Java program to Implement Tree Set

This is a Java program to Implement Tree Set. A set is an abstract data structure that can store certain values, without any particular order, and no repeated values. Here Tree set maintains sorted order.

Here is the source code of the Java program to Implement Tree Set. The Java program is successfully compiled and run on a Windows system. The program output is also shown below.

/**
 * Java program to implement Tree Set
 */
 
import java.util.Scanner;    
 
/** class TreeSetNode **/
class TreeSetNode
{
    String data;
    TreeSetNode left, right;
 
    /** constructor **/
    public TreeSetNode(String data, TreeSetNode left, TreeSetNode right)
    {
        this.data  = data;
        this.left  = left;
        this.right = right;
    }    
}
 
/** class TreeSet **/
class TreeSet
{
    private TreeSetNode root;
    private int size;
 
    /** constructor **/
    public TreeSet()
    {
        root = null;
        size = 0;
    }
 
    /** function to check if empty **/
    public boolean isEmpty()
    {
        return root == null;
    }
 
    /** function to clear **/
    public void clear()
    {
        root = null;
        size = 0;
    }
 
    /** function to insert an element **/
    public void add(String ele)
    {
        root = insert(root, ele);
    }
 
    /** function to insert an element **/
    private TreeSetNode insert(TreeSetNode r, String ele)
    {
        if (r == null)
            r = new TreeSetNode(ele, null, null);
        else
        {
            if (ele.compareTo(r.data) < 0)
                r.left = insert(r.left, ele);
            else if (ele.compareTo(r.data) > 0)
                r.right = insert(r.right, ele);
        }
        return r;
    }
 
    /** Functions to count number of nodes **/
    public int countNodes()
    {
        return countNodes(root);
    }
    /** Function to count number of nodes recursively **/
    private int countNodes(TreeSetNode r)
    {
        if (r == null)
            return 0;
        else
        {
            int l = 1;
            l += countNodes(r.left);
            l += countNodes(r.right);
            return l;
        }
    }
 
    /** Functions to search for an element **/
    public boolean contains(String ele)
    {
        return contains(root, ele);
    }
    /** Function to search for an element recursively **/
    private boolean contains(TreeSetNode r, String ele)
    {
        boolean found = false;
        while ((r != null) && !found)
        {
            if (ele.compareTo(r.data) < 0)
                r = r.left;
            else if (ele.compareTo(r.data) > 0)
                r = r.right;
            else
            {
                found = true;
                break;
            }
            found = contains(r, ele);
        }
        return found;
    }
 
    /** Function to delete data **/
    public void delete(String ele)
    {
        if (isEmpty())
            System.out.println("Tree Empty");
        else if (contains(ele) == false)
            System.out.println("Error : "+ ele +" is not present");
        else
        {
            root = delete(root, ele);
            System.out.println(ele +" deleted from the tree set");
        }
    }
    /** Function to delete element **/
    private TreeSetNode delete(TreeSetNode r, String ele)
    {
        TreeSetNode p, p2, n;
        if (r.data.equals(ele))
        {
            TreeSetNode lt, rt;
            lt = r.left;
            rt = r.right;
            if (lt == null && rt == null)
                return null;
            else if (lt == null)
            {
                p = rt;
                return p;
            }
            else if (rt == null)
            {
                p = lt;
                return p;
            }
            else
            {
                p2 = rt;
                p = rt;
                while (p.left != null)
                    p = p.left;
                p.left = lt;
                return p2;
            }
        }
        if (ele.compareTo(r.data) < 0)
        {
            n = delete(r.left, ele);
            r.left = n;
        }
        else
        {
            n = delete(r.right, ele);
            r.right = n;             
        }
        return r;
    }  
 
    /** function toString() **/
    public String toString()
    {
        return "[ "+ inorder(root, "") +"]";        
    }
    private String inorder(TreeSetNode r, String str)
    {
        if (r != null)
            return str + inorder(r.left, str) + r.data +" "+ inorder(r.right, str);
        else
            return "";
    }    
}
 
/** Class TreeSetTest **/
public class TreeSetTest
{
    public static void main(String[] args)
    {                 
        Scanner scan = new Scanner(System.in);
 
        /** Creating object of TreeSetTest **/
        TreeSet ts = new TreeSet(); 
 
        System.out.println("Tree Set Test\n");          
        char ch;
        /**  Perform set operations  **/
        do    
        {
            System.out.println("\nTree Set Operations\n");
            System.out.println("1. add ");
            System.out.println("2. delete");
            System.out.println("3. contains");
            System.out.println("4. count ");
            System.out.println("5. check empty"); 
            System.out.println("6. clear"); 
 
            int choice = scan.nextInt();            
            switch (choice)
            {
            case 1 : 
                System.out.println("Enter element to insert");
                ts.add( scan.next() );                     
                break;                          
            case 2 : 
                System.out.println("Enter element to delete");
                ts.delete( scan.next() );                     
                break;                         
            case 3 : 
                System.out.println("Enter integer element to search");
                System.out.println("Search result : "+ ts.contains( scan.next() ));
                System.out.println();
                break;                                          
            case 4 : 
                System.out.println("Count = "+ ts.countNodes());
                break;     
            case 5 :  
                System.out.println("Empty status = "+ ts.isEmpty());
                break;   
            case 6 :  
                System.out.println("Tree set cleared");
                ts.clear();
                break;         
            default : 
                System.out.println("Wrong Entry \n ");
                break;   
            }
            /**  Display tree set  **/ 
            System.out.print("\nTree Set : "+ ts);
            System.out.println();
 
            System.out.println("\nDo you want to continue (Type y or n) \n");
            ch = scan.next().charAt(0);                        
        } while (ch == 'Y'|| ch == 'y');               
    }
}

Tree Set Test
 
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
5
Empty status = true
 
Tree Set : [ ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
1
Enter element to insert
mango
 
Tree Set : [ mango ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
1
Enter element to insert
strawberry
 
Tree Set : [ mango strawberry ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
1
Enter element to insert
apple
 
Tree Set : [ apple mango strawberry ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
1
Enter element to insert
pineapple
 
Tree Set : [ apple mango pineapple strawberry ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
1
Enter element to insert
orange
 
Tree Set : [ apple mango orange pineapple strawberry ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
1
Enter element to insert
jackfruit
 
Tree Set : [ apple jackfruit mango orange pineapple strawberry ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
4
Count = 6
 
Tree Set : [ apple jackfruit mango orange pineapple strawberry ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
2
Enter element to delete
jackfruit
jackfruit deleted from the tree set
 
Tree Set : [ apple mango orange pineapple strawberry ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
2
Enter element to delete
strawberry
strawberry deleted from the tree set
 
Tree Set : [ apple mango orange pineapple ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
3
Enter integer element to search
strawberry
Search result : false
 
 
Tree Set : [ apple mango orange pineapple ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
4
Count = 4
 
Tree Set : [ apple mango orange pineapple ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
5
Empty status = false
 
Tree Set : [ apple mango orange pineapple ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
6
Tree set cleared
 
Tree Set : [ ]
 
Do you want to continue (Type y or n)
 
y
 
Tree Set Operations
 
1. add
2. delete
3. contains
4. count
5. check empty
6. clear
5
Empty status = true
 
Tree Set : [ ]
 
Do you want to continue (Type y or n)
 
n