Answered: Compilation failed Compilation failed…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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Related questions

Question

I need help fixing this Java code to output as it's explained in the image below:

import java.util.Stack;

public class BXT {
private TreeNode root;

public void buildTree(String postfix) {
Stack<TreeNode> stack = new Stack<>();
String[] tokens = postfix.split(" ");

for (String token : tokens) {
if (isOperator(token)) {
TreeNode right = stack.pop();
TreeNode left = stack.pop();
stack.push(new TreeNode(token, left, right));
} else {
stack.push(new TreeNode(token));
}
}

root = stack.pop();
}

public double evaluateTree() {
return evaluateTree(root);
}

private double evaluateTree(TreeNode node) {
if (isOperator(node.getData())) {
double left = evaluateTree(node.getLeft());
double right = evaluateTree(node.getRight());
switch (node.getData()) {
case "+": return left + right;
case "-": return left - right;
case "*": return left * right;
case "/": return left / right;
default: throw new IllegalArgumentException("Invalid operator: " + node.getData());
}
} else {
return Double.parseDouble(node.getData());
}
}

public void infix() {
infix(root);
System.out.println();
}

private void infix(TreeNode node) {
if (node != null) {
infix(node.getLeft());
System.out.print(node.getData() + " ");
infix(node.getRight());
}
}

public void prefix() {
prefix(root);
System.out.println();
}

private void prefix(TreeNode node) {
if (node != null) {
System.out.print(node.getData() + " ");
prefix(node.getLeft());
prefix(node.getRight());
}
}

public void postfix() {
postfix(root);
System.out.println();
}

private void postfix(TreeNode node) {
if (node != null) {
postfix(node.getLeft());
postfix(node.getRight());
System.out.print(node.getData() + " ");
}
}

private boolean isOperator(String token) {
return token.equals("+") || token.equals("-") || token.equals("*") || token.equals("/");
}
}

//These codes are involved with the above code that needs fixing

NodeInterface.java (Don't edit)
interface NodeInterface<T>{
T getData();
NodeInterface<T> getLeft();
NodeInterface<T> getRight();
}
/**
*
* TreeNode.java: TreeNode class. // (Don't edit)
*/
public class TreeNode implements NodeInterface<String>
{
private String value;
private TreeNode left, right;

public TreeNode(String initValue)
{
value = initValue;
left = null;
right = null;
}

public TreeNode(String initValue, TreeNode initLeft, TreeNode initRight)
{
value = initValue;
left = initLeft;
right = initRight;
}

public String getData()
{
return value;
}

public TreeNode getLeft()
{
return left;
}

public TreeNode getRight()
{
return right;
}

public void setValue(String theNewValue)
{
value = theNewValue;
}

public void setLeft(TreeNode theNewLeft)
{
left = theNewLeft;
}

public void setRight(TreeNode theNewRight)
{
right = theNewRight;
}
}