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HashSet and TreeSet comparison (#1698)

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maibin 2017-04-25 03:29:26 +02:00 committed by KevinGilmore
parent 91552e127d
commit 4eb3f44b14
1 changed files with 89 additions and 0 deletions
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core-java/src/test/java/com/baeldung/java/set/SetTest.java Normal file
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package com.baeldung.java.set;
import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertTrue;
import java.util.ConcurrentModificationException;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import java.util.TreeSet;
import org.junit.Test;
public class SetTest {
@Test
public void givenTreeSet_whenRetrievesObjects_thenNaturalOrder() {
Set<String> set = new TreeSet<>();
set.add("Baeldung");
set.add("is");
set.add("Awesome");
assertEquals(3, set.size());
assertTrue(set.iterator()
.next()
.equals("Awesome"));
}
@Test(expected = NullPointerException.class)
public void givenTreeSet_whenAddNullObject_thenNullPointer() {
Set<String> set = new TreeSet<>();
set.add("Baeldung");
set.add("is");
set.add(null);
}
@Test
public void givenHashSet_whenAddNullObject_thenOK() {
Set<String> set = new HashSet<>();
set.add("Baeldung");
set.add("is");
set.add(null);
assertEquals(3, set.size());
}
@Test
public void givenHashSetAndTreeSet_whenAddObjects_thenHashSetIsFaster() {
Set<String> set = new HashSet<>();
long startTime = System.nanoTime();
set.add("Baeldung");
set.add("is");
set.add("Awesome");
long endTime = System.nanoTime();
long duration1 = (endTime - startTime);
Set<String> set2 = new TreeSet<>();
startTime = System.nanoTime();
set2.add("Baeldung");
set2.add("is");
set2.add("Awesome");
endTime = System.nanoTime();
long duration2 = (endTime - startTime);
assertTrue(duration1 < duration2);
}
@Test
public void givenHashSetAndTreeSet_whenAddDuplicates_thenOnlyUnique() {
Set<String> set = new HashSet<>();
set.add("Baeldung");
set.add("Baeldung");
assertTrue(set.size() == 1);
Set<String> set2 = new TreeSet<>();
set2.add("Baeldung");
set2.add("Baeldung");
assertTrue(set2.size() == 1);
}
@Test(expected = ConcurrentModificationException.class)
public void givenHashSet_whenModifyWhenIterator_thenFailFast() {
Set<String> set = new HashSet<>();
set.add("Baeldung");
Iterator<String> it = set.iterator();
while (it.hasNext()) {
set.add("Awesome");
it.next();
}
}
}