java的外單獨的類訪問匿名類

Question

假設我有以下類

Class0

public abstract class Class0 { 

public Class0(){} 
    public void abmethod1(){ 
     System.out.println("Abstract method 1"); 
    } 

    public void abmethod2(){ 
     System.out.println("Abstract method 2"); 
    } 
} 

的Class1

public class Class1 { 
    private List<Integer> aList; 

    public Class1(){ 
     this.aList= new ArrayList<>(); 
    } 

    public Integer getElementAt(int i){ 
     return this.aList.get(i); 
    } 

    public int getSize(){ 
     return this.aList.size(); 
    } 

    public void add(int num){ 
     this.aList.add(num); 
    } 
} 

的Class2

public class Class2 { 
    private Class0 c0; 
    private Class3 c3; 
    public Class2(){ 
     this.c0 = new Class0() { 
      Class1 c1 = new Class1(); 

      @Override 
      public void abmethod1(){ 
       System.out.println("Abstract method 1 called. Size is " + c1.getSize()); 
      } 

      @Override 
      public void abmethod2(){ 
       c1.add(1); 
       c1.add(2); 
       c1.add(3); 
       System.out.println("Abstract method 2 called. Size is " + c1.getSize()); 
      } 
     }; 
     this.c3 = new Class3(); 
     c3.methodc2(c0); 
    } 
} 

Class3的

public class Class3{ 
    public void methodc2(Class0 c0){ 
     c0.abmethod1(); 
     c0.abmethod2(); 
    } 
} 

CLASS4

public class Class4 { 
    private Class2 c2; 

    public Class4(){ 
     c2 = new Class2(); 
    } 
} 

Class5

public class Class5 { 
    private Class2 c2; 

    public void method2(){ 
     this.c2 = new Class2(); 
    } 
} 

然後我るn個主類

public class Class6 { 
    public static void main(String[] afg){ 
     Class4 c4 = new Class4(); 
     Class5 c5 = new Class5(); 
     c5.method2(); 
    } 
} 

而我得到的消息

Abstract method 1 called. Size is 0 
Abstract method 2 called. Size is 3 
Abstract method 1 called. Size is 0 
Abstract method 2 called. Size is 3 

所以我想利用我的列表的最後大小（在此爲3）每次我打電話內Class3的匿名上課時間。我怎樣才能防止它產生Class0的新實例，以便採取輸出

Abstract method 1 called. Size is 0 
Abstract method 2 called. Size is 3 
Abstract method 1 called. Size is 3 
Abstract method 2 called. Size is 6 

預先感謝您

Answer 1

如果你的目標是，Class2所有實例將共享Class0同一實例，您可以通過使成員Class2成爲靜態來實現。在這種情況下，您需要在靜態初始化塊中初始化c0變量，而不是在構造函數中。

public class Class2 { 
    private static Class0 c0; 
    private Class3 c3; 
    static 
    { 
     Class2.c0 = new Class0() { 
      Class1 c1 = new Class1(); 

      @Override 
      public void abmethod1(){ 
       System.out.println("Abstract method 1 called. Size is " + c1.getSize()); 
      } 

      @Override 
      public void abmethod2(){ 
       c1.add(1); 
       c1.add(2); 
       c1.add(3); 
       System.out.println("Abstract method 2 called. Size is " + c1.getSize()); 
      } 
     }; 
    } 
    public Class2(){ 
     this.c3 = new Class3(); 
     c3.methodc2(c0); 
    } 
} 

如果不知道代碼的用途，是否所有這些都是有道理的。