.Net Fundamentals - Generic Collections - ArraList - List

The .Net Framework collection provides data structures to store and manipulate collections of items as part of the System.Collections namespace.

Array lists are used to store a bunch of items together, you can store items of different data types or items of the same type:

To create a list of items of the same type in C#:
   ArrayList EndOfQuarterList = new ArrayList();
 
  EndOfQuarterList .Add("March");
  EndOfQuarterList .Add("June");
  EndOfQuarterList .Add("September");
  EndOfQuarterList .Add("December");

To create a list of items of different types in VB:

   Dim MixAndMatch as ArrayList = new ArrayList()

  MixAndMatch.Add("First Item")
  MixAndMatch.Add(10)
  MixAndMatch.Add(3.1416)

  But what if we need a more complex ArrayList? you would need to create a Generic List, this object allows easy creation and manipulation of structured data.

  For example, we need to manage financial information at end of every quarter

   C#:
    class QuarterlyInformation
    {
        private string _Name;
        private byte _Month;
        private double _Income;      
        private double _Expenses;
   
        public string Name
        {
            get { return _Name; }
            set { _Name = value; }
        }      

        public byte Month
        {
            get { return _Month; }
            set { _Month = value; }
        }      

        public double Income
        {
            get { return _Income; }
            set { _Income = value; }
        }
   
        public double Expenses
        {
            get { return _Expenses; }
            set { _Expenses = value; }
        }

        public double ProfitAndLoss()
        {
            return _Income - _Expenses;
        }

        public QuarterlyInformation(string Name, byte Month, double Income, double Expenses)
        {
            this.Name = Name;
            this.Month = Month;
            this.Income = Income;
            this.Expenses = Expenses;
        }
    }

     static void Main(string[] args)
        {
            //handle my quarterly information

            List<QuarterlyInformation> Financials = new List<QuarterlyInformation>();

            Financials.Add(new QuarterlyInformation("March", 3, 100, 50));
            Financials.Add(new QuarterlyInformation("June", 6, 500, 250));
            Financials.Add(new QuarterlyInformation("September", 9, 350, 100));
            Financials.Add(new QuarterlyInformation("December", 12, 100, 50));

            foreach (QuarterlyInformation item in Financials)
            {
                Console.WriteLine("Profit and Loss {0}:", item.ProfitAndLoss());
            }
        }
 
     
       To summarize, generic lists are a great tool to create strong typed collections of objects