Need help on How to do sorting on table column header

[Anjali Abraham <an...@aztec.soft.net>]

Hi All,
            I have a table in my page, with all its column header's to be of
link type, and when clicking on those column header link's I need to do
sorting on that particular column data of the table using tapestry. I use
tapestry4.0v.
 
Please respond with solutions.....
Thanks in advance,
 
Regards,
Anjali
 

Re: Need help on How to do sorting on table column header

[Will Scheidegger <wi...@mac.com>]

I've implemented a rather complex setup, which is very easy to use 
though. In my page which contains the list, I have a method 
"sortByAttributeList(...)":

	public void sortByAttributeList(String[] attributes, int 
sortOrderOperator) {
		ArrayList sortOrders = new ArrayList();
		for (int i=0; i<attributes.length; i++) {
			sortOrders.add(new SortOrder(attributes[i], sortOrderOperator));
		}
		Comparator sortOrder;
		if (sortOrders.size() > 1) {
			sortOrder = new ComplexSortOrder(sortOrders);
		} else if (sortOrders.size() > 0) {
			sortOrder = (SortOrder) sortOrders.get(0);
		} else {
			sortOrder = null;
		}
		if (sortOrder != null) {
			getListHandler().setSortOrder(sortOrder);
			getListHandler().sort();
		}
	}

The top part of this method converts the list of attributes and the 
sort order into a java.util.Comparator object (i.e. a custom class 
implementing the java.util.Comparator interface). This Comparator is 
then applied to the list in the bottom part of the method

The ListHandler class (see getListHandler()) simply encapsulates the 
list to display and adds a few additional features (filtering, sorting, 
pagination). It's sort() method does  the following:

	public void sort() {
		if (sortOrder != null) {
			batchIndex = 1;
			displayedObjects = null;
			Collections.sort(getAllObjects(), sortOrder);
		}
	}

It checks for a sort order and sorts the list accordingly using the 
java.util.Collections class.

So as a management summary:
1. Create an object implementing the java.util.Comparator interface 
which compares the attributes you would like to sort.
2. Apply this object to the list unsing the 
java.util.Collections.sort() method.

Good luck.

-Will

On 15.09.2005, at 07:53, Anjali Abraham wrote:

> Hi All,
>             I have a table in my page, with all its column header's to 
> be of
> link type, and when clicking on those column header link's I need to do
> sorting on that particular column data of the table using tapestry. I 
> use
> tapestry4.0v.
>
> Please respond with solutions.....
> Thanks in advance,
>
> Regards,
> Anjali
>


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