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From "Rikesh Balan Krishnan" <RikeshBalan_Krish...@infosys.com>
Subject RE: Sorting of array lists
Date Thu, 10 Mar 2005 09:36:35 GMT
But all this methods are applicable only if the model class extends the
comparator interface.I too had a similar problem,but I was not able to
use the collection.sort because if the model class doesn't extend the
comparator interface, it will give a class cast exception.finally I had
to settle for a alofrithm where I wrote a sort method.I'm still looking
for some different method.



-----Original Message-----
From: Mark Benussi [mailto:mark_benussi@hotmail.com] 
Sent: Thursday, March 10, 2005 2:39 PM
To: 'Struts Users Mailing List'
Subject: RE: Sorting of array lists

Krishna,

The below example uses a comparator which orders a collection of objects
based on a property. You can make the criteria more complicated if you
wish.

import java.util.ArrayList;
import java.util.Collections;
import java.util.Comparator;

public class Test {

	public static void main(String[] args) {
		Test test = new Test();
	}
	public Test() {
		ArrayList arrayList = new ArrayList();
		// The plan would have probably been read and populated
from
the db
		arrayList.add(new Plan());
		arrayList.add(new Plan());
		arrayList.add(new Plan());

		Collections.sort(arrayList, new Comparator() {
			public int compare(Object object1, Object
object2) {
				return ((Plan)
object1).getTitle().compareTo(
					((Plan) object2).getTitle());
			}
		});
	}

	private class Plan {
		private String name = null;
		private String title = null;
		private String description = null;
		public String getDescription() {
			return description;
		}
		public String getName() {
			return name;
		}
		public String getTitle() {
			return title;
		}
		public void setDescription(String string) {
			description = string;
		}
		public void setName(String string) {
			name = string;
		}
		public void setTitle(String string) {
			title = string;
		}
	}
}

-----Original Message-----
From: Krishna Mohan Radhakrishnan [mailto:KrishnaMohan_R@infosys.com] 
Sent: 10 March 2005 08:35
To: Struts Users Mailing List
Subject: Sorting of array lists


Hi all,

I have a doubt regarding sorting in array List.

I have an array List  which contains array list objects of type Plan.

The Plan object contains 3 variables : plantitle ,plandescription and
planname.

I have to sort the arraylist based on the plantitle first and then based
on the plandescription.


ArrayList list = new ArrayList();
Plan planobj = null;
For (i= 1, i<=100, i++){
planObj = readPlanObjectFromDB();
list.add(planObj);

}

//?? Now how to sort it 


Private Plan readPlanObjectFromDB(){
//queries the database to return plan object

return plan;
}

I am totally confused. Even if use bubble sorting it will cause a lot of
performance issues.

Could any one please suggest me a good method?

Regards,
Krishna Mohan


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