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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. /* Name of the class has to be "Main" only if the class is public. */
  8. class Visitors
  9. {
  10. 	public static void main (String[] args) throws java.lang.Exception
  11. 	{
  12.         List<K> handlers = Arrays.asList(new K1(), new K2(), new K3());
  13.         S sample = new A();
  14.         for (K visitor : handlers) {
  15.             sample.visit(visitor);
  16.         }
  17.         sample = new B();
  18.         for (K visitor : handlers) {
  19.             sample.visit(visitor);
  20.         }
  21. 	}
  22. }
  23.  
  24. interface K {
  25.     void handle(A a);
  26.     void handle(B b);
  27. }
  28. class A implements S {
  29.     public void visit(K visitor) { visitor.handle(this); }
  30. }
  31. class B implements S {
  32.     public void visit(K visitor) { visitor.handle(this); }
  33. }
  34.  
  35. interface S {
  36.     void visit(K visitor);
  37. }
  38. class K1 implements K {
  39.     public void handle(A a) { System.out.println("K1 handling A"); }
  40.     public void handle(B b) { System.out.println("K1 handling B"); }
  41. }
  42. class K2 implements K {
  43.     public void handle(A a) { System.out.println("K2 handling A"); }
  44.     public void handle(B b) { System.out.println("K2 handling B"); }
  45. }
  46. class K3 implements K {
  47.     public void handle(A a) { System.out.println("K3 handling A"); }
  48.     public void handle(B b) { System.out.println("K3 handling B"); }
  49. }
Success #stdin #stdout 0.06s 32576KB
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K1 handling A
K2 handling A
K3 handling A
K1 handling B
K2 handling B
K3 handling B
https://ideone.com/fV7Moh
language:
Java (HotSpot 12)
created:
5 years ago
visibility:
public

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