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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7.  
  8. class Parent {
  9.     // those should be declared outside
  10.     static interface Foo {
  11.         void foo();
  12.     }
  13.     static interface Bar {
  14.         void bar();
  15.     }
  16.  
  17.     protected String neededByFoo = "foo";
  18.     protected String neededByBar = "bar";
  19.  
  20.     class FooA implements Foo {
  21.         public void foo() {
  22.             System.out.println(neededByFoo + "A");
  23.         }
  24.     }
  25.     class FooB implements Foo {
  26.         public void foo() {
  27.             System.out.println(neededByFoo + "B");
  28.         }
  29.     }
  30.     class BarA implements Bar {
  31.         public void bar() {
  32.             System.out.println(neededByBar + "A");
  33.         }
  34.     }
  35.     class BarB implements Bar {
  36.         public void bar() {
  37.             System.out.println(neededByBar + "B");
  38.         }
  39.     }
  40.     public static interface FooBar extends Foo, Bar {}
  41.     private static class FooBarDelegate implements FooBar {
  42.         Foo fooDelegate;
  43.         Bar barDelegate;
  44.         private FooBarDelegate(Foo f, Bar b) { fooDelegate = f; barDelegate = b; }
  45.         public void foo() { fooDelegate.foo(); }
  46.         public void bar() { barDelegate.bar(); }
  47.     }
  48.  
  49.     public FooBar fooAbarA() {
  50.         return new FooBarDelegate(new FooA(), new BarA());
  51.     }
  52.     public FooBar fooBbarA() {
  53.         return new FooBarDelegate(new FooB(), new BarA());
  54.     }
  55.     public FooBar fooAbarB() {
  56.         return new FooBarDelegate(new FooA(), new BarB());
  57.     }
  58.     public FooBar fooBbarB() {
  59.         return new FooBarDelegate(new FooB(), new BarB());
  60.     }
  61.  
  62.     public static void main(String[] args) {
  63.     	Parent p = new Parent();
  64.     	foobar(p.fooAbarA());
  65.     	foobar(p.fooAbarB());
  66.     	foobar(p.fooBbarA());
  67.     	foobar(p.fooBbarB());
  68.     }
  69.     private static void foobar(FooBar fb) {
  70.     	fb.foo();
  71.     	fb.bar();
  72.     }
  73. }
Success #stdin #stdout 0.1s 28084KB
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Standard input is empty
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fooA
barA
fooA
barB
fooB
barA
fooB
barB
https://ideone.com/Hj4D65
language:
Java (HotSpot 12)
created:
6 years ago
visibility:
public

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