This should always give you the equivalent of Object's toString method:
Integer.toHexString(System.identityHashCode(obj)).
If anything gets added, I'd rather see something like what's used in
java.awt.Component. The toString method is implemented like:
public String toString() {
return getClass().getName() + "[" + paramString() + "]";
}
Then Component has its own implementation of the paramString method:
protected String paramString() {
...
return str;
}
Finally, subclasses invoke super.paramString and add their own information:
protected String paramString() {
return super.paramString() + ...;
}
The implementation of paramString for ActionForm should probably just look
like:
protected String paramString() {
return "";
}
;-) About the only thing worth adding might be the ActionServlet reference. In
the end, all this is doing is providing a convenient hook for subclasses. The
decision about what information to include is still the responsibility of the
subclasses (as it should be).
Note that DynaActionForm already provides its own implementation of toString,
which is inherited by DynaValidatorForm and DynaValidatorActionForm. So,
DynaActionForm could then be changed to remove its toString method and provide
a paramString method instead:
protected String paramString() {
StringBuffer buff = new StringBuffer();
if (!this.dynaValues.isEmpty()) {
buff.append(", ");
for (Iterator iter = this.dynaValues().entrySet().iterator();
iter.hasNext();) {
Map.Entry entry = (Map.Entry)iter.next();
buff.append(entry.getKey()).append("=");
Object propValue = entry.getValue();
if (propValue == null) {
buff.append("<NULL>");
} else if (propValue.getClass().isArray()) {
buff.append("[");
int length = Array.getLength(propValue);
for (int i = 0; i < length; i++) {
buff.append(Array.get(propValue, i));
if (i < (length - 1)) {
buff.append(", ");
}
}
buff.append("]");
} else {
buff.append(propValue);
}
if (iter.hasNext()) {
buff.append(", ");
}
}
}
return super.paramString() +
", dynaClass=" + getDynaClass().getName() +
buff.toString();
}
Quoting [EMAIL PROTECTED]:
> Frank,
>
> I also had to go a long way until I found this approach. It actually came to
> me when I saw in my project many data objects (= java beans) were generated
> using UML tools that did not care about the toString() method my way. Next I
> saw Castor XML/JAXB and JDO code generation, and finally had to decide that a
> common base class or implementing each and every toString method is not the
> solution.
>
> With the static method I can apply my toString implementation to any object
> that comes along - just what you need for debugging. I just wonder why the
> Apache commons-beanutils does not provide such a method, and someone
> mentioned it might be in commons-lang, but I could not find that either.
>
> Hiran
>
> -----------------------------------------
> Hiran Chaudhuri
> SAG Systemhaus GmbH
> Elsenheimer Straße 11
> 80867 München
> Phone +49-89-54 74 21 34
> Fax +49-89-54 74 21 99
>
>
>
>
> > -----Original Message-----
> > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
> > Sent: Donnerstag, 7. Oktober 2004 14:22
> > To: [EMAIL PROTECTED]
> > Subject: RE: Proposed Action base class change
> >
> > Another fair point. :)
> >
> > Well, that's the reason I put the idea out there... I can't
> > think of every possible angle to look at it from... If I
> > thought I could, I wouldn't need to solicit opinions in the
> > first place.
> >
> > Kind of depressing though... I'm trying to contribute, but so
> > far all my ideas have been shot down (but for good reasons,
> > so I'm not bitter about it). Just have to keep trying I suppose. :)
> >
> > --
> > Frank W. Zammetti
> > Founder and Chief Software Architect
> > Omnytex Technologies
> > http://www.omnytex.com
> >
> > On Thu, October 7, 2004 8:56 am, [EMAIL PROTECTED] said:
> > > Hi, Frank.
> > >
> > > I do not agree. While in most cases it is desireable to see
> > inside a
> > > bean (hence I created my
> > > public static String toString(Object bean) method),
> > there are times
> > > when I just have to make sure a bean is not just equal but the same
> > > instance.
