programming-examples/java/Data_Structures/Java Program to Implement VList.java

/*
 *  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 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