使具体返回类型通用
本文关键字:返回类型 | 更新日期: 2023-09-27 18:20:58
考虑以下两种方法,它们本质上是彼此的复制和粘贴版本
public static List<Book> GetSubSet(List<Book> incomingList)
{
List<Book> returnList = new List<Book>();
Random r = new Random();
Console.WriteLine("Enter size of random subset: ");
int randomInt = 0;
int size = Convert.ToInt32(Console.ReadLine());
while (size > incomingList.Count)
{
Console.WriteLine("Size too large, enter smaller subset: ");
size = Convert.ToInt32(Console.ReadLine());
}
while (returnList.Count < size)
{
randomInt = r.Next(incomingList.Count);
if (!returnList.Contains(incomingList[randomInt]))
{
returnList.Add(incomingList[randomInt]);
}
}
return returnList;
}
public static List<Pet> GetSubSet(List<Pet> incomingList)
{
Random r = new Random();
List<Pet> returnList = new List<Pet>();
Console.WriteLine("Enter random subset size: ");
int size = Convert.ToInt32(Console.ReadLine());
while (size > incomingList.Count)
{
Console.WriteLine("Size too large. Enter random subset size: ");
size = Convert.ToInt32(Console.ReadLine());
}
while (returnList.Count < size)
{
int randomInt = r.Next(incomingList.Count);
if (!returnList.Contains(incomingList[randomInt]))
{
returnList.Add(incomingList[randomInt]);
}
}
return returnList;
}
显然,这不是很OO,我希望有一个可以处理任何类型的方法。我不想使用继承,因为书和狗之间没有逻辑连接,也不想包含类型,因为包含也没有意义。所以我们只剩下一个接口。类似的东西
interface ISubset
{
IEnumerable<T> GetSubset();
}
我见过,但我不知道如何使尖括号接受任何泛型类型。如何使IEnumerable类型成为泛型,以便在任何类上实现GetSubset方法?
使其通用:
public static List<T> GetSubSet<T>(List<T> incomingList)
{
Random r = new Random();
List<T> returnList = new List<T>();
Console.WriteLine("Enter random subset size: ");
int size = Convert.ToInt32(Console.ReadLine());
while (size > incomingList.Count)
{
Console.WriteLine("Size too large. Enter random subset size: ");
size = Convert.ToInt32(Console.ReadLine());
}
while (returnList.Count < size)
{
int randomInt = r.Next(incomingList.Count);
if (!returnList.Contains(incomingList[randomInt]))
{
returnList.Add(incomingList[randomInt]);
}
}
return returnList;
}
您可以使GetSubSet
方法通用:
public static List<T> GetSubSet<T>(List<T> incomingList)
{
var returnList = new List<T>();
Random r = new Random();
Console.WriteLine("Enter size of random subset: ");
int randomInt = 0;
int size = Convert.ToInt32(Console.ReadLine());
while (size > incomingList.Count)
{
Console.WriteLine("Size too large, enter smaller subset: ");
size = Convert.ToInt32(Console.ReadLine());
}
while (returnList.Count < size)
{
randomInt = r.Next(incomingList.Count);
if (!returnList.Contains(incomingList[randomInt]))
{
returnList.Add(incomingList[randomInt]);
}
}
return returnList;
}
然后你可以这样使用它:
List<Pet> incomingList = ...
List<Pet> result = GetSubSet(incomingList);
注意,我们在调用GetSubSet
方法时没有指定类型,这是可能的,这要归功于编译器对方法的泛型类型推断。这相当于:
List<Pet> result = GetSubSet<Pet>(incomingList);
但是编译器能够推断出这一点。
有一个方法,并使该方法本身具有泛型。
public static List<T> GetSubSet<T>(List<T> incomingList)