Getting size of an array thru EL

[Varun Ratra]

Hi All,

Can we get a size of an array by using EL? Or, using scriptlet is the only way to get it, when constructing a JSP?

regards,

[Marc Peabody]

Great question.

EL expects objects to abide by Bean Law. But some of our most common Java classes don't follow the rules: String.length(), *Arrays*.length, and the Collection classes.size().

It's likely that your collection/array/string exists in a bean, whether you are keeping it in a Struts ActionForm or just a plain ol' Transfer Object. That means you can add a method to your bean for retrieving size of these items.

An example is given here, and yes it does seem "kludgy".

[Marc Peabody]

Oh yes, and as Satou mentions here, you can use fn:length as long as you are working with J2EE 1.4. Here's a decent Sun tutorial on how to use it.

The "kludgy" way is for 1.3, which you may end up having to implement in the real world. The entire world isn't using 1.4 yet and you have to make do with whatever you've got. :roll:

[Varun Ratra]

Hi Marc,

Thanks a lot for your help.

regards,

[Arvind Sampath]

Marc,

How about having a generic static utility function, say getLength(Object) in some utility class which will return the size of the collection/array/String ?

public static long getLength(Object obj)
      {
long size=-1;
if(obj instanceof Object[])
size=(Object[])str).length;
else if(obj instanceof String)
size=((String)obj).length();
else if(obj instanceof List)
size=((List)obj).size();
return size;
        } 

This function can be registerd in a tld flle and could be invoked from the jsp using EL.


Sounds decent...doesnt it ? :-)

Cheers,
Arvind