doubt about MasterExam question

[Niala Nirell]

Here there is the question in the MasterExam:

public class SortOf {
   String name;
   int bal;
   String code;
   short rate;
 
   public int hashCode() {
return (code.length()*bal);
   }
 
   public boolean equals(Object o) {
//insert code here
   }
 
 
}

Which of the following will fulfill the equals() and hashCode() contracts for this class?
(Choose all that apply)

A: return ((SortOf)o).bal == this.bal;

B: return ((SortOf)o).code.length() == this.code.length();

C: return ((SortOf)o).code.length()*((SortOf)o).bal == this.code.length();

D: return ((SortOf)o).code.length()*((SortOf)o).bal*((SortOf)o).rate == this.code.length()*this.bal*this.rate;

ANSWER : C and D

I'm not agree with D because i made an example where
SortOfObject1.equals(SortOfObject2) and SortOfObject1.hashCode()!=SortOfObject2.hashCode()

My example:

public class SortOf {
String name;
int bal;
String code;
short rate;
@Override
public int hashCode() {
return (code.length()*bal);
}
@Override
public boolean equals(Object o) {
return ((SortOf)o).code.length()*((SortOf)o).bal*((SortOf)o).rate == this.code.length()*this.bal*this.rate;
}
 
public static void main(String args[]){

SortOf so1 = new SortOf();
so1.code = "aaaaa";
so1.bal = 3;
so1.rate = 2;
 
SortOf so2 = new SortOf();
so2.code = "aaaaa";
so2.bal = 6;
so2.rate = 1;

System.out.println(so1.equals(so2));
System.out.println(so1.hashCode());
System.out.println(so2.hashCode());

}
 
}

the output is :
true
15
30


Maybe I'm wrong with something, please tell me.

Thank you
[ March 12, 2008: Message edited by: Alain Sellerin ]

[Jelle Klap]

Technically none of them do, as for any null reference that is passed as an argument to equals(), instead of returning false as the contract for equals specifies, these implementations all throw a NullPointerException. As the contract for equals() is never completely satisfied for any implementation, I'd say the question is flawed.
[ March 12, 2008: Message edited by: Jelle Klap ]

[Niala Nirell]

thank you for your comment