Simple Implementation of Breadth First Search Algorithm

App.java

package breadfirstserach;

public class App {

	public static void main(String[] args) {
		BFS bfs = new BFS();
		
		Node node1 = new Node(1);
		Node node2 = new Node(2);
		Node node3 = new Node(3);
		Node node4 = new Node(4);
		Node node5 = new Node(5);
		Node node6 = new Node(6);
		
		
		/**
		 * Create our adjacenyList
		 */
		
		node1.addAdjacentNodes(node2);
		node1.addAdjacentNodes(node3);
		node1.addAdjacentNodes(node6);
		
		node2.addAdjacentNodes(node1);
		node2.addAdjacentNodes(node3);
		node2.addAdjacentNodes(node4);
		
		node3.addAdjacentNodes(node1);
		node3.addAdjacentNodes(node2);
		node3.addAdjacentNodes(node4);
		node3.addAdjacentNodes(node5);
		
		node4.addAdjacentNodes(node2);
		node4.addAdjacentNodes(node3);
		node4.addAdjacentNodes(node5);
		node4.addAdjacentNodes(node6);
		
		node5.addAdjacentNodes(node3);
		node5.addAdjacentNodes(node4);
		node5.addAdjacentNodes(node6);
		
		node6.addAdjacentNodes(node1);
		node6.addAdjacentNodes(node4);
		node6.addAdjacentNodes(node5);
		
		bfs.bfs(node5);
	}

}

BFS.java

package breadfirstserach;

import java.util.LinkedList;
import java.util.Queue;

public class BFS {
	
	public void bfs (Node root){
		// Our FIFO structure
		// A queue is a LinkedList
		// no need to reinvent the wheel
		Queue <Node> queue = new LinkedList();
		
		/*
		 * We need to set our root node as visited to avoid
		 * an infinite loop, then
		 * add the node to our queue
		 */
		root.setVisited(true);
		queue.add(root);
		
		/*
		 * While our queue is not empty
		 * 1. remove current node in the queue
		 * 2. Check if the node has been visited, if not then
		 * 3. process the node by setting it's 
		 *    bool value to True, then adding its 
		 *    adjacent nodes to the adjacency list 
		 */
		while (!queue.isEmpty()) {
			Node currentVertex = queue.remove();
			System.out.println(currentVertex + " ");
			
			for (Node v : currentVertex.getAdjList()) {
				if (!v.isVisited()) {
					v.setVisited(true);
					queue.add(v);
				}
			}
		}
	}
}

Node.java

package breadfirstserach;

// import basic data structures
import java.util.ArrayList; 
import java.util.List;

public class Node {
	
	public int data;               // random data type that our vertex will hole
	public boolean visited;        // checks if our node has been visited
	public List <Node> adjList;    // list of vertices
	
	
	// constructor
	// initiate our instances with the data below
	public Node(int data) {
		this.data = data;
		this.adjList = new ArrayList();
	}

	public int getData() {
		return data;
	}

	public void setData(int data) {
		this.data = data;
	}

	public boolean isVisited() {
		return visited;
	}

	public void setVisited(boolean visited) {
		this.visited = visited;
	}

	public List<Node> getAdjList() {
		return adjList;
	}

	public void setAdjList(List <Node> adjList) {
		this.adjList = adjList;
	}
	
	@Override
	public String toString() {
		return ""+ this.data;
	}
	
	// add adjacent nodes to our adjList
	public void addAdjacentNodes(Node vertex) {
		this.adjList.add(vertex);
	}
	
}