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  1. /* package whatever; // don't place package name! */
  2.  
  3. import java.util.ArrayList;
  4. import java.util.Arrays;
  5. import java.util.Iterator;
  6. import java.util.List;
  7. import java.util.Objects;
  8. import java.util.Spliterator;
  9. import java.util.Spliterators;
  10. import java.util.function.BiFunction;
  11. import java.util.stream.Collectors;
  12. import java.util.stream.Stream;
  13. import java.util.stream.StreamSupport;
  14.  
  15.  
  16.  
  17. /* Name of the class has to be "Main" only if the class is public. */
  18. class Ideone
  19. {
  20. 	public static void main(String[] args) {
  21. 		List<List<String>> list1 = Arrays.asList(Arrays.asList("ABC", "123", "456"), Arrays.asList("DEF", "234", "567"),
  22. 				Arrays.asList("GHI", "345", "678"));
  23. 		List<List<String>> list2 = Arrays.asList(Arrays.asList("ABC", "789", "012"), Arrays.asList("DEF", "890", "123"),
  24. 				Arrays.asList("GHI", "901", "234"));
  25.  
  26. 		List<List<String>> a = zip(list1.stream(), list2.stream(), (l1, l2) -> {
  27. 			List<String> l = new ArrayList<>(l1);
  28. 			l.addAll(l2.subList(1, l2.size()));
  29. 			return l;
  30. 		}).collect(Collectors.toList());
  31.  
  32. 		System.out.println(a);
  33. 	}
  34.  
  35. 		public static <A, B, C> Stream<C> zip(Stream<? extends A> a, Stream<? extends B> b,
  36. 			BiFunction<? super A, ? super B, ? extends C> zipper) {
  37. 		Objects.requireNonNull(zipper);
  38. 		@SuppressWarnings("unchecked")
  39. 		Spliterator<A> aSpliterator = (Spliterator<A>) Objects.requireNonNull(a).spliterator();
  40. 		@SuppressWarnings("unchecked")
  41. 		Spliterator<B> bSpliterator = (Spliterator<B>) Objects.requireNonNull(b).spliterator();
  42.  
  43. 		// Zipping looses DISTINCT and SORTED characteristics
  44. 		int both = aSpliterator.characteristics() & bSpliterator.characteristics()
  45. 				& ~(Spliterator.DISTINCT | Spliterator.SORTED);
  46. 		int characteristics = both;
  47.  
  48. 		long zipSize = ((characteristics & Spliterator.SIZED) != 0)
  49. 				? Math.min(aSpliterator.getExactSizeIfKnown(), bSpliterator.getExactSizeIfKnown()) : -1;
  50.  
  51. 		Iterator<A> aIterator = Spliterators.iterator(aSpliterator);
  52. 		Iterator<B> bIterator = Spliterators.iterator(bSpliterator);
  53. 		Iterator<C> cIterator = new Iterator<C>() {
  54. 			@Override
  55. 			public boolean hasNext() {
  56. 				return aIterator.hasNext() && bIterator.hasNext();
  57. 			}
  58.  
  59. 			@Override
  60. 			public C next() {
  61. 				return zipper.apply(aIterator.next(), bIterator.next());
  62. 			}
  63. 		};
  64.  
  65. 		Spliterator<C> split = Spliterators.spliterator(cIterator, zipSize, characteristics);
  66. 		return (a.isParallel() || b.isParallel()) ? StreamSupport.stream(split, true)
  67. 				: StreamSupport.stream(split, false);
  68. 	}
  69.  
  70.  
  71. }
Success #stdin #stdout 0.2s 320832KB
comments (?)
stdin 
Standard input is empty
stdout 
[[ABC, 123, 456, 789, 012], [DEF, 234, 567, 890, 123], [GHI, 345, 678, 901, 234]]
https://ideone.com/eqLKd6
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
public

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