C# Online Compiler | .NET Fiddle

<no name> by Anonymous

using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
					
public class Program
{
	public static void Main()
	{
		var china = new Country { Name = "China", Alias = "china" };
		var japan = new Country { Name = "Japan", Alias = "japan" };
		var korea = new Country { Name = "Korea", Alias = "korea" };
		var malaysia = new Country { Name = "Malaysia", Alias = "malaysia" };
		
		List<Partner> partners = new List<Partner> {
			new Partner(){ Name = "A", Country = china },
			new Partner(){ Name = "B", Country = japan },
			new Partner(){ Name = "C", Country = korea },
			new Partner(){ Name = "D", Country = korea },
			new Partner(){ Name = "E", Country = japan },
			new Partner(){ Name = "F", Country = malaysia },
			new Partner(){ Name = "G", Country = china },
			new Partner(){ Name = "H", Country = japan },
			new Partner(){ Name = "I", Country = japan },
			new Partner(){ Name = "J", Country = korea },
			new Partner(){ Name = "K", Country = china },
		};
		
		var listSort = partners.GroupBy(x => x.Country);
		
		foreach(var partnerGroup in listSort) {
			Console.WriteLine(partnerGroup.Key.Name);
			
			foreach(var partner in partnerGroup) {
				Console.WriteLine(partner.Name);
			}
		}
	}
}

public class Partner
{
	public string Name { get; set; }
	public Country Country { get; set; }
}

public class Country
{
	public string Name { get; set; }
	public string Alias { get;set; }
}

​x
 
using System;
using System.Linq;
using System.Collections;
using System.Collections.Generic;
                    
public class Program
{
    public static void Main()
    {
        var china = new Country { Name = "China", Alias = "china" };
        var japan = new Country { Name = "Japan", Alias = "japan" };
        var korea = new Country { Name = "Korea", Alias = "korea" };
        var malaysia = new Country { Name = "Malaysia", Alias = "malaysia" };
        
        List<Partner> partners = new List<Partner> {
            new Partner(){ Name = "A", Country = china },
            new Partner(){ Name = "B", Country = japan },
            new Partner(){ Name = "C", Country = korea },
            new Partner(){ Name = "D", Country = korea },
            new Partner(){ Name = "E", Country = japan },
            new Partner(){ Name = "F", Country = malaysia },
            new Partner(){ Name = "G", Country = china },
            new Partner(){ Name = "H", Country = japan },
            new Partner(){ Name = "I", Country = japan },
            new Partner(){ Name = "J", Country = korea },
            new Partner(){ Name = "K", Country = china },
        };
        
        var listSort = partners.GroupBy(x => x.Country);
        
        foreach(var partnerGroup in listSort) {
            Console.WriteLine(partnerGroup.Key.Name);
            
            foreach(var partner in partnerGroup) {
                Console.WriteLine(partner.Name);
            }
        }
    }
}
​
public class Partner
{
    public string Name { get; set; }
    public Country Country { get; set; }
}
​
public class Country
{
    public string Name { get; set; }
    public string Alias { get;set; }
}

Roslyn 2.0 Compiler; Environment version: 4.0.30319.42000

<?xml version="1.0" encoding="utf-16"?>
<data xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" someattributea="" someattributeb="" someattributec="" ExtraAttr="" p1:someattributec="namespace attr" xmlns:p1="http://SomeTestNamespace.com" />
<?xml version="1.0" encoding="utf-16"?>
<data xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" someattributea="replacement value for Someattributea" someattributec="" ExtraAttr="" p1:someattributec="namespace attr" xmlns:p1="http://SomeTestNamespace.com" />

Testing a list of Data.
<?xml version="1.0" encoding="utf-16"?>
<DataList xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <DataItem someattributea="" someattributeb="" someattributec="" ExtraAttr="" p1:someattributec="namespace attr" xmlns:p1="http://SomeTestNamespace.com" xmlns="https://Test Namespace" />
  <DataItem someattributea="" someattributeb="" someattributec="" ExtraAttr="" p1:someattributec="namespace attr" xmlns:p1="http://SomeTestNamespace.com" xmlns="https://Test Namespace" />
</DataList>
<?xml version="1.0" encoding="utf-16"?>
<DataList xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <DataItem someattributea="" someattributeb="" someattributec="" ExtraAttr="" p1:someattributec="namespace attr" xmlns:p1="http://SomeTestNamespace.com" xmlns="https://Test Namespace" />
  <DataItem someattributea="" someattributeb="" someattributec="" ExtraAttr="" p1:someattributec="namespace attr" xmlns:p1="http://SomeTestNamespace.com" xmlns="https://Test Namespace" />
</DataList>

Last Run:	6:50:01 pm
Compile:	1.125s
Execute:	0.29s
Memory:	2.40Mb
CPU:	0.547s

View IL Code