what is treeset in java

1import java.util.TreeSet;
2public class TreeSetComparatorMethodExample
3{
4   public static void main(String[] args)
5   {
6      TreeSet<Integer> ts = new TreeSet<Integer>();
7      TreeSet<Integer> comp = new TreeSet<Integer>();
8      ts.add(5);
9      ts.add(6);
10      ts.add(7);
11      ts.add(8);
12      ts.add(9);
13      ts.add(10);
14      // use comparator
15      comp = (TreeSet)ts.comparator();
16      if(comp != null)
17      {
18         for(Integer element : comp)
19         {
20            System.out.println(element + " ");
21         }
22      }
23      else
24      {
25         System.out.println("TreeSet comparator value: " + comp);
26         System.out.println("Hence it is using natural ordering.");
27      }
28   }
29}

1package MyPackage;
2  
3public class Tree { 
4    static class Node {    
5    int value; 
6        Node left, right; 
7          
8        Node(int value){ 
9            this.value = value; 
10            left = null; 
11            right = null; 
12        } 
13    } 
14       
15    public void insert(Node node, int value) {
16        if (value < node.value) { if (node.left != null) { insert(node.left, value); } else { System.out.println(" Inserted " + value + " to left of " + node.value); node.left = new Node(value); } } else if (value > node.value) {
17          if (node.right != null) {
18            insert(node.right, value);
19          } else {
20            System.out.println("  Inserted " + value + " to right of "
21                + node.value);
22            node.right = new Node(value);
23          }
24        }
25      }
26     public void traverseInOrder(Node node) {
27        if (node != null) {
28            traverseInOrder(node.left);
29            System.out.print(" " + node.value);
30            traverseInOrder(node.right);
31        }
32     }
33     
34     public static void main(String args[]) 
35    { 
36    Tree tree = new Tree();
37                Node root = new Node(5);
38                System.out.println("Binary Tree Example");
39                System.out.println("Building tree with root value " + root.value);
40                tree.insert(root, 2);
41                tree.insert(root, 4);
42                tree.insert(root, 8);
43                tree.insert(root, 6);
44                tree.insert(root, 7);
45                tree.insert(root, 3);
46                tree.insert(root, 9);
47                System.out.println("Traversing tree in order");
48                tree.traverseLevelOrder();
49                
50              }
51}

1// java treeset example
2import java.util.Iterator;
3import java.util.TreeSet;
4public class TreeSetExamples
5{
6   public static void main(String[] args)
7   {
8      TreeSet<String> ts = new TreeSet<String>();
9      ts.add("red");
10      ts.add("blue");
11      ts.add("green");
12      ts.add("red");
13      Iterator<String> iterate = ts.iterator();
14      while(iterate.hasNext())
15      {
16         System.out.println(iterate.next());
17      }
18   }
19}

1import java.util.*;
2
3// Declare the variable using the interface of the object for flexibility.
4// Non-primative data types only.
5Set<String> movies = new TreeSet<String>();
6
7movies.add(E);
8// TreeSet will be sorted by element.
9// Work with any comparable object.
10
11movies.add("The Shining");
12movies.add("Dawn of the Dead");
13movies.add("Zombieland");

1- TreeSet sorts the order and don't accept null 

1import java.util.TreeSet;
2public class TreeSetSizeMethodExample
3{
4   public static void main(String[] args)
5   {
6      TreeSet<String> ts = new TreeSet<String>();
7      ts.add("watermelon");
8      ts.add("apple");
9      ts.add("banana");
10      ts.add("grapes");
11      ts.add("mango");
12      ts.add("orange");
13      System.out.println("Given TreeSet: " + ts);
14      // print size of TreeSet
15      System.out.println("size of TreeSet is: " + ts.size());
16   }
17}
18
19
20