如何按字段对列表进行排序

Good day 4 u all

美好的一天4你们

I have a list of objects

我有一个对象列表

My objects like

我的对象喜欢

Product = "iPhone"; 
Category = "SmartPhone";

Product = "HP"; 
Category = "PC";

Product = "HTC"; 
Category = "SmartPhone";

And I insert each object into my test so its like

我将每个对象插入到我的测试中，就像它一样

List<Myobject> MyList = new List<Myobject>();

And now I need to sord/order MyList by the category

现在我需要根据类别对MyList进行sord / order

As I need my list to show the SmartPhone category first then other

因为我需要我的列表首先显示SmartPhone类别然后是其他类别

3 个解决方案

#1

You can use List.Sort

您可以使用List.Sort

l.Sort((p, q) => p.Category.CompareTo(q.Category));

The advantage over the LINQ OrderBy is that you'll order the list in-place instead of generating an IOrderedEnumerable<T> that then you have to re-transform in a List<T>.

LINQ OrderBy的优势在于您可以就地排序列表，而不是生成IOrderedEnumerable ，然后您必须在List 中重新转换。

#2

Check out the LINQ OrderBy extension method.

查看LINQ OrderBy扩展方法。

MyList.OrderBy (p => p.Category);

If you need a more complex way to sort the categories, you could create a class which implements the IComparer interface, and implement your sort logic in it.

如果需要更复杂的方法对类别进行排序，可以创建一个实现IComparer接口的类，并在其中实现排序逻辑。

        public class SmartphonesFirst : IComparer<Product>
        {
            const string Smartphone = "Smartphone";

            public int Compare( Product x, Product y )
            {
                if( x.Category == Smartphone && y.Category != Smartphone )
                {
                    return -1;
                }
                if( y.Category == Smartphone && x.Category != Smartphone )
                {
                    return 1;
                }
                else
                {
                    return Comparer<String>.Default.Compare (x.Category, y.Category);
                }
            }
        }

You can do it without using LINQ:

你可以不使用LINQ来做到这一点：

            var l = new List<Product> ();
            l.Add (new Product ()
            {
                Name = "Omnia 7",
                Category = "Smartphone"
            });

            l.Add (new Product ()
            {
                Name = "Mercedes",
                Category = "Car"
            });

            l.Add (new Product ()
            {
                Name = "HTC",
                Category = "Smartphone"
            });

            l.Add (new Product ()
            {
                Name = "AMD",
                Category = "CPU"
            });

            l.Sort (new SmartphonesFirst ());

            foreach( var p in l )
            {
                Console.WriteLine (String.Format ("{0} : {1}", p.Category, p.Name));
            }

Or, with using LINQ:

或者，使用LINQ：

            var l = new List<Product> ();
            l.Add (new Product ()
            {
                Name = "Omnia 7",
                Category = "Smartphone"
            });

            l.Add (new Product ()
            {
                Name = "Mercedes",
                Category = "Car"
            });

            l.Add (new Product ()
            {
                Name = "HTC",
                Category = "Smartphone"
            });

            l.Add (new Product ()
            {
                Name = "AMD",
                Category = "CPU"
            });

            var sorted = l.OrderBy (p => p, new SmartphonesFirst ());

            foreach ( var p in sorted )
            {
                Console.WriteLine (String.Format ("{0} : {1}", p.Category, p.Name));
            }

#3

You can use the Sort method and a custom comparison, to sort by category (descending) and then by product (ascending):

您可以使用Sort方法和自定义比较，按类别（降序）排序，然后按产品（升序）排序：

MyList.Sort((a, b) => {
  // compare b to a to get descending order
  int result = b.Category.CompareTo(a.Category);
  if (result == 0) {
    // if categories are the same, sort by product
    result = a.Product.CompareTo(b.Product);
  }
  return result;
});

If you want to single out smartphones, and then sort ascending:

如果你想挑出智能手机，然后按升序排序：

MyList.Sort((a, b) => {
  int result = (a.Category == "SmartPhone" ? 0 : 1) - (b.Category == "SmartPhone" ? 0 : 1);
  if (result == 0) {
    result = a.Category.CompareTo(b.Category);
    if (result == 0) {
      result = a.Product.CompareTo(b.Product);
    }
  }
  return result;
});

#1