Java Program to Implement Vlist

This is a Java Program to implement a VList. VList is a persistent data structure that combines the fast indexing of arrays with the easy extension of cons-based (or singly linked) linked lists.

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

```
/*
```
```
 *  Java Program to Implement VList
```
```
 */
```
```
 
```
```
import java.util.Scanner;        
```
```
 
```
```
/*  Class Node  */
```
```
class VListNode
```
```
{
```
```
    VListNode next, prev;
```
```
    int numElements;
```
```
    int array[];
```
```
 
```
```
    /* Constructor */
```
```
    public VListNode(int n)
```
```
    {
```
```
        next = null;
```
```
        prev = null;
```
```
        numElements = 0;
```
```
        array = new int[n];        
```
```
    }
```
```
}
```
```
 
```
```
/* Class VList */
```
```
class VList
```
```
{
```
```
    private VListNode start;
```
```
    private VListNode end;
```
```
    private int nodeNumber;
```
```
    private int size;
```
```
 
```
```
    /* Constructor */
```
```
    public VList()
```
```
    {
```
```
        start = null;
```
```
        end = null;
```
```
        nodeNumber = 0;    
```
```
        size = 0;    
```
```
    }
```

    /*  Function to check if list is empty  */

```
    public boolean isEmpty()
```
```
    {
```
```
        return start == null;
```
```
    }
```

    /*  Function to get size of list  */

```
    public int getSize()
```
```
    {
```
```
        return size;
```
```
    }  
```
```
    /* Function to clear list */
```
```
    public void makeEmpty()
```
```
    {
```
```
        start = null;
```
```
        end = null;
```
```
        nodeNumber = 0;
```
```
        size = 0;
```
```
    }
```
```
    /* Function to insert element */
```
```
    public void insert(int x)
```
```
    {
```
```
        size++;
```

        int n = (int) Math.pow(2, nodeNumber);

```
        if (start == null)
```
```
        {
```
```
            start = new VListNode(n);
```
```
            start.array[0] = x;
```
```
            start.numElements++;
```
```
            end = start;
```
```
            return;
```
```
        }
```
```
        if (end.numElements + 1 <= n)
```
```
        {
```

            end.array[end.numElements] = x;

            end.numElements++;

```
        }
```
```
        else
```
```
        {
```
```
            nodeNumber++;
```

            n = (int) Math.pow(2, nodeNumber);

            VListNode nptr = new VListNode(n);

```
            nptr.array[0] = x;
```
```
            nptr.numElements++;
```
```
            nptr.prev = end;
```
```
            end.next = nptr;
```

            end = nptr;

```
        }        
```
```
    }
```
```
    /* Function to get kth element */
```
```
    public int kthElement(int k)
```
```
    {
```
```
        if (k < 1 || k > size)
```

            throw new IndexOutOfBoundsException("No element present");

```
        k--;
```
```
        VListNode ptr = start;
```
```
        while (k >= ptr.numElements)
```
```
        {
```
```
            k -= ptr.numElements;
```
```
            ptr = ptr.next;
```
```
        }
```
```
        return ptr.array[k];
```
```
    }
```
```
    /* Function to display list */
```
```
    public void display()
```
```
    {
```
```
        System.out.print("\nVList = ");
```
```
        if (size == 0) 
```
```
        {
```

            System.out.print("empty\n");

```
            return;
```
```
        }
```
```
        System.out.println();
```
```
        VListNode ptr = start;
```
```
        int num = 0;
```
```
        while (ptr != null)
```
```
        {
```

            for (int i = 0; i < ptr.numElements; i++)

                System.out.print(ptr.array[i] +" ");

            System.out.println();

```
            ptr = ptr.next;
```
```
            num++;
```
```
        }
```
```
    }
```
```
 
```
```
}
```
```
 
```
```
/*  Class VListTest */
```
```
public class VListTest
```
```
{    
```

    public static void main(String[] args)

```
    {             
```

        Scanner scan = new Scanner(System.in);

        System.out.println("VList Test\n");

```
 
```

        /* Creating object of class VList */

```
        VList vl = new VList(); 
```
```
 
```
```
        char ch;
```
```
        /*  Perform list operations */
```
```
        do
```
```
        {
```

            System.out.println("\nVList Operations\n");

            System.out.println("1. insert");

            System.out.println("2. kth element");

            System.out.println("3. check empty");

            System.out.println("4. get size");

            System.out.println("5. clear");

            int choice = scan.nextInt();

```
            switch (choice)
```
```
            {
```
```
            case 1 :  
```

                System.out.println("Enter integer element to insert");

                vl.insert( scan.nextInt() );

```
                break;  
```
```
            case 2 :  
```
```
                try
```
```
                {
```

                    System.out.println("Enter postion");

                    System.out.println("\nK-th element = "+ vl.kthElement( scan.nextInt() ));

```
                }
```
```
                catch (Exception e)
```
```
                {
```

                    System.out.println("\nError : "+ e.getMessage() );

```
                }
```

                break;

```
            case 3 : 
```

                System.out.println("Empty status = "+ vl.isEmpty());

                break;

```
            case 4 : 
```

                System.out.println("Size = "+ vl.getSize() +" \n");

```
                break; 
```
```
            case 5 : 
```

                System.out.println("List Cleared\n");

```
                vl.makeEmpty();
```

                break;

```
            default : 
```

                System.out.println("Wrong Entry \n ");

```
                break;   
```
```
            }
```
```
            /*  Display List */ 
```
```
            vl.display();
```
```
 
```

            System.out.println("\nDo you want to continue (Type y or n) \n");

            ch = scan.next().charAt(0);

        } while (ch == 'Y'|| ch == 'y');

```
    }
```
```
}
```

VList Test
 
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
28
 
VList =
28
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
5
 
VList =
28
5
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
19
 
VList =
28
5 19
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
63
 
VList =
28
5 19
63
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
14
 
VList =
28
5 19
63 14
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
7
 
VList =
28
5 19
63 14 7
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
19
 
VList =
28
5 19
63 14 7 19
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
70
 
VList =
28
5 19
63 14 7 19
70
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
1
 
VList =
28
5 19
63 14 7 19
70 1
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
5
 
VList =
28
5 19
63 14 7 19
70 1 5
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
90
 
VList =
28
5 19
63 14 7 19
70 1 5 90
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
67
 
VList =
28
5 19
63 14 7 19
70 1 5 90 67
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
87
 
VList =
28
5 19
63 14 7 19
70 1 5 90 67 87
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
2
 
VList =
28
5 19
63 14 7 19
70 1 5 90 67 87 2
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
99
 
VList =
28
5 19
63 14 7 19
70 1 5 90 67 87 2 99
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
1
Enter integer element to insert
24
 
VList =
28
5 19
63 14 7 19
70 1 5 90 67 87 2 99
24
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
2
Enter postion
5
 
K-th element = 14
 
VList =
28
5 19
63 14 7 19
70 1 5 90 67 87 2 99
24
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
4
Size = 16
 
 
VList =
28
5 19
63 14 7 19
70 1 5 90 67 87 2 99
24
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
5
List Cleared
 
 
VList = empty
 
Do you want to continue (Type y or n)
 
y
 
VList Operations
 
1. insert
2. kth element
3. check empty
4. get size
5. clear
3
Empty status = true
 
VList = empty
 
Do you want to continue (Type y or n)
 
n

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