Class with IComparable and IComparer
using System;
using System.Collections;
public class MainClass
{
public static int Main(string[] args)
{
Employee[] empList = new Employee[5];
empList[0] = new Employee(123, "R");
empList[1] = new Employee(6, "M");
empList[2] = new Employee(6, "V");
empList[3] = new Employee(13, "N");
empList[4] = new Employee(6, "C");
if(empList[0] < empList[4])
Console.WriteLine("empList[0] < empList[4]");
else
Console.WriteLine("empList[0] >= empList[4]");
return 0;
}
}
public class Employee : IComparable
{
private class SortByEmployeemNameHelper : IComparer
{
public SortByEmployeemNameHelper(){}
int IComparer.rupare(object o1, object o2)
{
Employee t1 = (Employee)o1;
Employee t2 = (Employee)o2;
return String.rupare(t1.EmployeemName, t2.EmployeemName);
}
}
private int EmployeeID;
private string petName;
// properties.
public int ID
{
get{return EmployeeID;}
set{EmployeeID = value;}
}
public string EmployeemName
{
get{return petName;}
set{petName = value;}
}
// Constructor set.
public Employee(){}
public Employee(int id, string name){
this.EmployeeID = id;
this.petName = name;
}
// IComparable implementation.
int IComparable.rupareTo(object o)
{
Employee temp = (Employee)o;
if(this.EmployeeID > temp.EmployeeID)
return 1;
if(this.EmployeeID < temp.EmployeeID)
return -1;
else
return 0;
}
// Property to return the SortByEmployeemName comparer.
public static IComparer SortByEmployeemName{
get { return (IComparer)new SortByEmployeemNameHelper(); }
}
public static bool operator < (Employee c1, Employee c2)
{
IComparable itfComp = (IComparable)c1;
return (itfComp.rupareTo(c2) < 0);
}
public static bool operator > (Employee c1, Employee c2)
{
IComparable itfComp = (IComparable)c1;
return (itfComp.rupareTo(c2) > 0);
}
public static bool operator <= (Employee c1, Employee c2)
{
IComparable itfComp = (IComparable)c1;
return (itfComp.rupareTo(c2) <= 0);
}
public static bool operator >= (Employee c1, Employee c2)
{
IComparable itfComp = (IComparable)c1;
return (itfComp.rupareTo(c2) >= 0);
}
}empList[0] >= empList[4]
IComparer as a Property
using System;
using System.Collections;
public class Employee: IComparable
{
public Employee(string name, int id)
{
this.name = name;
this.id = id;
}
int IComparable.rupareTo(object obj)
{
Employee emp2 = (Employee) obj;
if (this.id > emp2.id)
return(1);
if (this.id < emp2.id)
return(-1);
else
return(0);
}
public static IComparer SortByName
{
get
{
return((IComparer) new SortByNameClass());
}
}
public static IComparer SortById
{
get
{
return((IComparer) new SortByIdClass());
}
}
public override string ToString()
{
return(name + ":" + id);
}
class SortByNameClass: IComparer
{
public int Compare(object obj1, object obj2)
{
Employee emp1 = (Employee) obj1;
Employee emp2 = (Employee) obj2;
return(String.rupare(emp1.name, emp2.name));
}
}
class SortByIdClass: IComparer
{
public int Compare(object obj1, object obj2)
{
Employee emp1 = (Employee) obj1;
Employee emp2 = (Employee) obj2;
return(((IComparable) emp1).rupareTo(obj2));
}
}
string name;
int id;
}
class MainClass
{
public static void Main()
{
Employee[] arr = new Employee[4];
arr[0] = new Employee("A", 1);
arr[1] = new Employee("B", 2);
arr[2] = new Employee("C", 4);
arr[3] = new Employee("D", 3);
Array.Sort(arr, Employee.SortByName);
Console.WriteLine("employees is now sorted by name");
foreach (Employee emp in arr)
Console.WriteLine("Employee: {0}", emp);
Array.Sort(arr, Employee.SortById);
Console.WriteLine("employees is now sorted by id");
foreach (Employee emp in arr)
Console.WriteLine("Employee: {0}", emp);
ArrayList arrList = new ArrayList();
arrList.Add(arr[0]);
arrList.Add(arr[1]);
arrList.Add(arr[2]);
arrList.Add(arr[3]);
arrList.Sort(Employee.SortByName);
foreach (Employee emp in arrList)
Console.WriteLine("Employee: {0}", emp);
arrList.Sort(); // default is by id
foreach (Employee emp in arrList)
Console.WriteLine("Employee: {0}", emp);
}
}employees is now sorted by name
Employee: A:1
Employee: B:2
Employee: C:4
Employee: D:3
employees is now sorted by id
Employee: A:1
Employee: B:2
Employee: D:3
Employee: C:4
Employee: A:1
Employee: B:2
Employee: C:4
Employee: D:3
Employee: A:1
Employee: B:2
Employee: D:3
Employee: C:4
Use IComparer
using System;
using System.Collections;
// Create an IComparer for Product objects.
class ProductComparer : IComparer {
// Implement the IComparable interface.
public int Compare(object obj1, object obj2) {
Product a, b;
a = (Product) obj1;
b = (Product) obj2;
return a.name.rupareTo(b.name);
}
}
class Product {
public string name;
double cost;
int onhand;
public Product(string n, double c, int h) {
name = n;
cost = c;
onhand = h;
}
public override string ToString() {
return
String.Format("{0,-10}Cost: {1,6:C} On hand: {2}",
name, cost, onhand);
}
}
class IComparerDemo {
public static void Main() {
ProductComparer comp = new ProductComparer();
ArrayList inv = new ArrayList();
// Add elements to the list
inv.Add(new Product("A", 5.5, 3));
inv.Add(new Product("B", 8.9, 2));
inv.Add(new Product("C", 3.0, 4));
inv.Add(new Product("D", 1.8, 8));
Console.WriteLine("Product list before sorting:");
foreach(Product i in inv) {
Console.WriteLine(" " + i);
}
Console.WriteLine();
// Sort the list using an IComparer.
inv.Sort(comp);
Console.WriteLine("Product list after sorting:");
foreach(Product i in inv) {
Console.WriteLine(" " + i);
}
}
}Product list before sorting:
A Cost: $5.50 On hand: 3
B Cost: $8.90 On hand: 2
C Cost: $3.00 On hand: 4
D Cost: $1.80 On hand: 8
Product list after sorting:
A Cost: $5.50 On hand: 3
B Cost: $8.90 On hand: 2
C Cost: $3.00 On hand: 4
D Cost: $1.80 On hand: 8
