﻿ Java: Postorder traversal of its node of a binary tree # Java Exercises: Get the Postorder traversal of its nodes' values of a given a binary tree

## Java Basic: Exercise-127 with Solution

Write a Java program to get the Postorder traversal of its nodes' values of a given a binary tree.

Sample Binary Tree Postorder Traversal: Sample Solution:

Java Code:

``````class Node
{
int key;
Node left, right;

public Node(int item)
{
key = item;
left = right = null;
}
}

class BinaryTree
{
// Root of Binary Tree
Node root;

BinaryTree()
{
root = null;
}

// Print the nodes of binary tree

void print_Postorder(Node node)
{
if (node == null)
return;

print_Postorder(node.left);

print_Postorder(node.right);

System.out.print(node.key + " ");
}

// Wrappers over above recursive functions
void print_Postorder()
{
print_Postorder(root);
}
public static void main(String[] args)
{
BinaryTree tree = new BinaryTree();
tree.root = new Node(55);
tree.root.left = new Node(21);
tree.root.right = new Node(80);
tree.root.left.left = new Node(9);
tree.root.left.right = new Node(29);
tree.root.right.left = new Node(76);
tree.root.right.right = new Node(91);

System.out.println("\nPostorder traversal of binary tree is: ");
tree.print_Postorder();
}
}
```
```

Sample Output:

```Postorder traversal of binary tree is:
9 29 21 76 91 80 55
```

Flowchart: Java Code Editor:

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## Java: Tips of the Day

getEnumMap

Converts to enum to Map where key is the name and value is Enum itself.

```public static <E extends Enum<E>> Map<String, E> getEnumMap(final Class<E> enumClass) {
return Arrays.stream(enumClass.getEnumConstants())
.collect(Collectors.toMap(Enum::name, Function.identity()));
}
```

Ref: https://bit.ly/3xXcFZt