RE: Conventions for indexed properties

[Sunil Dmonte <Su...@tavant.com>]

I Thought I'd reply to my own message with our solution to this issue.
Feedback is most welcome.

Here are the changes we made:

1) We have an indexed getter and setter exactly as per the JavaBean spec
2) A non-indexed "List" getter and setter as supported by BeanUtils
3) Using our own "ExpandableArrayList" class instead of a normal ArrayList. 

The code for this class is given below (minus documentation):

*******************************************************************
import java.util.ArrayList;
import java.util.RandomAccess;
import java.util.List;
import java.io.Serializable;

public class ExpandableArrayList extends ArrayList implements List,
    RandomAccess, Cloneable, Serializable
{
  private Class beanClass;

  public ExpandableArrayList(Class classType)
  {
    super();
    beanClass = classType;
  }

  public Object set(int index, Object element)
  {
    resizeIfNecessary(index);
    return super.set(index, element);
  }

  public Object get(int index)
  {
    resizeIfNecessary(index);
    return super.get(index);
  }

  private void resizeIfNecessary(int index)
  {
    // Extend the size of the list as needed.
    if (index >= size())
    {
      int missingElements = index - size() + 1;
      for (int i = 0; i < missingElements; i++)
      {
        try
        {
          add(beanClass.newInstance());
        }
        catch (InstantiationException e)
        {
          // log and...
          throw new RuntimeException(e);
        }
        catch (IllegalAccessException e)
        {
          // log and...
          throw new RuntimeException(e);
        }
      }
    }
  }
}
*******************************************************************

> -----Original Message-----
> From: Sunil Dmonte [mailto:Sunil.Dmonte@tavant.com]
> Sent: Friday, January 23, 2004 11:38
> To: 'Struts Users Mailing List'
> Subject: RE: Conventions for indexed properties
> 
> 
> Thanks for the responses guys. Does that mean the following 
> getter (given at
> http://jakarta.apache.org/struts/faqs/indexedprops.html) is 
> incorrect? It
> doesn't seem to follow the javabean spec for indexed properties:
> 
> public java.util.List getStringIndexed(int index) { 
>         return java.util.Arrays.asList(strAry);
> }
> 
> (If it's taking an index as a parameter, why would it return 
> the whole list?
> Is this some additional functionality that BeanUtils provides?)
> 
> Regarding the 2 variants for getters and setters - which one 
> should I use?
> Both? If I use the "whole list" variant, then I can't do any 
> index checking
> to prevent an indexing exception (unless I decide to subclass 
> ArrayList and
> override the set(index, object) method). But when I introduce 
> the "indexed"
> variant, I start getting bean-related JspExceptions like 
> "JspException: No
> getter method for property .." even though the property name 
> matches up with
> the getter and setter.
> 
> Thanks for your help!
> sunil
> 
> 
> > -----Original Message-----
> > From: Craig R. McClanahan [mailto:craigmcc@apache.org]
> > Sent: Friday, January 23, 2004 11:13
> > To: Struts Users Mailing List; John D. Hume
> > Cc: Struts Users Mailing List
> > Subject: Re: Conventions for indexed properties
> > 
> > 
> > Quoting "John D. Hume" <jo...@subres.net>:
> > 
> > > I don't have a definitive guide, but here are some examples 
> > that could 
> > > be helpful.
> > > 
> > 
> > The definitive guide starts with the JavaBeans Specification:
> > 
> >   http://java.sun.com/products/javabeans/reference/api/index.html
> > 
> > you'll see that there are two variants for indexed properties 
> > -- one that has
> > the getter and setter methods taking an array, and one that 
> > has the getter and
> > setter methods taking an additional argument for the index.
> > 
> > There's lots of other useful info about what it means to be a 
> > JavaBean here as
> > well.  Just as one example, did you know that you can 
> > actually use any method
> > names you want (getFoo/setFoo is not required) if you're 
> > willing to build a
> > BeanInfo associated with your bean class?  Or that you can 
> > "hide" properties
> > from Struts (well, really from commons-beanutils) by creating 
> > a BeanInfo that
> > does not include them?
> > 
> > Craig
> > 
> > 
> > 
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