Contoh 1 : Coding Java Binary Tree (Preorder, Inorder, Postorder)

package binarytree;
/**
 *
 *
 */
import java.util.Stack;
public class BinaryTree3 {
 public static class TreeNode
 {
  int data;
  TreeNode left;
  TreeNode right;
  TreeNode(char data)
  {
   this.data=data;
  }
 }
 // Recursive Solution
 public void preorder(TreeNode root) {
    if(root !=  null) {
   //Visit the node-Printing the node data  
      System.out.printf("%c ",root.data);
      preorder(root.left);
      preorder(root.right);
    }
  }
 // Recursive Solution
 public void postOrder(TreeNode root) {
  if(root !=  null) {
   postOrder(root.left);
   postOrder(root.right);
   //Visit the node by Printing the node data  
   System.out.printf("%c ",root.data);
  }
 }
 // Recursive Solution
 public void inOrder(TreeNode root) {
  if(root !=  null) {
   inOrder(root.left);
   //Visit the node by Printing the node data  
   System.out.printf("%c ",root.data);
   inOrder(root.right);
  }
 }
 public static void main(String[] args)
 {
  BinaryTree3 bi=new BinaryTree3();
  // Creating a binary tree
  TreeNode rootNode=createBinaryTree();
  System.out.println("Tampilan PreOrder Tree :");
  bi.preorder(rootNode);
  System.out.println();
  System.out.println("-------------------------");
  System.out.println("Tampilan PostOrder Tree :");
  bi.postOrder(rootNode);
  System.out.println();
  System.out.println("-------------------------");
  System.out.println("Tampilan InOrder Tree:");
  bi.inOrder(rootNode);
 }
 public static TreeNode createBinaryTree()
 {  
  TreeNode rootNode =new TreeNode('A');
  TreeNode nodeB=new TreeNode('B');
  TreeNode nodeC=new TreeNode('C');
  TreeNode nodeD=new TreeNode('D');
  TreeNode nodeE=new TreeNode('E');
  TreeNode nodeF=new TreeNode('F');
  TreeNode nodeI=new TreeNode('I');
  TreeNode nodeJ=new TreeNode('J');
  TreeNode nodeK=new TreeNode('K');

  rootNode.left=nodeB;
  rootNode.right=nodeC;
  nodeB.left=nodeD;
  nodeB.right=nodeE;
  nodeC.left=nodeF;
  nodeF.left=nodeI;
  nodeF.right=nodeJ;
  nodeI.left=nodeK;
  return rootNode;
 }
}

Tampilan Output :