Article source code: sorting.zip
The System.Collections namespace contains interfaces and classes that define
various collections of objects, such as lists, queues, bit arrays, hashtables
and dictionaries. You can use a collection to store objects, some collection
implementations would sort your objects by default when they are added to the
collection and some would just add them in sequence. Once the objects are added
to a collection if a custom ordered list (custom sorting) of stored objects is
required IComparer interface form System.Collections namespace and IComparable
interface from System namespace comes in handy.
An ArrayList is a Class that implements the IList interface using an array
whose size is dynamically increased as required. ArrayList.Sort method sorts
the elements in the ArrayList.
Details of ArrayList.Sort method (Overload List) (check MSDN for more info)
- Sorts the elements in the entire ArrayList using the IComparable implementation of each element.
[Visual Basic] Overloads Overridable Public Sub Sort()
[C#] public virtual void Sort();
- Sorts the elements in the entire ArrayList using the specified comparer.
[Visual Basic] Overloads Overridable Public Sub Sort(IComparer)
[C#] public virtual void Sort(IComparer);
- Sorts the elements in a section of ArrayList using the specified comparer.
[Visual Basic] Overloads Overridable Public Sub Sort(Integer, Integer, IComparer)
[C#] public virtual void Sort(int, int,IComparer);
Following is an example to sort an ArrayList object that stores CEmp object by four
different ways. The first sample uses IComparer interface implemented by a nested class
(CMySort) that is used for custom sorting.
The second example uses the IComparable interface implemented by CEmp class and a
public property to set for custom sorting
The CEmpdata class reads an XML document and creates objects of CEmp class and
stores them in an ArrayList. The ArrayList then is sorted by FirstName Ascending,
FirstName Descending, LastName Ascending and LastName Descending as defined by
the enum.
XML Document
<employees>
<employee>
<firstname>ashish</firstname>
<lastname>jaiman</lastname>
</employee>
<employee>
<firstname>jaya</firstname>
<lastname>pandey</lastname>
</employee>
<employee>
<firstname>neeraj</firstname>
<lastname>jaiman</lastname>
</employee>
<employee>
<firstname>ashutosh</firstname>
<lastname>sharma</lastname>
</employee>
<employee>
<firstname>zerman</firstname>
<lastname>billingslea</lastname>
</employee>
<employee>
<firstname>bernd</firstname>
<lastname>burkhardt</lastname>
</employee>
<employee>
<firstname>sanjeev</firstname>
<lastname>bhutt</lastname>
</employee>
<employee>
<firstname>li</firstname>
<lastname>li</lastname>
</employee>
</employees>
VB.Net implementation of sorting by using specified Comparer
Imports System
Imports System.Collections
Imports System.Xml
Public Class CEmpData
Public Enum enuSortOrder
FirstNameAsc = 0
FirstNameDesc = 1
LastNameAsc = 2
LastNameDesc = 3
End Enum
Private ArrEmp As ArrayList
Private objEmp As CEmp
Public Sub New()
InitializeData()
End Sub
Private Sub InitializeData()
Dim xmldoc As New XmlDocument()
Dim node As XmlNode
Dim objEmp As CEmp
xmldoc.Load("empdata.xml")
ArrEmp = New ArrayList()
For Each node In xmldoc.DocumentElement.ChildNodes
objEmp = New CEmp()
objEmp.FName = node.SelectSingleNode("firstname").InnerText
objEmp.LName = node.SelectSingleNode("lastname").InnerText
ArrEmp.Add(objEmp)
Next
End Sub
Public Function GetSortedEmp( _
ByVal xlngSortOrder As enuSortOrder) As String
ArrEmp.Sort(New CMySort(xlngSortOrder))
GetSortedEmp = GetData(ArrEmp)
End Function
Private Function GetData(ByVal xArrEmp As ArrayList) As String
