不使用LINQto對象的區別class Program{
static void Main(string[] args)
{
List<Book> books = new List<Book>
{
new Book
{
Name="C# in Depth",
Authors = new List<Author>
{
new Author
{
FirstName = "Jon", LastName="Skeet"
},
new Author
{
FirstName = "Jon", LastName="Skeet"
},
}
},
new Book
{
Name="LINQ in Action",
Authors = new List<Author>
{
new Author
{
FirstName = "Fabrice", LastName="Marguerie"
},
new Author
{
FirstName = "Steve", LastName="Eichert"
},
new Author
{
FirstName = "Jim", LastName="Wooley"
},
}
},
};
var temp = books.SelectMany(book => book.Authors).Distinct();
foreach (var author in temp)
{
Console.WriteLine(author.FirstName + " " + author.LastName);
}
Console.Read();
}}public class Book{
public string Name { get; set; }
public List<Author> Authors { get; set; }}public class Author{
public string FirstName { get; set; }
public string LastName { get; set; }
public override bool Equals(object obj)
{
return true;
//if (obj.GetType() != typeof(Author)) return false;
//else return ((Author)obj).FirstName == this.FirstName && ((Author)obj).FirstName == this.LastName;
}}這是基于“LINQ in Action”中的一個例子。清單4.16。這印了喬恩·斯基特兩次。為什么？我甚至在Author類中嘗試過重寫等于方法。仍然不同似乎不起作用。我遺漏了什么？
3 回答
蝴蝶刀刀
TA貢獻1801條經驗 獲得超8個贊
Distinct()
IEqualityComparerEqualsGetHashCodeAuthor
public class AuthorEquals : IEqualityComparer<Author>{
public bool Equals(Author left, Author right)
{
if((object)left == null && (object)right == null)
{
return true;
}
if((object)left == null || (object)right == null)
{
return false;
}
return left.FirstName == right.FirstName && left.LastName == right.LastName;
}
public int GetHashCode(Author author)
{
return (author.FirstName + author.LastName).GetHashCode();
}}
吃雞游戲
TA貢獻1829條經驗 獲得超7個贊
IEquatable, EqualsGetHashCodeGroupBy
var temp = books.SelectMany(book => book.Authors)
.GroupBy (y => y.FirstName + y.LastName )
.Select (y => y.First ());foreach (var author in temp){
Console.WriteLine(author.FirstName + " " + author.LastName);}- 3 回答
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