Darryl Lyons' Blog
ColdFusion, AJAX and web...
Sunday, April 17, 2005ColdFusion vs. Java: Creating an Array of Structures
As I've stated before, I am starting to learn Java. After having read a few chapters on variable types (simple vs. complex), I decided to see if I can create an Array of Structures in Java. I already know that a Structure in ColdFusion is represented as a HashTable in Java, so I thought I'd start there. It didn't take long to learn that a HashMap is now considered the replacement of the HashTable object. I was also after a way of not limiting the size of the Array, given in Java you must specify a size. In ColdFusion of course you can keep adding elements to an array, as they automatically resize. The equivelent of a resizing array/collection in Java is a Vector. Upon exploring this object however, I also found that there was a newer alternative. An ArrayList also allows you to continually add elements, and it resizes automatically. Now, I had identified the object types that I wanted to use, an ArrayList of HashMaps. I could have used a Vector of HashTables, but the only real difference is they are synchronised (and that didn't seem to matter for the purposes of my tests). ColdFusion code<cfcomponent>
<cffunction name="arrayOfStructures">
<cfscript>
var aData = ArrayNew(1);
var stItem = StructNew();
var i = 1;
for (i=1; i LTE 10; i=i+1)
{
stItem = StructNew();
stItem.name = "Item " & i;
stItem.description = "Description " & i;
ArrayAppend(aData, stItem);
}
for (i=1; i LTE ArrayLen(aData); i=i+1)
{
writeoutput(aData[i].name & " : " & aData[i].description & "<br/>");
}
</cfscript>
</cffunction>
</cfcomponent>
Java code
import java.util.*;
public class ArrayListLoop {
public static void main (String args[])
{
ArrayList<HashMap> al = new ArrayList<HashMap>();
HashMap<String, String> h = new HashMap<String, String>();
Integer i;
for (i=1; i <= 10; i++) {
h = new HashMap<String, String>();
h.put("name", "Item" + i);
h.put("description", "Description" + i);
al.add(h);
}
Iterator it = al.iterator();
while (it.hasNext())
{
// Putting (type) before "casts" it
HashMap thisMap = (HashMap) it.next();
System.out.println(thisMap.get("name") + " : " + thisMap.get("description"));
} // end while loop
} // end main() method
} // end class
By 
, at
4/18/2005 06:22:00 am
This is an interesting way of learning Java and I like it. First code it in CF and then do the same in Java, I think that ust make it a little easier.
By 
Darryl Lyons, at
4/18/2005 07:16:00 pm
Thanks. It just made sense to me to bring to another language what I have already been doing for years. It has certainly helped me grasp some of the concepts easier.
By , at
8/01/2006 12:45:00 am
what about the guaranteed or not guaranteed ordering of elements?
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