fork download
copy 
  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.*;
  4. import java.lang.*;
  5. import java.io.*;
  6.  
  7. class Ref<T> {
  8. 	private T item = null;
  9. 	public Ref() {}
  10. 	public Ref(T item) { this.item = item; }
  11. 	public T get() { return item; }
  12. 	public void set(T newValue) { item = newValue; }
  13. }
  14.  
  15. class RefPair<A, B> {
  16. 	private final Ref<A> aRef;
  17. 	private final Ref<B> bRef;
  18.  
  19. 	public RefPair() {
  20. 		this(new Ref<A>(), new Ref<B>());
  21. 	}
  22.  
  23. 	private RefPair(Ref<A> aRef, Ref<B> bRef) {
  24. 		this.aRef = aRef;
  25. 		this.bRef = bRef;
  26. 	}
  27.  
  28. 	public RefPair<B, A> inverted() { return new RefPair<>(bRef, aRef); }
  29.  
  30. 	public A 	getFirst() 		  { return aRef.get(); }
  31. 	public void setFirst(A newA)  { aRef.set(newA); }
  32. 	public B	getSecond() 	  { return bRef.get(); }
  33. 	public void setSecond(B newB) { bRef.set(newB); }
  34. }
  35.  
  36. enum Flipper {
  37. 	A(makePair()),
  38. 	B(makePair()),
  39. 	Y(B.pair.inverted()),
  40. 	Z(A.pair.inverted());
  41.  
  42. 	private final RefPair<Flipper, Flipper> pair;
  43.  
  44. 	private Flipper(RefPair<Flipper, Flipper> pair) {
  45. 		this.pair = pair;
  46. 		pair.setFirst(this);
  47. 	}
  48.  
  49. 	public Flipper flip() { return pair.getSecond(); }
  50.  
  51. 	private static RefPair<Flipper, Flipper> makePair() {
  52. 		return new RefPair();
  53. 	}
  54. }
  55.  
  56. /* Name of the class has to be "Main" only if the class is public. */
  57. class Ideone
  58. {
  59. 	public static void main (String[] args) throws java.lang.Exception
  60. 	{
  61. 		System.out.println(Flipper.A);
  62. 		System.out.println(Flipper.A.flip());
  63. 		System.out.println(Flipper.Z);
  64. 		System.out.println(Flipper.Z.flip());
  65. 	}
  66. }
Success #stdin #stdout 0.1s 320576KB
comments (?)
stdin
copy 
Standard input is empty
stdout
copy 
A
Z
Z
A
https://ideone.com/8HlAZL
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

Share or Embed source code

Discover > Sphere Engine API

The brand new service which powers Ideone!

Discover > IDE Widget

Widget for compiling and running the source code in a web browser!