表示定义一组条件并确定指定对象是否符合这些条件的方法
public delegate bool Predicate( T obj) 此委托由 Array 和 List<(Of <(T>)>) 类的几种方法使用，用于在集合中搜索元素。
用户不需要显式创建委托，也不需要指定泛型方法的类型参数。 编译器会根据您提供的方法参数确定必需的类型。
View Code 1 using System; 2 using System.Drawing; 3 4 public class Example 5 { 6 public static void Main() 7 { 8 // Create an array of five Point structures. 9 Point[] points = { new Point(100, 200), 10 new Point(150, 250), new Point(250, 375), 11 new Point(275, 395), new Point(295, 450) };12 13 // To find the first Point structure for which X times Y 14 // is greater than 100000, pass the array and a delegate15 // that represents the ProductGT10 method to the static 16 // Find method of the Array class. 17 Point first = Array.Find(points, ProductGT10);18 19 // Note that you do not need to create the delegate 20 // explicitly, or to specify the type parameter of the 21 // generic method, because the C# compiler has enough22 // context to determine that information for you.23 24 // Display the first structure found.25 Console.WriteLine("Found: X = {0}, Y = {1}", first.X, first.Y);26 }27 28 // This method implements the test condition for the Find29 // method.30 private static bool ProductGT10(Point p)31 {32 if (p.X * p.Y > 100000)33 {34 return true;35 }36 else37 {38 return false;39 }40 }41 }42 43 /* This code example produces the following output:44 45 Found: X = 275, Y = 39546 */