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Java program to perform preorder tree traversal

Comprehensive Java Examples

In this example, we will learn how to perform preorder tree traversal in a Java program.

Example: Java program to perform preorder tree traversal

class Node {
  int item;
  Node left, right;
  public Node(int key) {
  item = key;
  left = right = null;
  }
}
class Tree {
  //The root of Tree
  Node root;
  Tree() {
  root = null;
  }
  void preorder(Node node) {
    if (node == null)
      return;
    //Traverse the root node
    System.out.print(node.item + ->
    //Traverse the left child elements
    preorder(node.left);
    //Traverse Right Sub-element
    preorder(node.right);
  }
  public static void main(String[] args) {
    //Creating Tree Object
    Tree tree = new Tree();
    //Creating Tree Nodes
    tree.root = new Node(1);
    tree.root.left = new Node(12);
    tree.root.right = new Node(9);
    tree.root.left.left = new Node(5);
    tree.root.left.right = new Node(6);
    //Preorder Tree Traversal
    System.out.println("\nPreorder Tree Traversal \t");
    tree.preorder(tree.root);
  }
}
Preorder Traversal of Tree

Output Result

Preorder Tree Traversal
1->12->5->6->9->

In the above example, we have implemented the tree data structure in Java. Here, we are performing the preorder traversal of the tree.

Recommended Reading:

Comprehensive Java Examples