In a related question. . .
can one use multiple set methods without destroying the basic concept of a
bean. . ie
private int value;
public void setValue(int value) {
this.value = value;
}
public void setValue(String value) {
this.value = Integer.parseInt(value);
}
or does this create problems for the "introspectiveness" (is that really a
word?) of the bean?
additionally, in this same case, can the getValue return a String as opposed
to an int? or is it part of the requirement that the type T (below) is the
same?
public TypeA getP()
public setP(TypeA value)
or is it possible to have:
public TypeA getP()
public setP(TypeB value)
where TypeA and TypeB are different?
Thanks yet again,
Jeff
> -----Original Message-----
> From: Karl Roberts [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, December 07, 1999 9:11 AM
> To: [EMAIL PROTECTED]
> Subject: Re: Bean constructors
>
>
> Hi,
> One of the main concepts of a bean is that it must have a
> No-argument
> constuctor. The reason for this is obvious if you consider
> that a bean is supposed
> to be a self contained bit of code that a bean box can
> manipulate like any other
> bean. So in order to make sure that all beans behave the same
> way some conventions
> were adopted, ie all methods the retrieve the bean's properies are
> public T getP() methods
> all methods to set properties are
> public setP(T value) methods
>
> In order for all beans to be loaded in the same way (without
> knowing anthing about
> a bean but it's name) it was decided that the default no
> argument constuctor
> (which contains an implicit super() ) should be used.
>
> This said it is possible to have a bean which can take
> parameters in it's
> constuctor as long as you also have a no argument constructor
> (constuctor
> overloading ) but bear in mind if you let generic bean
> loaders load your bean they
> will always use the no-argument default constructor, but you
> can indeed write a
> scriplet in your JSP to instanciate your bean (class).
>
> eg
>
> public class MyBean {
> private String name=null;
> public MyBean() {
> this.setName("World");
> }
>
> public MyBean(String name) {
> this.setName(name);
> }
>
> public String getName() {
> return(name);
> }
>
> public void setName(String name) {
> this.name=name;
> }
> }
>
> In this case if you use <jsp:useBean ...> the default
> constuctor will be used. But
> if tou use
> <% MyBean testBean = new MyBean("Karl") %>
> then the other constuctor will be used. The thing is the
> <jsp:useBean ...> tag is
> a generic bean loader and has to have a standard method of
> launching all beans.
> The only thing I can sugest is for you to write your own
> special tag so your XML
> guys don't have to get their hands dirty ;-)
>
> Karl
>
> "Bailey, Jeff A" wrote:
>
> > Hi all,
> >
> > Was just wondering if there was a way to call a constructor
> other than the
> > default one using <jsp:usebean...>
> >
> > For example,
> >
> > // Default constructor
> > MyBean() {
> > testVal = 0;
> > }
> >
> > // Something different
> > MyBean(int i) {
> > testVal = i;
> > }
> >
> > I understand I can do something like this:
> > <%
> > MyBean m = new MyBean(10);
> > %>
> >
> > but is it possible to call the constructor and pass it an
> argument (the int
> > i) while using the <jsp:usebean...>tags instead of using a
> get and set with
> > the default constructor. This is a poor example because
> setTestVal(int i)
> > could be used easily, but for what I am working on, it
> would be much easier
> > to pass arguments to the constructor and also utilize the
> <jsp:usebean....>
> > tags so that our XML guys can work with it without too much
> instruction.
> >
> > Thanks for the help
> >
> > Jeff
> >
> >
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> > FAQs on JSP can be found at:
> > http://java.sun.com/products/jsp/faq.html
> > http://www.esperanto.org.nz/jsp/jspfaq.html
>
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> http://java.sun.com/products/jsp/faq.html
> http://www.esperanto.org.nz/jsp/jspfaq.html
>
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