ArrayList with Linq, Find Maximum from custome class instance

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I am having a arraylist which stored instance of my class named PointOnLine

my class definition is like

SQL

public class PointOnLine
        {
            public float degree;
            public LinkedList.Node node;
            public int countPoint;
            public override string ToString()
            {
                return Convert.ToString(degree.ToString() + "        " + countPoint.ToString());
            }
        }

I am adding approx 100 to 500 instances of above class in array list like this

arrayList.Add(objPointOnLine);
arrayList.Add(objPointOnLine1);
arrayList.Add(objPointOnLine2);

and so on

Now I want to find instance of PointOnLine having maximum value of countPoint field, from arraylist using Linq or Limbda expression.

Thanks

Posted 10-Aug-10 22:59pm

Khaniya

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#realJSOP · Answer 1 · 2010-08-10T23:40:00

Solution 1

C#

var max_value = (from item in arrayList
               select item.countPoint).Max();

Google would have helped you faster.

Posted 10-Aug-10 23:40pm

#realJSOP

v2

Comments

Khaniya 11-Aug-10 6:00am

Sorry It is not working
I think there is casting issue
It gives error

Could not find an implementation of the query pattern for source type 'System.Collections.ArrayList'. 'Select' not found. Consider explicitly specifying the type of the range variable 'item'.

Jimmanuel · Answer 2 · 2010-08-11T03:31:00

Solution 3

Why on earth are people still using ArrayList for any version of .NET 2.0 or greater? If you use a List<PointOnLine> instead then both of the previous answers will probably work.

Posted 11-Aug-10 3:31am

Jimmanuel

Comments

Dalek Dave 11-Aug-10 10:32am

Good Call

Abhishek Sur · Answer 3 · 2010-08-10T23:40:00

Solution 2

Use

arrayList.Max(a => a.countPoint);

to get the object that have Maximum countPoint.

Posted 10-Aug-10 23:40pm

Abhishek Sur

Comments

Khaniya 11-Aug-10 5:58am

thanks for your reply
but sorry to say you I could not find Max in arrayList

It shows following error

'System.Collections.ArrayList' does not contain a definition for 'Max' and no extension method 'Max' accepting a first argument of type 'System.Collections.ArrayList' could be found (are you missing a using directive or an assembly reference?)

#realJSOP · Answer 4 · 2010-08-11T05:08:00

Try this.

C#

var max_value = (from PointOnLine item in arrayList
               select item.countPoint).Max();

You've had several suggestions on how to approach your problem. Be a programmer and figure it out. Nobody here is going to sit down and write code to figure it out for you. We simply don't have the time.

The suggestion to use List instead of ArrayList will go a long way to helping you solve your issue.