Dim intCount As Integer
Dim strEmpData As String
For intCount = 0 To xArrEmp.Count - 1
strEmpData = strEmpData & CType(xArrEmp(intCount), _
CEmp).FName & Chr(9) & CType(xArrEmp(intCount), _
CEmp).LName & Chr(13)
Next
GetData = strEmpData
End Function
Class CMySort
Implements IComparer
Dim lngCompType As Integer
Sub New(ByVal xlngCompType As Integer)
lngCompType = xlngCompType
End Sub
Public Function Compare(ByVal x As Object, _
ByVal y As Object) As Integer Implements _
System.Collections.IComparer.Compare
Select Case lngCompType
Case enuSortOrder.FirstNameAsc
Compare = CType(x, CEmp).FName < CType(y, CEmp).FName
Case enuSortOrder.FirstNameDesc
Compare = CType(x, CEmp).FName > CType(y, CEmp).FName
Case enuSortOrder.LastNameAsc
Compare = CType(x, CEmp).LName < CType(y, CEmp).LName
Case enuSortOrder.LastNameDesc
Compare = CType(x, CEmp).LName > CType(y, CEmp).LName
Case Else
Compare = CType(x, CEmp).FName < CType(y, CEmp).FName
End Select
End Function
End Class
End Class
Public Class CEmp
Private mstrFName As String
Private mstrLName As String
Public Property FName() As String
Get
FName = mstrFName
End Get
Set(ByVal Value As String)
mstrFName = Value
End Set
End Property
Public Property LName() As String
Get
LName = mstrLName
End Get
Set(ByVal Value As String)
mstrLName = Value
End Set
End Property
End Class
|
C# implementation of sorting by using specified Comparer
using System;
using System.Collections;
using System.Xml;
public class CEmpData
{
public enum enuSortOrder{FirstNameAsc, FirstNameDesc,
LastNameAsc, LastNameDesc}
private ArrayList ArrEmp;
public CEmpData()
{
InitializeData();
}
private void InitializeData()
{
XmlDocument xmlDoc = new XmlDocument();
CEmp objEmp;
xmlDoc.Load("empdata.xml");
ArrEmp = new ArrayList();
foreach(XmlNode node in xmlDoc.DocumentElement.ChildNodes)
{
objEmp = new CEmp();
objEmp.FName = node.SelectSingleNode("firstname").InnerText;
objEmp.LName = node.SelectSingleNode("lastname").InnerText;
ArrEmp.Add (objEmp);
}
}
public string GetSortedEmp(int xlngSortOrder)
{
ArrEmp.Sort(new CMySort(xlngSortOrder));
return GetEmpData(ArrEmp);
}
private string GetEmpData(ArrayList xArrEmp)
{
string strEmpData="";
for (int intCount = 0;intCount < xArrEmp.Count;intCount++)
{
strEmpData = strEmpData + ((CEmp)xArrEmp[intCount]).FName +
"\t" + ((CEmp)xArrEmp[intCount]).LName + "\n";
}
return strEmpData;
}
class CMySort:IComparer
{
private int intCompType;
public CMySort(int sortOrder)
{
intCompType = sortOrder;
}
public int Compare(object x,object y)
{
switch(intCompType)
{
case (int)enuSortOrder.FirstNameAsc:
return ((CEmp)x).FName.CompareTo(((CEmp)y).FName);
case (int)enuSortOrder.FirstNameDesc:
return ((CEmp)y).FName.CompareTo(((CEmp)x).FName);
case (int)enuSortOrder.LastNameAsc:
return ((CEmp)x).LName.CompareTo(((CEmp)y).LName);
case (int)enuSortOrder.LastNameDesc:
return ((CEmp)y).LName.CompareTo(((CEmp)x).LName);
default:
return ((CEmp)x).FName.CompareTo(((CEmp)y).FName);
}
}
}
}
using System;
public class CEmp
{
private string mstrFName;
private string mstrLName;
public string FName
{
get
{
return mstrFName;
}
set
{
mstrFName = value;
}
}
public string LName
{
get
{
return mstrLName;
}
set
{
mstrLName = value;
}
}
} |
VB.Net implementation of sorting by using the IComparable interface
Imports System.Xml
Public Class CEmpData
Private objEmp As CEmp
Private ArrEmp As ArrayList
Public Sub New()
InitializeData()
End Sub
Private Sub InitializeData()
Dim xmldoc As New XmlDocument()
Dim node As XmlNode
Dim objEmp As CEmp
xmldoc.Load("empdata.xml")
ArrEmp = New ArrayList()
For Each node In xmldoc.DocumentElement.ChildNodes
objEmp = New CEmp()
objEmp.FName = node.SelectSingleNode("firstname").InnerText
