WPF, C# Sorting and two-dimensional ArrayList

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I am working on a WPF, C# application.

I am wondering how I can sort an ArrayList, i.e. a text file. I have a text file called topScore.txt and have created a file reader for the topScore.txt. However I am not sure of how I would sort this ArrayList.

This is the code for the FileReader, storing the information into scoreList, which is an arrayList.

C#

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
using System.IO;

namespace TowerOfHanoi
{
    class FileReader
    {
        //Reading topScore
        static string filename1 = "topScore.txt";
        public static ArrayList readScore()
        {
            ArrayList scoreList = new ArrayList();
            //Process input file
            StreamReader sr = new StreamReader(filename1);
            String line = sr.ReadLine();
            String[] splits;
            while (line != null)
            {
                Score score = new Score();
                //Splits out parts and creates score objects
                splits = line.Split(';');
                score.name = splits[0];
                score.points = Convert.ToDouble(splits[1]);
                scoreList.Add(score);
                line = sr.ReadLine();
            }
            sr.Close();
            return scoreList;
        }

The topScore.txt contains a two dimensional information. i.e.
Mark; 1000
John; 235
Peter; 663
Sam; 345

How can I order this in terms of score. Thus so it becomes:
Mark; 1000
Peter; 663
Sam; 345
John; 235

This is just an example of how the file is structued, the file.txt is too big to order by hand. Plus new information is scores and names are entered at different stages.

There is also a class called Score, however it has an open constructor. It looks like this:

C#

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace TowerOfHanoi
{
    class Score
    {
        //encapsulated data
        public string name;
        public double points;

        //Constructor
        public Score()
        {

        }
    }
}

Posted 15-Mar-11 17:29pm

Dippler23

Updated 15-Mar-11 17:34pm

Sergey Alexandrovich Kryukov

v4

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Comments

Toli Cuturicu 16-Mar-11 16:00pm

Forget about ArrayList. Never use it again.

3 solutions

Solution 3

Don't use an ArrayList - use a generic collection. Once you've converted your code, check out this tip/trick:

A Generic Comparison Class for Collection Items[^]

Posted 16-Mar-11 8:29am

#realJSOP

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Sergey Alexandrovich Kryukov · Accepted Answer · 2011-03-15T17:46:00

Don't use ArrayList. This type is obsolete since generics were introduced in v.2.0. Why do you need all those problems with type casting?

Instead, use the generic class System.Collections.Generic.List<T>, http://msdn.microsoft.com/en-us/library/6sh2ey19.aspx[^]. For sorting use some of the Sort methods. The sorting can be done using default comparison rules (default comparer), or you can define custom comparison using custom-defined delegate of the type System.Comparison<T> or by defining a class implementing the interface System.Collections.Generic.IComparer<T>. The range sorting is also available.

Alternatively, you can use a list which is kept sorted by a key, System.Collections.Generic.SortedList<TKey, TValue>, it can be constructed using default comparer or a custom one in the form of System.Collections.Generic.IComparer<T>.

For a two-dimensional jagged array with the element type T use the list type List<List<T>>. For sorting of such thing you will certainly need a custom comparer, which is quite easy to implement.

I don't know how comparison will help you to solve the Hanoi Tower problem — there are very simple iterative and recursive algorithms, both of them, see http://en.wikipedia.org/wiki/Tower_of_Hanoi[^].

—SA

Espen Harlinn · Accepted Answer · 2011-03-16T08:25:00

Using IComparer<T>, as SAKryukov mentioned, is a good idea, and in your case it should look something like this:

C#

using System;
using System.Collections.Generic;

namespace Harlinn.CP.ScoreTest
{
    public class Score
    {
        private string name;
        private double value;

        public Score()
        { }
        public Score(string name, double value)
        { this.name = name; this.value = value; }

        public string Name
        {
            get { return name; }
            set { if (name == value) { return; } name = value; }
        }
        public double Value
        {
            get { return value; }
            set { if (this.value == value) { return; } this.value = value; }
        }
        public override string ToString()
        {
            string result = string.Format("{0} - {1}", Name, Value);
            return result;
        }
    }

    public class ScoreByNameComparer : IComparer<Score>
    {
        public int Compare(Score x, Score y)
        {
            return x.Name.CompareTo(y.Name);
        }
    }

    public class ScoreByDescendingValueComparer : IComparer<Score>
    {
        public int Compare(Score x, Score y)
        {
            return y.Value.CompareTo(x.Value);
        }
    }



    class Program
    {
        static void Main(string[] args)
        {
            List<Score> scores = new List<Score>();
            scores.AddRange(new Score[]
            { new Score("Humpty", 100.0),
                new Score("Dumpty", 54.0),
                new Score("Mary", 45.0),
                new Score("John", 1.0) });

            scores.Sort(new ScoreByDescendingValueComparer());
            Console.Out.WriteLine("By descending value:");
            foreach (Score score in scores) 
                { Console.Out.WriteLine(score.ToString()); }
            Console.Out.WriteLine();
            scores.Sort(new ScoreByNameComparer());
            Console.Out.WriteLine("By Name:");
            foreach (Score score in scores) 
                { Console.Out.WriteLine(score.ToString()); }

        }
    }
}

The program outputs the following:
By descending value:
Humpty - 100
Dumpty - 54
Mary - 45
John - 1

By Name:
Dumpty - 54
Humpty - 100
John - 1
Mary - 45

Regards
Espen Harlinn

WPF, C# Sorting and two-dimensional ArrayList

3 solutions

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