> > > The java.lang.Object.toString() methods allows me to that quite
> > > quickly as the memory address is printed.
> > >
> > > Unless you have another way to provide that information, I'd rather
> > > stick with the default toString() plus some utility
> > toString(Object)
> > > method. The impact for you is not too much. What you code so far is:
> > > log.debug("mybean="+mybean);
> > > and you'd have to change that to
> > > log.debug("mybean="+BeanUtil.toString(mybean));
> > > which will allow you to either see the memory address or
> > the contents,
> > > whatever you prefer.
> > >
> > > Hiran
> > >
> > > -----------------------------------------
> > > Hiran Chaudhuri
> > > SAG Systemhaus GmbH
> > > Elsenheimer Stra?e 11
> > > 80867 M?nchen
> > > Phone +49-89-54 74 21 34
> > > Fax +49-89-54 74 21 99
> > >
> > >
> > >
> > >
> > >> -----Original Message-----
> > >> From: Frank W. Zammetti [mailto:[EMAIL PROTECTED]
> > >> Sent: Donnerstag, 7. Oktober 2004 13:43
> > >> To: Struts Developers List
> > >> Subject: Re: Proposed Action base class change
> > >>
> > >> Hi Niall,
> > >>
> > >> I certainly agree it would not be possible to satisfy
> > everyone, but
> > >> seeing as the intrinsic toString() is all but useless (and
> > people do
> > >> generally expect that to be the case with many classes),
> > why not give
> > >> an implementation that is of at least some use to some people?
> > >> Surely it would be better than what you get now? Obviously it's
> > >> something many people will override, and that's of course
> > the whole
> > >> point of inheritance. But providing even a slightly more useful
> > >> default implementation (and maybe telling people it's a
> > basic default
> > >> implementation so as to try and keep the flood of bugzilla
> > requests
> > >> to a
> > >> minimum) seems to me like a good idea.
> > >>
> > >> I can't address your point about dynabeans because I haven't used
> > >> them enough to be able to intelligently comment (which is to say I
> > >> haven't used them at all! :) )... I wouodn't imagine some basic
> > >> implementation would be too tough for them as well.
> > >>
> > >> In any case, I will look at the toString builders you mentioned...
> > >> I've come to really like using the commons packages and I try to
> > >> whenever I can. This would be a good case I think, if it
> > doesn't get
> > >> added as I proposed. I already have an ActionHelpers class with a
> > >> bunch of similarly-themed static methods for use from Actions, so
> > >> maybe it's time to do so for forms as well.
> > >>
> > >> --
> > >> Frank W. Zammetti
> > >> Founder and Chief Software Architect
> > >> Omnytex Technologies
> > >> http://www.omnytex.com
> > >>
> > >> Niall Pemberton wrote:
> > >> > Frank,
> > >> >
> > >> > For me it wouldn't be any use unless it also handled
> > >> DynaBeans. Even
> > >> > then I'd end up overriding it because I have some
> > formatting utils
> > >> > which do dates, arrays and collections. Seems to me if
> > we put it in
> > >> > then we would end up with a monster trying to satisy
> > >> everyones needs
> > >> > and forever dealing with bugzilla requests for
> > enhacements (someone
> > >> > would want an i18n version!) - all just for debugging.
> > >> >
> > >> > The easiest thing is to just put all that code into a
> > >> utility method -
> > >> > that way its only a one liner in the toString() - even
> > >> better if you
> > >> > have your own "base" ActionForm that all you others derive
> > >> from, then
> > >> > its only in one place.
