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Merge pull request #3243 from shouvikbhattacharya/BAEL-1433 

Bael 1433: Guide to TreeSet in Java
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Carsten Gräf 2017-12-16 12:47:39 +01:00 committed by GitHub
parent 5055f348b6 ef4b560965
commit 1d73d59d93
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core-java/src/test/java/com/baeldung/collection/WhenUsingTreeSet.java Normal file
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package com.baeldung.collection;
import java.util.Comparator;
import java.util.ConcurrentModificationException;
import java.util.Iterator;
import java.util.NavigableSet;
import java.util.Set;
import java.util.SortedSet;
import java.util.TreeSet;
import org.junit.Assert;
import org.junit.Test;
public class WhenUsingTreeSet {
private static class Element {
private Integer id;
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
@Override
public String toString() {
// TODO Auto-generated method stub
return id.toString();
}
}
private Comparator<Element> comparator = (ele1, ele2) -> {
return ele1.getId()
.compareTo(ele2.getId());
};
@Test
public void whenAddingElement_shouldAddElement() {
Set<String> treeSet = new TreeSet<>();
Assert.assertTrue(treeSet.add("String Added"));
}
@Test
public void whenCheckingForElement_shouldSearchForElement() {
Set<String> treeSetContains = new TreeSet<>();
treeSetContains.add("String Added");
Assert.assertTrue(treeSetContains.contains("String Added"));
}
@Test
public void whenRemovingElement_shouldRemoveElement() {
Set<String> removeFromTreeSet = new TreeSet<>();
removeFromTreeSet.add("String Added");
Assert.assertTrue(removeFromTreeSet.remove("String Added"));
}
@Test
public void whenClearingTreeSet_shouldClearTreeSet() {
Set<String> clearTreeSet = new TreeSet<>();
clearTreeSet.add("String Added");
clearTreeSet.clear();
Assert.assertTrue(clearTreeSet.isEmpty());
}
@Test
public void whenCheckingTheSizeOfTreeSet_shouldReturnThesize() {
Set<String> treeSetSize = new TreeSet<>();
treeSetSize.add("String Added");
Assert.assertEquals(1, treeSetSize.size());
}
@Test
public void whenCheckingForEmptyTreeSet_shouldCheckForEmpty() {
Set<String> emptyTreeSet = new TreeSet<>();
Assert.assertTrue(emptyTreeSet.isEmpty());
}
@Test
public void whenIteratingTreeSet_shouldIterateTreeSetInAscendingOrder() {
Set<String> treeSet = new TreeSet<>();
treeSet.add("First");
treeSet.add("Second");
treeSet.add("Third");
Iterator<String> itr = treeSet.iterator();
while (itr.hasNext()) {
System.out.println(itr.next());
}
}
@Test
public void whenIteratingTreeSet_shouldIterateTreeSetInDescendingOrder() {
TreeSet<String> treeSet = new TreeSet<>();
treeSet.add("First");
treeSet.add("Second");
treeSet.add("Third");
Iterator<String> itr = treeSet.descendingIterator();
while (itr.hasNext()) {
System.out.println(itr.next());
}
}
@Test(expected = ConcurrentModificationException.class)
public void whenModifyingTreeSetWhileIterating_shouldThrowException() {
Set<String> treeSet = new TreeSet<>();
treeSet.add("First");
treeSet.add("Second");
treeSet.add("Third");
Iterator<String> itr = treeSet.iterator();
while (itr.hasNext()) {
itr.next();
treeSet.remove("Second");
}
}
@Test
public void whenRemovingElementUsingIterator_shouldRemoveElement() {
Set<String> treeSet = new TreeSet<>();
treeSet.add("First");
treeSet.add("Second");
treeSet.add("Third");
Iterator<String> itr = treeSet.iterator();
while (itr.hasNext()) {
String element = itr.next();
if (element.equals("Second"))
itr.remove();
}
Assert.assertEquals(2, treeSet.size());
}
@Test(expected = NullPointerException.class)
public void whenAddingNullToNonEmptyTreeSet_shouldThrowException() {
Set<String> treeSet = new TreeSet<>();
treeSet.add("First");
treeSet.add(null);
}
@Test
public void whenCheckingFirstElement_shouldReturnFirstElement() {
TreeSet<String> treeSet = new TreeSet<>();
treeSet.add("First");
Assert.assertEquals("First", treeSet.first());
}
@Test
public void whenCheckingLastElement_shouldReturnLastElement() {
TreeSet<String> treeSet = new TreeSet<>();
treeSet.add("First");
treeSet.add("Last");
Assert.assertEquals("Last", treeSet.last());
}
@Test
public void whenUsingComparator_shouldSortAndInsertElements() {
Set<Element> treeSet = new TreeSet<>(comparator);
Element ele1 = new Element();
ele1.setId(100);
Element ele2 = new Element();
ele2.setId(200);
treeSet.add(ele1);
treeSet.add(ele2);
System.out.println(treeSet);
}
@Test
public void whenUsingHeadSet_shouldReturnElementsLessThanSpecifiedElement() {
Set<Element> treeSet = new TreeSet<>(comparator);
Element ele1 = new Element();
ele1.setId(100);
Element ele2 = new Element();
ele2.setId(200);
treeSet.add(ele1);
treeSet.add(ele2);
System.out.println(treeSet);
}
@Test
public void whenUsingSubSet_shouldReturnSubSetElements() {
SortedSet<Integer> treeSet = new TreeSet<>();
treeSet.add(1);
treeSet.add(2);
treeSet.add(3);
treeSet.add(4);
treeSet.add(5);
treeSet.add(6);
Set<Integer> subSet = treeSet.subSet(2, 6);
System.out.println(subSet);
}
@Test
public void whenUsingHeadSet_shouldReturnHeadSetElements() {
SortedSet<Integer> treeSet = new TreeSet<>();
treeSet.add(1);
treeSet.add(2);
treeSet.add(3);
treeSet.add(4);
treeSet.add(5);
treeSet.add(6);
Set<Integer> subSet = treeSet.headSet(6);
Assert.assertEquals(subSet, treeSet.subSet(1, 6));
}
@Test
public void whenUsingTailSet_shouldReturnTailSetElements() {
NavigableSet<Integer> treeSet = new TreeSet<>();
treeSet.add(1);
treeSet.add(2);
treeSet.add(3);
treeSet.add(4);
treeSet.add(5);
treeSet.add(6);
Set<Integer> subSet = treeSet.tailSet(3);
Assert.assertEquals(subSet, treeSet.subSet(3, true, 6, true));
}
}