Here's the full annotated code (for Phone). I think the bug is that
__equalsCalc must be be reset before returning. So I marked this as red.
Please evaluate and send me your comments.
Also think of the equals evaluating to different linked lists that contain
the same data.
Lets assume
A1->A2->A3 equals B1->B2->B3
Now change the above slightly so the linked lists are circular.
A1->A2->A3 equals B1->B2->B3
^-------+ ^--------+
They are still the same, and the equals method should return true. This is
the case handled by __equalsCalc == obj
Now change the linked lists in a more devious way.
A1->A2->A3 equals B1->B2->B3->A1->A2->A3
^-------+ ^-------------------+
In this situation, the equals method should return false since the looping
is different. In the first case, the third object points back to the
initial object. In the second case, the third element points to an object
other than the initial object. This is the case handled by __equalsCalc !=
obj.
private java.lang.Object __equalsCalc = null;
public synchronized boolean equals(java.lang.Object obj) {
// Return false immediately if wrong types
if (!(obj instanceof Phone)) { __equalsCalc = null; return false;}
// Return false if other object is null
Phone other = (Phone) obj;
if (obj == null) { __equalsCalc = null; return false; }
// Return true if ==
if (this == obj) { __equalsCalc = null; return true; }
// if equalsCalc is set, then we have looped
// back to the "this" object. Since the last time through
// we set _equalsCal to the other object, return
// true if the equalsCalc == the other object (the
// the other object loops the same way) or return
// false if the equalsCalc != the other object (the other
// object does not loop the same way.)
// Stephen pointed out that we can never recurse back
// because the method is syncronized...
// or does syncronization know that I am recursing back
// in the same thread.
if (__equalsCalc != null) {
boolean rc = (_equalsCalc == obj);
__equalsCalc = null;
return rc;
}
// Flow to here indicates no recursion, so set _equalsCalc
// to the other object in-case recursion occurs in the following
code.
__equalsCalc = obj;
boolean _equals;
_equals = true &&
areaCode == other.getAreaCode() &&
((exchange==null && other.getExchange()==null) ||
(exchange!=null &&
exchange.equals(other.getExchange()))) &&
((number==null && other.getNumber()==null) ||
(number!=null &&
number.equals(other.getNumber())));
// Always reset __equalsCalc before returning.
__equalsCalc = null;
return _equals;
}
Rich Scheuerle
IBM WebSphere & Axis Web Services Development
512-838-5115 (IBM TL 678-5115)
Glen Daniels
<gdaniels@macrome To: "'[EMAIL PROTECTED]'"
<[EMAIL PROTECTED]>
dia.com> cc:
Subject: RE: Q. about equals() in WSDL
generated datatypes
12/19/2002 07:59
AM
Please respond to
axis-dev
Hi Rich!
Hm - I'm trying to imagine an example for when this would actually get
used, and having trouble coming up with one. Could you elucidate? I guess
what I'm really asking is why doesn't "if (this == obj) return true" catch
this?
--G
P.S. Nice to see you back!
> -----Original Message-----
> From: R J Scheuerle Jr [mailto:[EMAIL PROTECTED]]
> Sent: Wednesday, December 18, 2002 8:27 PM
> To: [EMAIL PROTECTED]
> Subject: Re: Q. about equals() in WSDL generated datatypes
>
>
>
> Yes __equalsCal was meant to support equals for objects that
> had direct or
> indirectly references back to the object.
>
> Rich Scheuerle
> IBM WebSphere & Axis Web Services Development
> 512-838-5115 (IBM TL 678-5115)
>
>
>
>
> "Steve Loughran"
>
> <[EMAIL PROTECTED] To:
> "axis-dev" <[EMAIL PROTECTED]>
> om> cc:
>
> Subject: Q.
> about equals() in WSDL generated datatypes
> 12/18/2002 02:38
>
> PM
>
> Please respond to
>
> axis-dev
>
>
>
>
>
>
>
>
>
> So I'm staring at the equals() method that's been generated
> for me from a
> datatype
>
> private java.lang.Object __equalsCalc = null;
>
> public synchronized boolean equals(java.lang.Object obj) {
> if (!(obj instanceof JobInfo)) return false;
> JobInfo other = (JobInfo) obj;
> if (obj == null) return false;
> if (this == obj) return true;
> if (__equalsCalc != null) {
> return (__equalsCalc == obj);
> }
> __equalsCalc = obj;
> ...tests
> __equalsCalc = null;
> return _equals;
>
>
> My q. is: what is all this __equalsCalc stuff? It implies
> that if there is
> a
> reentrant equality test then the test would return true while
> the test is
> ongoing, but since the method is synchronized, you'd be hard
> pressed to
> call
> equals() twice.
>
> Is that what the __equalsCalc is there for? To catch recursion?
>
> -steve
>
>
>
>
>
