Do inorder traversal on a binary tree in java.

Hello there.

In this article, we will be traversing a binary tree, and we also print the data stored in those node.

In the inorder traversal, we print the left child – root – right child.

Here is simple recursive algorithm to do that.

1. go to left child – print the left child
2. print the root
3. go to right child – print the right child

Recursion can be a little difficult to understand. But, that’s ok, no one understands that in the beginning.

And, we also have to add a termination case to end the recursion. Because, we do not want to blow out the stack

The recursion terminator.

if (head == null) return ;

Inorder Traversal :-

//print head between left and right childs
    public static void inorder(BinaryTreeNode head) {
    if (head == null) return ;
    
    inorder(head.left);
    System.out.println(head.name);
    inorder(head.right);
}

Let us write a test code to use the above function.

public class BinaryTreeTraversal {

    public static void main(String  ... args) {
        BinaryTreeNode head = CreateBinaryTree.createCompleteBinaryTree('A', 'B', 'Z', 'E', 'P', 'Q');
    
        System.out.println("--InOrder--");
        inorder(head);
    }

}

We are using BinaryTreeNode as a node for binary tree and we are using utility function -which creates a binary tree is defined in this article – here.

The output of above code.

--InOrder--
E
B
P
A
Q
Z

So, we just traversed the binary tree in inorder.

thanks for reading.. bye for now.. 🙂