Doubt in K&B - Generics & Collections - Question 8

[Jeff Schuler]

In the K&B book for chapter 7, question 8, it says that 'E' is one of the correct responses. When I keyed it in (and added a main method), it gave a compiler error due to incompatible types. I put asterisks around the lines in question. Can someone explain to me why it is considered a valid option?

   
import java.util.*;
 
public class AccountManager
{
    private Map accountTotals = new HashMap();
    private int retirementFund;
    
    public int getBalance(String accountName) 
    {
[B]// ***********
Integer total = accountTotals.get(accountName);
if (total == null)  total = 0;
return total;
[/B]// ***********
    }
    
    public void setBalance(String accountName, int amount)
    {
accountTotals.put(accountName, Integer.valueOf(amount));
    }
    
    public static void main(String[] args)
    {
AccountManager am = new AccountManager();
am.setBalance("Jeff", 10000);
am.retirementFund = am.getBalance("Jeff");
System.out.printf("%d", am.retirementFund);
    }
    
} 
 

[ July 02, 2007: Message edited by: Jeff Schuler ]

[Remko Strating]

Option E is valid. You have forgotten something in your code

Your line 17 should be

  
Integer total = (Integer)accountTotals.get(accountName);

If not you have a compiler error incompatible types, because the HashMap is returning an object and not an Integer.

[Manfred Klug]

Originally posted by Jeff Schuler:
In the K&B book for chapter 7, question 8, it says that 'E' is one of the correct responses.

You must apply all of the changes.

[Jeff Schuler]

Originally posted by Manfred Klug:
You must apply all of the changes.

Ok. I was treating each change independently. So the question is asking if all generic changes were made, which ones would be valid.

Thanks.

[Jeff Schuler]

Originally posted by Remko Strating:
Option E is valid. You have forgotten something in your code

Your line 17 should be

  
Integer total = (Integer)accountTotals.get(accountName);

If not you have a compiler error incompatible types, because the HashMap is returning an object and not an Integer.

Option E doesn't have the Integer casted. It turns out I misunderstood the question though.