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| 1 | +package com.baeldung.java.set; |
| 2 | + |
| 3 | +import static org.junit.Assert.assertEquals; |
| 4 | +import static org.junit.Assert.assertTrue; |
| 5 | + |
| 6 | +import java.util.ConcurrentModificationException; |
| 7 | +import java.util.HashSet; |
| 8 | +import java.util.Iterator; |
| 9 | +import java.util.Set; |
| 10 | +import java.util.TreeSet; |
| 11 | + |
| 12 | +import org.junit.Test; |
| 13 | + |
| 14 | +public class SetTest { |
| 15 | + |
| 16 | + @Test |
| 17 | + public void givenTreeSet_whenRetrievesObjects_thenNaturalOrder() { |
| 18 | + Set<String> set = new TreeSet<>(); |
| 19 | + set.add("Baeldung"); |
| 20 | + set.add("is"); |
| 21 | + set.add("Awesome"); |
| 22 | + assertEquals(3, set.size()); |
| 23 | + assertTrue(set.iterator() |
| 24 | + .next() |
| 25 | + .equals("Awesome")); |
| 26 | + } |
| 27 | + |
| 28 | + @Test(expected = NullPointerException.class) |
| 29 | + public void givenTreeSet_whenAddNullObject_thenNullPointer() { |
| 30 | + Set<String> set = new TreeSet<>(); |
| 31 | + set.add("Baeldung"); |
| 32 | + set.add("is"); |
| 33 | + set.add(null); |
| 34 | + } |
| 35 | + |
| 36 | + @Test |
| 37 | + public void givenHashSet_whenAddNullObject_thenOK() { |
| 38 | + Set<String> set = new HashSet<>(); |
| 39 | + set.add("Baeldung"); |
| 40 | + set.add("is"); |
| 41 | + set.add(null); |
| 42 | + assertEquals(3, set.size()); |
| 43 | + } |
| 44 | + |
| 45 | + @Test |
| 46 | + public void givenHashSetAndTreeSet_whenAddObjects_thenHashSetIsFaster() { |
| 47 | + Set<String> set = new HashSet<>(); |
| 48 | + long startTime = System.nanoTime(); |
| 49 | + set.add("Baeldung"); |
| 50 | + set.add("is"); |
| 51 | + set.add("Awesome"); |
| 52 | + long endTime = System.nanoTime(); |
| 53 | + long duration1 = (endTime - startTime); |
| 54 | + |
| 55 | + Set<String> set2 = new TreeSet<>(); |
| 56 | + startTime = System.nanoTime(); |
| 57 | + set2.add("Baeldung"); |
| 58 | + set2.add("is"); |
| 59 | + set2.add("Awesome"); |
| 60 | + endTime = System.nanoTime(); |
| 61 | + long duration2 = (endTime - startTime); |
| 62 | + assertTrue(duration1 < duration2); |
| 63 | + } |
| 64 | + |
| 65 | + @Test |
| 66 | + public void givenHashSetAndTreeSet_whenAddDuplicates_thenOnlyUnique() { |
| 67 | + Set<String> set = new HashSet<>(); |
| 68 | + set.add("Baeldung"); |
| 69 | + set.add("Baeldung"); |
| 70 | + assertTrue(set.size() == 1); |
| 71 | + |
| 72 | + Set<String> set2 = new TreeSet<>(); |
| 73 | + set2.add("Baeldung"); |
| 74 | + set2.add("Baeldung"); |
| 75 | + assertTrue(set2.size() == 1); |
| 76 | + } |
| 77 | + |
| 78 | + @Test(expected = ConcurrentModificationException.class) |
| 79 | + public void givenHashSet_whenModifyWhenIterator_thenFailFast() { |
| 80 | + Set<String> set = new HashSet<>(); |
| 81 | + set.add("Baeldung"); |
| 82 | + Iterator<String> it = set.iterator(); |
| 83 | + |
| 84 | + while (it.hasNext()) { |
| 85 | + set.add("Awesome"); |
| 86 | + it.next(); |
| 87 | + } |
| 88 | + } |
| 89 | +} |
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