How to Implement DFS & BFS Traversal in Java

Depth-first search (DFS) and best-first search (BFS) are two traversals you can run on Java tree structures. They start at a specified node and branch out until they find the search object. The only difference is the directionality: DFS searches down from the node, BFS searches horizontally to neighboring nodes. Implementing DFS and BFS traversals is relatively simple, because, though the code is long, there are only a couple places where it needs to be customized for your data.

Instructions

1. Open your Java code.

2. Copy and paste the following where you want the traversal to run:
   public void TRAV()
   {
   Stack s=new Stack();
   s.push(this.rootNode);
   rootNode.PROP;
   printNode(rootNode);
   while(!s.isEmpty())
   {
   Node n=(Node)s.peek();
   Node child=getUnvisitedChildNode(n);
   if(child!=null)
   {
   child.visited=true;
   printNode(child);
   s.push(child);
   }
   else
   {
   s.pop();
   }
   }
   clearNodes();
   }

3. Replace “TRAV” with either “dfs” or “bfs.”

4. Replace “PROP” with your search property. This can be any Java condition, using regular Java code.

5. Run the code. It will perform the DFS/BFS traversal and display the results in a new window when it finishes.

References

• The Code Project: Introduction to Graph With Breadth First Search (BFS) and Depth First Search (DFS) Traversal Implemented in JAVA