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  1. interface Collection<T> {
  2. 	void add(T t);
  3. 	void addRange(T[] ts);
  4. }
  5.  
  6. class CollectionBase<T> implements Collection<T> {
  7. 	@Override 
  8. 	public void add(T t) {
  9.  
  10. 	}
  11. 	@Override
  12. 	public void addRange(T[] ts) {
  13. 		for (T t : ts) {
  14. 			add(t);
  15. 		}
  16. 	}
  17. }
  18.  
  19. class CollectionWithCounter<T> implements Collection<T> {
  20. 	int elementsCount = 0;
  21. 	Collection base;
  22.  
  23. 	public CollectionWithCounter(Collection<T> b) {
  24. 		base = b;
  25. 	}
  26. 	@Override
  27. 	public void add(T t) {
  28. 		elementsCount++;
  29. 		base.add(t);
  30. 	}
  31.  
  32. 	@Override
  33. 	public void addRange(T[] ts) {
  34. 		elementsCount += ts.length;
  35. 		base.addRange(ts);
  36. 	}
  37. }
  38.  
  39. class Main {
  40. 	public static void main(String[] args) {
  41. 		CollectionWithCounter<Object> cc;
  42.  
  43. 		cc = new CollectionWithCounter<>(new CollectionBase());
  44. 		cc.add(null);
  45. 		cc.add(null);
  46. 		cc.add(null);
  47. 		System.out.println("elementsCount = " + cc.elementsCount);
  48.  
  49. 		cc = new CollectionWithCounter<>(new CollectionBase());
  50. 		cc.addRange(new Object[3]);
  51. 		System.out.println("elementsCount = " + cc.elementsCount);
  52. 	}
  53. }
Success #stdin #stdout 0.03s 711168KB
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elementsCount = 3
elementsCount = 3
https://ideone.com/JY4mGz
language:
Java (HotSpot 12)
created:
8 years ago
visibility:
public

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