorn
Posts: 3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
public static <E extends Number> List<? super E> process(List<E> num)

this is the method's signature.
i want to use method like this
//Insert cod here
output=process(input);

which pair i should put at //Insert code here so that my code compile? at least is should accept input and output?

ArrayList<Integer> input=null;
ArrayList<Integer> output=null;

ArrayList<Integer> input=null;
List<Integer> output=null;

a. ArrayList<Integer> input=null;
List<Number> output=null;

b. List<Number> input=null;
ArrayList<Integer> output=null;

c. List<Number> input=null;
List<Number> output=null;

d. List<Integer> input=null;
List<Integer> output=null;

e. ArrayList<> input=null;
ArrayList<> output=null;

the answer in My book (SCJP 310-055 by Kathy Sierra and Bert Bates)
is b,e,f
but practically when i tested the code none of copiled.
please help to get answere
 
Barry Gaunt
Ranch Hand
Posts: 7729
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
That's correct - it does not compile for any of the choices. Please see the K & B errata for the correction to the question.

K & B errata
[ September 16, 2006: Message edited by: Barry Gaunt ]
 
Prashant Kataria
Greenhorn
Posts: 3
  • Mark post as helpful
  • send pies
  • Quote
  • Report post to moderator
Thnaks for help.
 
  • Post Reply
  • Bookmark Topic Watch Topic
  • New Topic