C# Enumerable Join(IEnumerable, IEnumerable, Func, Func, Func)
Description
Correlates the elements of two sequences based on matching keys. The default equality comparer is used to compare keys.
Syntax
public static IEnumerable<TResult> Join<TOuter, TInner, TKey, TResult>(
this IEnumerable<TOuter> outer,
IEnumerable<TInner> inner,/* ww w.ja v a 2s .c o m*/
Func<TOuter, TKey> outerKeySelector,
Func<TInner, TKey> innerKeySelector,
Func<TOuter, TInner, TResult> resultSelector
)
Parameters
TOuter- The type of the elements of the first sequence.TInner- The type of the elements of the second sequence.TKey- The type of the keys returned by the key selector functions.TResult- The type of the result elements.outer- The first sequence to join.inner- The sequence to join to the first sequence.outerKeySelector- A function to extract the join key from each element of the first sequence.innerKeySelector- A function to extract the join key from each element of the second sequence.resultSelector- A function to create a result element from two matching elements.
Example
The following code example demonstrates how to use Join to perform an inner join of two sequences based on a common key.
/* www . jav a 2 s. com*/
using System;
using System.Linq;
using System.Collections.Generic;
public class MainClass{
public static void Main(String[] argv){
Person magnus = new Person { Name = "A" };
Person terry = new Person { Name = "B" };
Person charlotte = new Person { Name = "C" };
Pet barley = new Pet { Name = "D", Owner = terry };
Pet boots = new Pet { Name = "E", Owner = terry };
Pet whiskers = new Pet { Name = "F", Owner = charlotte };
Pet daisy = new Pet { Name = "G", Owner = magnus };
List<Person> people = new List<Person> { magnus, terry, charlotte };
List<Pet> pets = new List<Pet> { barley, boots, whiskers, daisy };
var query =
people.Join(pets,
person => person,
pet => pet.Owner,
(person, pet) =>
new { OwnerName = person.Name, Pet = pet.Name });
foreach (var obj in query)
{
Console.WriteLine(
"{0} - {1}",
obj.OwnerName,
obj.Pet);
}
}
}
class Person{
public string Name { get; set; }
}
class Pet
{
public string Name { get; set; }
public Person Owner { get; set; }
}