C#經典機試題(貓叫)

　　貓大叫一聲，所有的老鼠都開始逃跑，主人被驚醒。(C#語言)

　　1.要有聯動性，老鼠和主人的行為是被動的。

　　2.考慮可擴充性，貓的叫聲可能引起其他聯動效應。

1、運用介面：

代碼

public interface Observer { 
void Response(); //觀察者的響應，這是老鼠見到貓的反映
}

public interface Subject { 
void AimAt(Observer obs); //針對哪些觀察者，這裡指貓的要撲捉的對象---老鼠 
}
/// <summary>
/// 老鼠的相應，繼承被觀察的對象
/// </summary>
public class Mouse : Observer { 

private string name;
public Mouse(string name, Subject subj) { 
this.name = name; 
        subj.AimAt(this);
    }
public void Response() { 
        Console.WriteLine(name + " attempt to escape!"); 
    } 

}
/// <summary>
/// 主人的相應，繼承被觀察的對象
/// </summary>
public class Master : Observer { 
public Master(Subject subj) {
        subj.AimAt(this); 
    }
public void Response() { 
        Console.WriteLine("Host waken!"); 
    } 
}
/// <summary>
/// 貓觀充當觀察者的角色
/// </summary>
public class Cat : Subject { 
private ArrayList observers; 
public Cat() { 
this.observers = new ArrayList(); 
    } 
public void AimAt(Observer obs) { 
this.observers.Add(obs); 
    } 
public void Cry() { 
        Console.WriteLine("Cat cryed!"); 
foreach (Observer obs in this.observers) { 
            obs.Response(); 
        }
    }
}

class MainClass { 
static void Main(string[] args) { 
        Cat cat = new Cat(); 
        Mouse mouse1 = new Mouse("mouse1", cat); 
        Mouse mouse2 = new Mouse("mouse2", cat); 
        Master master = new Master(cat);
        cat.Cry();
    }
}

 

2、 使用event -- delegate設計..

代碼

public delegate void SubEventHandler(); 

public abstract class Subject { 
public event SubEventHandler SubEvent; 
protected void FireAway() { 
if (this.SubEvent != null) 
this.SubEvent(); 
    }  
} 
public class Cat : Subject {  
public void Cry() { 
        Console.WriteLine("cat cryed."); 
this.FireAway();
    }
} 
public abstract class Observer {
public Observer(Subject sub) { 
        sub.SubEvent += new SubEventHandler(Response); 
    } 
public abstract void Response();  
} 
public class Mouse : Observer { 
private string name; 
public Mouse(string name, Subject sub) : base(sub) {  
this.name = name;
    } 
public override void Response() {
        Console.WriteLine(name + " attempt to escape!"); 
    } 
}
public class Master : Observer { 
public Master(Subject sub) : base(sub){
    } 
public override void Response() { 
        Console.WriteLine("host waken"); 
    } 
} 
class Class1 { 
static void Main(string[] args) { 
        Cat cat = new Cat();
        Mouse mouse1 = new Mouse("mouse1", cat); 
        Mouse mouse2 = new Mouse("mouse2", cat); 
        Master master = new Master(cat); cat.Cry(); 
    } 
}

 轉自：http://kb.cnblogs.com/page/50471/