Date and override equals()

Hi,
I have a class like the following:
import java.util.Date;
Class A {
Date date1;
String st;
public A (...){
...}
public boolean equals(Object o){
A other = (A)o;
boolean retval = false;
if(this == other) return true;
if(other instanceof A){
retval = retval && other.date1.equals(this.date1);
retval = retval && other.st.equals(this.st);
}
return retval;
}
public int hashCode(){
int result = 17;
result = 37*result + (int)(date1.getTime());
resulr = st == null ? result : 37 * result + st.hasCode();
}
}

When I try to compare two objects which are the same, it always tells me
they have different hashCode. I think something is wrong with equals()
method, just do not why it is not working.
Could anyone point out my mistakes?
regards,
[ August 28, 2003: Message edited by: rick collette ]

Well, looking at this method:

Note #1: This cast will fail if o isn't an instance of A.

Note #2: Since other is an A, this test is redundant.

Note #3, retval will always be false on entering this statement,

so it will always be false after evaluating it

Note #4: Same as #3.

So this method always returns false. I think you might be looking for something like

[ August 28, 2003: Message edited by: Ernest Friedman-Hill ]

Thanks. Sorry for having many senseless mistakes.
I used your code, but I still got the same error. I wonder if the way
I handle Date objects is wrong. Any inputs?
regards

Originally posted by Ernest Friedman-Hill:
Well, looking at this method:
public boolean equals(Object o){ A other = (A)o; // Note #1 boolean retval = false; if(this == other) return true; if(other instanceof A){ // Note #2 retval = retval && other.date1.equals(this.date1); // Note #3 retval = retval && other.st.equals(this.st); // Note #4 } return retval; }

Note #1: This cast will fail if o isn't an instance of A.
Note #2: Since other is an A, this test is redundant.
Note #3, retval will always be false on entering this statement,

so it will always be false after evaluating it
Note #4: Same as #3.

So this method always returns false. I think you might be looking for something like
public boolean equals(Object o){ if (o == this) return true; else if (! (o instanceof A)) return false; else { A other = (A)o; return other.date1.equals(this.date1) && other.st.equals(this.st); } }
[ August 28, 2003: Message edited by: Ernest Friedman-Hill ]

Well, given that the typos were corrected (the hashCode() method you've shown spells "result" as "resulr" in one place, and hashCode() as hasCode() in another) it looks to me as if two objects for which my equals() method returns true should have the same hashCode() as well.
Maybe you could show us some code where you create A objects and make these comparisons, and tell us what the result is? Try to use real cut-and-pasted code rather than typed-in code, because sometimes typos can be important!

Thanks,
I actually save the A object to the database first, then
use its primary key to retrieve this object, and store it
in another variable. Then I compare them.
If I remove Date variables from my class, and use Strings,
then everything runs fine. If I use Date varibales, then I
got not equal error. I guess it is possible I am getting different
Date values from database. I will check.
regards,

Originally posted by Ernest Friedman-Hill:
Well, given that the typos were corrected (the hashCode() method you've shown spells "result" as "resulr" in one place, and hashCode() as hasCode() in another) it looks to me as if two objects for which my equals() method returns true should have the same hashCode() as well.
Maybe you could show us some code where you create A objects and make these comparisons, and tell us what the result is? Try to use real cut-and-pasted code rather than typed-in code, because sometimes typos can be important!

just another note, the Date's must be equal to the millisecond. So if at any point, your precision drops below milliseconds, then the dates will not be equal. ( ie. on the insertion into/retrieval from the database )
Jamie

Add a toString() method to print out the values.