//简易的泛型方法
//泛型使程序员能够为类型定义和方法参数定义“占位符”(正式名称为类型参数)，类型参数等到创建泛型类型活调用泛型方法时再指定
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace SimpleGeneric
{
//创建泛型方法
public class MyHelperClass
{
public static void Swap<T>(ref T a, ref T b)
{
Console.WriteLine("you sent the swap() method a {0}", typeof(T));
T temp;
temp = a;
a = b;
b = temp;
}
public static void DisplayBaseClass<T>()
{
Console.WriteLine("Base class of {0} is :{1}", typeof(T), typeof(T).BaseType);
}
}
//创建泛型结构
public struct Point<T>
{
//泛型状态数据
private T xPos;
private T yPos;
//泛型构造函数
public Point(T xVal,T yVal)
{
xPos = xVal;
yPos = yVal;
}
//泛型属性
public T X
{
get { return xPos; }
set { xPos = value; }
}
public T Y
{
get { return yPos; }
set { yPos = value; }
}
public override string ToString()
{
return string.Format("[{0},{1}]", xPos, yPos);
}
//重置字段为类型参数的默认值
public void ResetPoint()
{
//default和泛型一起用时，它表示一个类型参数的默认值
xPos = default(T);
yPos = default(T);
}
}
class Program
{
static void Main(string[] args)
{
int a = 5;
int b = 6;
string str1 = "apple";
string str2 = "orange";
Console.WriteLine("Before swap:\n a={0} b={1}", a, b);
//当泛型方法需要参数时，我们可以选择省略类型参数
//MyHelperClass.Swap<int>(ref a, ref b);
MyHelperClass.Swap(ref a, ref b);
Console.WriteLine("After swap:\n a={0} b={1}", a, b);
//如果方法不带任何参数，必须提供类型参数
MyHelperClass.DisplayBaseClass<int>();
Console.WriteLine();
Console.WriteLine("Before swap:\n str1={0} str2={1}", str1, str2);
//当泛型方法需要参数时，我们可以选择省略类型参数
//MyHelperClass.Swap<string>(ref str1, ref str2);
MyHelperClass.Swap(ref str1, ref str2);
Console.WriteLine("After swap:\n str1={0} str2={1}", str1, str2);
//如果方法不带任何参数，必须提供类型参数
MyHelperClass.DisplayBaseClass<string>();
Console.WriteLine();
//使用int的point
Point<int> p = new Point<int>(10, 10);
Console.WriteLine("p.ToString()={0}",p.ToString());
p.ResetPoint();
Console.WriteLine("p.ToString()={0}", p.ToString());
Console.WriteLine();
//使用double的Point
Point<double> p2 = new Point<double>(5.4, 3.3);
Console.WriteLine("p.ToString()={0}", p2.ToString());
p2.ResetPoint();
Console.WriteLine("p.ToString()={0}", p2.ToString());
Console.WriteLine();
//交换两个Points
Point<int> pointA = new Point<int>(20, 10);
Point<int> pointB = new Point<int>(34, 1);
Console.WriteLine("Before swap:\n {0} {1}", pointA, pointB);
//当泛型方法需要参数时，我们可以选择省略类型参数
//MyHelperClass.Swap<Point<int>>(ref pointA, ref pointB);
MyHelperClass.Swap(ref pointA, ref pointB);
Console.WriteLine("After swap:\n {0} {1}", pointA, pointB);
Console.ReadLine();
}
}
}
