ArrayList

[vicky john]

Hi,

I'm having a method which will return total number of parts and corresponding warehouse names. I've declared return type as an Arraylist.
Now, how can i retrieve both values by iterating this Arraylist??

Any help would be greately appreciated.
Thanks in advance,
vasavi.

[Jaikiran Pai]

Vicky,

I'll move this post to our JiG(B) forum, which is more appropriate for this question.

[Manuel Leiria]

How is the data being inserted in the ArrayList?Can you show some code?

[Rob Spoor]

There are three ways of iterating over any List:

// 1: using iterator()
for (Iterator i = list.iterator(); i.hasNext(); )
{
    Object o = i.next();
    // do something
}
// 2: using get
for (int i = 0, size = list.size(); i < size; i++)
{
    Object o = list.get(i);
    // do something
}
// 3: for-each loop, available since Java 5.0
for (Object o: list)
{
    // do something
}

[Campbell Ritchie]

Originally posted by Rob Prime:
There are three ways of iterating over any List:

You have forgotten the 4th way

Iterator it = myList.iterator()
while (it.hasNext())
{
   doSomethingWhichRequires(it.next());
}//end while

There are bound to be more ways, eg while loop and i++ inside the loop, but these are the well-known standard ways to do it.
[ May 12, 2008: Message edited by: Campbell Ritchie ]

[vicky john]

This is my query in DAO:
SQL_QUERY ="select count(parts.partNum),whse.whseId from CPartsVO parts,CInventoriesVO inv,CWarehouses whse
where parts.custId = " + custId +"and inv.parst =parts.partID
and whse.whseId = inv.wareHouseCD and inv.quantity > 0 GROUP BY whse.whseId";

returns result as :
count(parts.partNum) | Whse.whseId
-----------------------------------
15 | ABC
10 | XYZ etc.,

From the DAO method, i'll return Arraylist to this manager bean.
Now, from the Bean i want to retrieve these two arraylist values.

in ManagerBean ::
can i try to retrieve those two values like below? or is there any other way to get it?? please suggest..

itrPatList = list.iterator();
if(itrPatList != null) {
while(itrPatList.hasNext()) {
Object obj = (Object)itrPatList.next();

[Manuel Leiria]

Suppose you have a view object like this:

public class WhouseVO{
  private final int count;
  private final String name;
  //getters 
  public WhouseVO(int id, String name){
    this.id = id;
    this.name = name;
  }
}

and, at some point in your DAO class

List results = new ArrayList();/*From the previous examples, I'm assuming you're not using generics*/
while(rs.next()){
  results.add(new WhouseVO(rs.getInt(1), rs.getString(2));
}
//more code...
return results;//return an ArrayList filled with objects of type WhouseVO

Now, in the managed bean, just iterate to get the objects:

for(int i = 0; i < results.size(); i++){
  WhouseVO whouse = (WhouseVO)results.get(i);
  //Do what ever you want with the object whouse
}

[ May 13, 2008: Message edited by: Manuel Leiria ]

[vicky john]

Hi,

Thanks for your suggestions.

actually i don't have any VO or POJO classes which are having the
properties of whatever i retrieve from my query in DAO.
So i can't iterate it.
I could solve the problem by using the Hash map where i'm passing
one int value as a key and corresponding value as value and be able
to retrieve both from my manager bean.

Thanks alot once again

[Manuel Leiria]

Originally posted by vicky john:
Hi,

Thanks for your suggestions.

actually i don't have any VO or POJO classes which are having the
properties of whatever i retrieve from my query in DAO.
So i can't iterate it.
I could solve the problem by using the Hash map where i'm passing
one int value as a key and corresponding value as value and be able
to retrieve both from my manager bean.

Thanks alot once again

Yes you could but what if two equal counts appear?

[Rob Spoor]

Originally posted by Campbell Ritchie:
You have forgotten the 4th way

Iterator it = myList.iterator()
while (it.hasNext())
{
   doSomethingWhichRequires(it.next());
}//end while

There are bound to be more ways, eg while loop and i++ inside the loop, but these are the well-known standard ways to do it.

[ May 12, 2008: Message edited by: Campbell Ritchie ]

To me that one is equal to the for loop version.

[Campbell Ritchie]

All right, then. 3� ways