From 0d07e421ff2564c63923c9be1b80519b618787bc Mon Sep 17 00:00:00 2001
From: shouvikbhattacharya <shouvikbhattacharya@outlook.com>
Date: Thu, 14 Dec 2017 20:15:00 +0530
Subject: [PATCH] BAEL-1433: Commit changes for treeset article.

---
 .../baeldung/collection/WhenUsingTreeSet.java | 105 ++++++++++++++++++
 1 file changed, 105 insertions(+)
 create mode 100644 core-java/src/test/java/com/baeldung/collection/WhenUsingTreeSet.java

diff --git a/core-java/src/test/java/com/baeldung/collection/WhenUsingTreeSet.java b/core-java/src/test/java/com/baeldung/collection/WhenUsingTreeSet.java
new file mode 100644
index 0000000000..48aff4d437
--- /dev/null
+++ b/core-java/src/test/java/com/baeldung/collection/WhenUsingTreeSet.java
@@ -0,0 +1,105 @@
+package com.baeldung.collection;
+
+import java.util.ConcurrentModificationException;
+import java.util.Iterator;
+import java.util.Set;
+import java.util.TreeSet;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+public class WhenUsingTreeSet {
+
+    @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());
+    }
+}