> > >> >
> > >> > Also, there are a set of "toString" builders in commons
> > >> lang which you
> > >> > might like to use - including a reflection one like yours:
> > >> >
> > >> >
> > >>
> > http://jakarta.apache.org/commons/lang/api/org/apache/commons/lang/bu
> > >> i
> > >> > lder/package-summary.html
> > >> >
> > >>
> > http://jakarta.apache.org/commons/lang/api/org/apache/commons/lang/bu
> > >> i
> > >> > lder/ReflectionToStringBuilder.html
> > >> >
> > >> > Niall
> > >> >
> > >> > ----- Original Message -----
> > >> > From: "Frank W. Zammetti" <[EMAIL PROTECTED]>
> > >> > To: "Struts Developer" <[EMAIL PROTECTED]>
> > >> > Sent: Thursday, October 07, 2004 4:29 AM
> > >> > Subject: Re: Proposed Action base class change
> > >> >
> > >> >
> > >> >
> > >> >>Obviously I made a typo in the subject... this applies to the
> > >> >>ActionForm base class.
> > >> >>
> > >> >>Did anyone have any comment on this? I've noticed a lack
> > >> of activity
> > >> >>on the list lately...
> > >> >>
> > >> >>
> > >> >>>Hello all...
> > >> >>>
> > >> >>>I find myself all the time overloading toString() of my
> > >> ActionForms
> > >> >>>for
> > >> >
> > >> > debugging
> > >> >
> > >> >>>purposes, so I can easily dump the current state of the
> > object. I
> > >> >>>had
> > >> >
> > >> > been doing
> > >> >
> > >> >>>this for each ActionForm class, specifically for it, but
> > >> it ocurrs to
> > >> >>>me
> > >> >
> > >> > that a
> > >> >
> > >> >>>general-purpose reflection-based approach would be better.
> > >> >>>
> > >> >>>I'd like to propose adding this functionality to the
> > >> ActionForm base
> > >> >
> > >> > class. Here's
> > >> >
> > >> >>>the code I propose adding:
> > >> >>>
> > >> >>>import java.lang.reflect.Field;
> > >> >>>public static final AVERAGE_FIELD_SIZE = 25; public String
> > >> toString()
> > >> >>>{
> > >> >>> String str = "";
> > >> >>> StringBuffer sb = null;
> > >> >>> try {
> > >> >>> Field[] fields = this.getClass().getDeclaredFields();
> > >> >>> sb = new StringBuffer(fields.length * AVERAGE_FIELD_SIZE);
> > >> >>> for (int i = 0; i < fields.length; i++) {
> > >> >>> if (sb.length() > 0) { sb.append(", "); }
> > >> >>> sb.append(fields[i].getName() + "=" +
> > fields[i].get(this));
> > >> >>> }
> > >> >>> str = sb.toString().trim();
> > >> >>> } catch (Exception e) {
> > >> >>> str = "Exception in ActionForm.toString() : " + e;
> > >> >>> }
> > >> >>> return str;
> > >> >>>}
> > >> >>>
> > >> >>>The value of AVERAGE_FIELD_SIZE is a matter of debate,
> > and it's of
> > >> >
> > >> > course impossible
> > >> >
> > >> >>>to come up with a real value, so something reasonable is
> > >> the answer.
> > >> >>>25
> > >> >
> > >> > struck me
> > >> >
> > >> >>>as a decent starting point.
> > >> >>>
> > >> >>>What does everyone think? I find this functionality to be very
> > >> >>>useful
> > >> >
> > >> > in my work,
> > >> >
> > >> >>>and I suspect others may as well. The code doesn't add any
> > >> >>>dependencies
> > >> >
> > >> > outside
> > >> >
> > >> >>>J2SE, and it's certainly simple enough as to not be
> > >> particularly risky.
> > >> >>>
> > >> >>>Thanks all!
> > >> >>>
> > >> >>>Frank W. Zammetti
> > >> >>>Founder and Chief Software Architect Omnytex Technologies
> > >> >>>http://www.omnytex.com
--
Kris Schneider <mailto:[EMAIL PROTECTED]>
D.O.Tech <http://www.dotech.com/>
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