Paul,
You shouldn't keep an instance of SimpleDateFormat as
an instance variable even though you are only using
the parse method. The reason is that the
SimpleDateFormat class is not thread-safe. This is
caused by the fact that the DateFormat class isn't
threadsafe due to the fact that a value (the date
portion of calendar) used only for the duration of a
single public method (parse) in is stored as a member
variable. (This design flaw was inspired by another
design flaw of a similar
nature in Calendar, but let's not go there.)
See:
http://developer.java.sun.com/developer/bugParade/bugs/4093418.html
http://developer.java.sun.com/developer/bugParade/bugs/4228335.html
http://developer.java.sun.com/developer/bugParade/bugs/4261469.html
So to fix your code, you'd have to put it as a member
variable, thus incurring the overhead of the object
creation each time.
This problem would be very hard to uncover if it went
into production.
Regards,
Richard
--- Paul Barry <[EMAIL PROTECTED]> wrote:
> This seems to work pretty well:
>
> private Date dateOfBirth;
> private static final DateFormat dateOfBirthFormat =
> new SimpleDateFormat("MM/dd/yyyy");
>
> public Date getDateOfBirth() {
> return dateOfBirth;
> }
>
> public void setDateOfBirth(Date dateOfBirth) {
> this.dateOfBirth = dateOfBirth;
> }
>
> public String getDateOfBirthString() {
> return dateOfBirthFormat.format(dateOfBirth);
> }
>
> public void setDateOfBirthString(String
> dateOfBirthString)
> throws ParseException {
> this.dateOfBirth =
> dateOfBirthFormat.parse(dateOfBirthString);
> }
>
> And then I use dateOfBirthString as the property in
> the <html:text> tag.
> I'll also create a rule in the validator to make
> sure that
> dateOfBirthString is the right format, so the
> ParseException never happens.
>
> Christian Bollmeyer wrote:
>
> > On Friday 09 April 2004 21:19, Paul Barry wrote:
> >
> > Generally, it's a good idea to have only String
> and boolean
> > properties in an ActionForm and convert the
> information
> > gathered for further processing lateron. For
> complex
> > validations (like Dates), I usually check in
> validate() if
> > the value entered can be successfully converted
> via
> > SimpleDateFormat and do the actual conversion when
> > populating the VO bean. But you can have 2
> properties
> > in the form as well.
> >
> > HTH,
> > -- Chris.
> >
> > BTW, as such conversions are needed quite often,
> > it's a good idea to write a small utility function
> that
> > does the conversion check and put it in either
> > your BaseActionForm or some general utility class.
> >
> >
> >>Yeah, I guess I could do that. I think need 2
> properties. I would
> >>create a dateAsString property, have the form get
> and set that, and
> >>then have the getters and setters set and convert
> the actual Date.
> >>This way I can call getDate to get a Date and
> getDateAsString to get
> >>it as a formatted String.
> >>
> >>Are their other ways to handle this, so I don't
> need 2 properties?
> >>
> >>Slattery, Tim - BLS wrote:
> >>
> >>>>ActionForm has a object that has a Date property
> that I want to
> >>>>set.
> >>>>
> >>>>So I have
> >>>>
> >>>><html:text property="object.date">
> >>>>
> >>>>If I populate the that property in the Action
> like this:
> >>>>
> >>>>MyObject obj = new MyObject();
> >>>>obj.setDate(new Date());
> >>>>form.setObject(obj);
> >>>>
> >>>>The html:text tag does a toString() on the
> object.date property.
> >>>>How can I get it to display in the MM/DD/YYYY
> format instead?
> >>>>Likewise, how
> >>>>do I make it so the user can enter a date in the
> format of
> >>>>MM/DD/YYYY and have it correctly set the Date
> property?
> >>>
> >>>I'd have the getter format the Date as a string
> (use
> >>>SimpleDateFormat.format(), you can specify any of
> a wide variety of
> >>>formats). Likewise, the setter should accept a
> string and use
> >>>SimpleDateFormat.parse() to turn it into a Date.
> If parse() returns
> >>>null then the String could not be turned into a
> Date, and you need
> >>>to display an error message.
> >>>
> >>>
>
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