objEmp.LName = node.SelectSingleNode("lastname").InnerText
ArrEmp.Add(objEmp)
Next
End Sub
Public Function GetSortedEmp(ByVal xblnSortOrder As Integer) As String
CEmp.SortMethod = xblnSortOrder
ArrEmp.Sort()
GetSortedEmp = GetData(ArrEmp)
End Function
Private Function GetData(ByVal xArrEmp As ArrayList) As String
Dim lngCount As Long
Dim strEmpData As String
For lngCount = 0 To xArrEmp.Count - 1
strEmpData = strEmpData & xArrEmp(lngCount).fname & Chr( _
9) & xArrEmp(lngCount).lname & Chr(13)
Next
GetData = strEmpData
End Function
End Class
Imports System
Public Class CEmp
Implements IComparable
Public Enum enuSortOrder
FirstNameAsc = 0
FirstNameDesc = 1
LastNameAsc = 2
LastNameDesc = 3
End Enum
Private Shared mintSortOrder As Integer
Private mstrFName As String
Private mstrLName As String
Public Property FName() As String
Get
FName = mstrFName
End Get
Set(ByVal Value As String)
mstrFName = Value
End Set
End Property
Public Property LName() As String
Get
LName = mstrLName
End Get
Set(ByVal Value As String)
mstrLName = Value
End Set
End Property
Public Function CompareTo( _
ByVal obj As Object) As Integer Implements IComparable.CompareTo
Select Case mintSortOrder
Case enuSortOrder.FirstNameAsc
CompareTo = Me.FName < CType(obj, CEmp).FName
Case enuSortOrder.FirstNameDesc
CompareTo = Me.FName > CType(obj, CEmp).FName
Case enuSortOrder.LastNameAsc
CompareTo = Me.LName < CType(obj, CEmp).LName
Case enuSortOrder.LastNameDesc
CompareTo = Me.LName > CType(obj, CEmp).LName
Case Else
CompareTo = Me.FName < CType(obj, CEmp).FName
End Select
End Function
Public Shared Property SortMethod() As enuSortOrder
Get
SortMethod = mintSortOrder
End Get
Set(ByVal Value As enuSortOrder)
mintSortOrder = Value
End Set
End Property
End Class
|
C# implementation of sorting by using the IComparable implementation
using System;
using System.Collections;
using System.Xml;
public class CEmpData
{
private ArrayList ArrEmp;
public CEmpData()
{
InitializeData();
}
private void InitializeData()
{
XmlDocument xmlDoc = new XmlDocument();
CEmp objEmp;
xmlDoc.Load("empdata.xml");
ArrEmp = new ArrayList();
foreach(XmlNode node in xmlDoc.DocumentElement.ChildNodes)
{
objEmp = new CEmp();
objEmp.FName = node.SelectSingleNode("firstname").InnerText;
objEmp.LName = node.SelectSingleNode("lastname").InnerText;
ArrEmp.Add (objEmp);
}
}
public string GetSortedEmp(int xlngSortOrder)
{ CEmp.SortOrder = xlngSortOrder;
ArrEmp.Sort();
return GetEmpData(ArrEmp);
}
private string GetEmpData(ArrayList xArrEmp)
{
string strEmpData="";
for (int intCount = 0;intCount < xArrEmp.Count;intCount++)
{
strEmpData = strEmpData + ((CEmp)xArrEmp[intCount]).FName +
"\t" + ((CEmp)xArrEmp[intCount]).LName + "\n";
}
return strEmpData;
}
}
using System;
public class CEmp:System.IComparable
{
public enum enuSortOrder{FirstNameAsc, FirstNameDesc,
LastNameAsc, LastNameDesc}
public static int mintSortOrder;
private string mstrFName;
private string mstrLName;
public string FName
{
get
{
return mstrFName;
}
set
{
mstrFName = value;
}
}
public string LName
{
get
{
return mstrLName;
}
set
{
mstrLName = value;
}
}
public static int SortOrder
{
get
{
return mintSortOrder;
}
set
{
mintSortOrder = value;
}
}
public int CompareTo(object obj)
{
switch (mintSortOrder)
{
case (int)enuSortOrder.FirstNameAsc:
return this.FName.CompareTo(((CEmp)obj).FName);
case (int)enuSortOrder.FirstNameDesc:
return (((CEmp)obj).FName).CompareTo(this.FName);
case (int)enuSortOrder.LastNameAsc:
return this.LName.CompareTo(((CEmp)obj).LName);
case (int)enuSortOrder.LastNameDesc:
return (((CEmp)obj).LName).CompareTo(this.LName);
default:
return this.FName.CompareTo(((CEmp)obj).FName);
}
}
} |