Use the simplest example to understand the strategy Pattern)

When an action has multiple implementation methods, you need to select a method to execute the action based on the actual situation, you can consider using the Policy mode.

 

Abstract actions into interfaces, such as playing balls into interfaces.

    public interface IBall
    {
        void Play();
    }

 

It may be playing football, basketball, volleyball, etc. These balls are abstracted into classes that implement interfaces.

    public class Football : IBall
    {
        public void Play()
        {
Console. writeline ("I like football ");
        }
    }
    public class Basketball : IBall
    {
        public void Play()
        {
Console. writeline ("I like basketball ");
        }
    }
    public class Volleyball : IBall
    {
        public void Play()
        {
Console. writeline ("I like volleyball ");
        }
    }   

 

Another class is specifically used to select the ball and execute the interface method.

    public class SportsMan
    {
        private IBall ball;
        public void SetHobby(IBall myBall)
        {
            ball = myBall;
        }
        public void StartPlay()
        {
            ball.Play();
        }
    }

 

The client needs the user to make a choice and instantiate a specific class according to different options.

    class Program
    {
        static void Main(string[] args)
        {
            IBall ball = null;
            SportsMan man = new SportsMan();
            while (true)
            {
Console. writeline ("select your favorite ball games (1 = football, 2 = Basketball, 3 = volleyball )");
                string input = Console.ReadLine();
                switch (input)
                {
                    case "1":
                        ball = new Football();
                        break;
                    case "2":
                        ball = new Basketball();
                        break;
                    case "3":
                        ball = new Volleyball();
                        break;
                }
                man.SetHobby(ball);
                man.StartPlay();
            }
        }
    }

Use the simplest example to understand the strategy Pattern)