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  1. import java.util.Random;
  2. import java.util.Arrays;
  3.  
  4. public class Main {
  5. 	private static Random rng = new Random();
  6. 	private static String[] ourStrings = {
  7. 		"1.one", "2.two", "3.three"
  8. 	};
  9.  
  10. 	private static int[] doItWithEquals(String[] entries) {
  11. 		int[] results = new int[entries.length];
  12. 		for (int i = 0; i < entries.length; ++i) {
  13. 			results[i] = -1;
  14. 			for (int j = 0; j < ourStrings.length; ++j) {
  15. 				if (ourStrings[j].equals(entries[i])) {
  16. 					results[i] = j;
  17. 					break;
  18. 				}
  19. 			}
  20. 		}
  21. 		return results;
  22. 	}
  23.  
  24. 	private static int[] doItWithBinarySearch(String[] entries) {
  25. 		int[] results = new int[entries.length];
  26. 		for (int i = 0; i < entries.length; ++i) {
  27. 			results[i] = Arrays.binarySearch(ourStrings, entries[i]);
  28. 		}
  29. 		return results;
  30. 	}
  31.  
  32. 	private static int[] doItWithReferences(String[] entries) {
  33. 		int[] results = new int[entries.length];
  34. 		for (int i = 0; i < entries.length; ++i) {
  35. 			results[i] = -1;
  36. 			for (int j = 0; j < ourStrings.length; ++j) {
  37. 				if (ourStrings[j] == entries[i]) {
  38. 					results[i] = j;
  39. 					break;
  40. 				}
  41. 			}
  42. 		}
  43. 		return results;
  44. 	}
  45.  
  46. 	private static String[] generateList(int size) {
  47. 		String[] result = new String[size];
  48. 		for (int i = 0; i < size; ++i) {
  49. 			result[i] = ourStrings[rng.nextInt(ourStrings.length)];
  50. 		}
  51. 		return result;
  52. 	}
  53.  
  54. 	public static void main(String[] s) {
  55. 		long totalForReferences = 0;
  56. 		long totalForEquals = 0;
  57. 		long totalForSearch = 0;
  58. 		int iterationCount = 1000;
  59.  
  60. 		for (int i = 0; i < iterationCount; ++i) {
  61. 			String[] testData = generateList(10000);
  62.  
  63. 			long start = System.nanoTime();
  64. 			int[] resultsWithReferences = doItWithReferences(testData);
  65. 			totalForReferences += System.nanoTime() - start;
  66.  
  67. 			start = System.nanoTime();
  68. 			int[] resultsWithEquals = doItWithEquals(testData);
  69. 			totalForEquals += System.nanoTime() - start;
  70.  
  71. 			start = System.nanoTime();
  72. 			int[] resultsWithBinarySearch = doItWithBinarySearch(testData);
  73. 			totalForSearch += System.nanoTime() - start;
  74.  
  75. 			if (
  76. 				!Arrays.equals(resultsWithReferences, resultsWithEquals) ||
  77. 				!Arrays.equals(resultsWithReferences, resultsWithBinarySearch)
  78. 			) {
  79. 				throw new AssertionError("Results don't match");
  80. 			}
  81. 		}
  82. 		long referencesTime = totalForReferences / iterationCount;
  83. 		long equalsTime = totalForEquals / iterationCount;
  84. 		long searchTime = totalForSearch / iterationCount;
  85.  
  86. 		System.out.printf(
  87. 			"References: %d ns\nEquals: %d ns\nBinary search: %d ns\n",
  88. 			referencesTime, equalsTime, searchTime
  89. 		);
  90. 	}
  91. }
Success #stdin #stdout 1.91s 380224KB
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Standard input is empty
stdout
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References: 167643 ns
Equals: 356585 ns
Binary search: 629974 ns
https://ideone.com/e4A5fG
language:
Java (HotSpot 12)
created:
9 years ago
visibility:
public

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