HashCode mock question

[Prasun Howlader]

This code is from <a href="http://www.skillfox.com" target="_blank" rel="nofollow">www.skillfox.com</a>
 
public class hashtest1 {
public static void main(String[] args) {
Foo f1= new Foo();
Foo f2=f1;
Foo f3= new Foo();
}
}
 
Assuming that Foo has correctly implemented hashCode and equals methods, which of the following will always print out "true" ?
 
a.if(f1.equals(f2)) System.out.println("true");
b.if(f1.hashCode() == f2.hashCode()) System.out.println("true");
c.if(f1.hashCode() != f3.hashCode()) System.out.println("true");
d.if(f1 == f2) System.out.println("true");

I choose a,b,d is it true.

[Nadeem Khan]

I think you are correct. "c" can also print true in some cases as unequal objects (f1 & f3) may have same hashcodes. So c is not "always" true but a,b & d will be.