Java Program to Check whether Undirected Graph is Connected using DFS

Code:

import java.util.InputMismatchException;
import java.util.Scanner;
import java.util.Stack;

public class UndirectedConnectivityDfs
{
    private Stack stack;

    public UndirectedConnectivityDfs() 
    {
        stack = new Stack();
    } 

    public void dfs(int adjacency_matrix[][], int source)
    {
        int number_of_nodes = adjacency_matrix[source].length - 1;
        int visited[] = new int[number_of_nodes + 1];
        int element = source;
        int i = source;
        visited[source] = 1;
        stack.push(source);

        while (!stack.isEmpty())
        {
            element = stack.peek();
            i = element;
    while (i <= number_of_nodes)
    {
              if (adjacency_matrix[element][i] == 1 && visited[i] == 0)
        {
                    stack.push(i);
                    visited[i] = 1;
                    element = i;
                    i = 1;
            continue;
                }
                i++;
    }
            stack.pop();
        }
        boolean connected = false;

        for (int vertex = 1; vertex <= number_of_nodes; vertex++)
        {
            if (visited[vertex] == 1) 
            {
                connected = true;
            } else
            {
                connected = false;
                break;
            }
        }

        if (connected)
        {
            System.out.println("The graph is connected");
}else
        {
            System.out.println("The graph is disconnected");
        }
    }

    public static void main(String...arg)
    {
        int number_of_nodes, source;
        Scanner scanner = null;
  try
        {
    System.out.println("Enter the number of nodes in the graph");
            scanner = new Scanner(System.in);
            number_of_nodes = scanner.nextInt();

    int adjacency_matrix[][] = new int[number_of_nodes + 1][number_of_nodes + 1];
    System.out.println("Enter the adjacency matrix");
    for (int i = 1; i <= number_of_nodes; i++)
       for (int j = 1; j <= number_of_nodes; j++)
                   adjacency_matrix[i][j] = scanner.nextInt();

        for (int i = 1; i <= number_of_nodes; i++)
            {
                for (int j = 1; j <= number_of_nodes; j++)
                {
                     if (adjacency_matrix[i][j] == 1 && adjacency_matrix[j][i] == 0)
                     {
                         adjacency_matrix[j][i] = 1;
                     }
                }
            }

    System.out.println("Enter the source for the graph");
            source = scanner.nextInt(); 

            UndirectedConnectivityDfs undirectedConnectivity= new UndirectedConnectivityDfs();
            undirectedConnectivity.dfs(adjacency_matrix, source);

        }catch(InputMismatchException inputMismatch)
        {
            System.out.println("Wrong Input format");
        }
        scanner.close();
    }
}



Output:

Enter the number of nodes in the graph
5
Enter the adjacency matrix
0 1 0 1 0
0 0 1 0 0
0 0 0 0 0
0 1 0 0 0
0 0 0 0 0
Enter the source for the graph
1
The graph is disconnected



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