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  1. interface A {
  2.   void doSomethingA1();
  3.   void doSomethingA2();
  4.   void doSomethingA3();
  5.  
  6.   interface Delegate extends A {
  7.     default void doSomethingA1() { getDelegate(this).doSomethingA1(); }
  8.     default void doSomethingA2() { getDelegate(this).doSomethingA2(); }  
  9.     default void doSomethingA3() { getDelegate(this).doSomethingA3(); }  
  10.     A getDelegate(A _x);
  11.   }
  12. }
  13.  
  14.  
  15. interface B extends A {
  16.   void doSomethingB(); 
  17.  
  18.   interface Delegate extends B, A.Delegate {
  19.     B getDelegate(B _x);    
  20.     default A getDelegate(A _x) { return getDelegate(this); }
  21.     default void doSomethingB() { getDelegate(this).doSomethingB(); }
  22.   }
  23. }
  24.  
  25.  
  26. interface C extends A {
  27.   void doSomethingC(); 
  28.  
  29.   interface Delegate extends C, A.Delegate {
  30.     C getDelegate(C _x);    
  31.     default A getDelegate(A _x) { return getDelegate(this); }
  32.     default void doSomethingC() { getDelegate(this).doSomethingC(); }
  33.   }
  34. }
  35.  
  36.  
  37. interface X extends A, B, C {
  38.   void doSomethingX(); 
  39. }
  40.  
  41.  
  42. class AImpl implements A { 
  43.   int x; 
  44.   public void doSomethingA1() { /* ... */ }
  45.   public void doSomethingA2() { /* ... */ }  
  46.   public void doSomethingA3() { /* ... */ }
  47. }
  48.  
  49.  
  50. class BImpl implements B, A.Delegate {
  51.   A a;
  52.   public A getDelegate(A _x) { return a; }
  53.   public void doSomethingB() { /* ... */ }
  54. }
  55.  
  56.  
  57. class CImpl implements C, A.Delegate {
  58.   A a;
  59.   public A getDelegate(A _x) { return a; }
  60.   public void doSomethingC() { /* ... */ }  
  61. }
  62.  
  63. class XImpl implements X, B.Delegate, C.Delegate {
  64.   B b;
  65.   C c;
  66.  
  67.   public B getDelegate(B _x) { return b; }
  68.   public C getDelegate(C _x) { return c; }
  69.  
  70.   // приходится явно разрешить diamong problem
  71.   // иначе error: class XImpl inherits unrelated defaults for getDelegate(A) from types B.Delegate and C.Delegate
  72.   public A getDelegate(A _x) { return b; }  
  73.  
  74.   public void doSomethingX() { /* ... */ }  
  75. }
  76.  
  77.  
  78. class Main {
  79.   public static void main(String[] args) { }
  80.  
  81.   void doIt() {
  82.   	X x = null;  // createX(...)
  83.   	x.doSomethingX();
  84.   	x.doSomethingA1();
  85.   	x.doSomethingA2();
  86.   	x.doSomethingA3();
  87.   	x.doSomethingB();
  88.   	x.doSomethingC();  	
  89.   }
  90. }
  91.  
Success #stdin #stdout 0.04s 4575232KB
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https://ideone.com/wCWgoX
language:
Java (HotSpot 12)
created:
6 years ago
visibility:
public

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