瞭解如何使用單例模式？

Question

我一直在試圖編碼這樣的東西：

1類創建一個類2（類t =新類（））的實例。這個實例可以在1,2和3類中使用。 我一直在找東西，找到了「Singleton Pattern」。我不明白，我怎麼落實到我的代碼，這雖然和來源公正的幾個都在說不同的東西......

感謝您的幫助，非常感謝:)

Answer 1

辛格爾頓例子：如果你有一個班級電話簿，並且你想讓你的程序的每一個班級都指向同一個電話簿。您將使Class Phonebook成爲Singleton-Class。

換句話說：使用Singleton模式來確定每一個其他代碼是指單一類的同一個對象。

class Phonebook { 
    //Make the constructor private so no one can create objects, but this class 
    private Phonebook() { 
    } 
    // to static members to hold (m_Instance) and get (getInstacnce) the Singleton Instance of the class 
    private static Phonebook m_Instance; 
    public static Phonebook getInstance() { 
     if (m_Instance == null) { 
      // first call to getInstance, creates the Singelton Instance, only we (Phonebook) can call the constructor; 
      m_Instance = new Phonebook(); 
     } 
     return m_Instance; //always the same Instance of Phonebook 
    } 
    ... // Members of the Phonebook (add/getPhoneNumber) 
} 

軟件的每個部分都會得到相同的電話本實例。所以我們可以註冊phonenumbers，每隔一個班級都可以閱讀。

... 
Phonebook l_Phonebook = Phonebook.getInstance(); 
l_Phonebook.addPhoneNumber("Yoschi", "01774448882") 
... 
// somewhere else 
Phonebook l_Phonebook = Phonebook.getInstance(); 
Phone.getInstance().call(l_Phonebook.getPhoneNumber("Yoschi")); 

Answer 2

下面是描述的鏈接：

http://en.wikipedia.org/wiki/Singleton_pattern

樣品代碼將是

public class singleton 
    { 
     public static singleton _obj; 
     private singleton() 
     { 
      // prevents instantiation from external entities 
     } 
     public static singleton GetObject() // instead of creating new operator, declare a method and that will create object and return it. 
     { 
      if (_obj == null) //Checking if the instance is null, then it will create new one and return it 
      //otherwise it will return previous one. 
      { 
       _obj = new singleton(); 
      } 
      return _obj; 
     } 
     public void printing(string s) 
     { 
      Console.WriteLine(s); 
     } 
    } 

這是一個C＃代碼但其概念是一樣的java。