How to compare each nodes in BST to return the highest element

[bezzel.zubber]

I want to compare between nodes in BST to find the highest salary and im using recursion function in implementing my BST.

Below is the question:

A company needs to keep all records of its employees. Employee record should
contain employee id(4 digit integer numbers), name, department, salary and
an employee phone number. Using bst, write a program to do the following tasks:

1. Insert data. (Arrange by employee id).
2. Display all data.
3. Display data of all employees from the same department.
4. Display the employee with the highest salary.
5. Count and display how many employee have salary > 10000
6. Display the total salary of all employees.
7. Display the average salary.

*no data duplication

So this is my code for finding the highest salary. It doesn't give the correct output.

  public void highestSalary()
  {     
    System.out.println("\n<EMPLOYEE WITH HIGHEST SALARY>\n");
    Employee highestEmployee = new Employee();
    Employee highestEmp = highestSalaryHelper(root, 0.0, highestEmployee);
    System.out.println(highestEmp.toString());

  }

  public Employee highestSalaryHelper(TreeNode node, double hS, Employee hE)
  {     


    if(node.left!=null)
    {
        if(node.data.getSalary()>hS)
        {
            hS = node.data.getSalary();
            hE = node.data;
        }

        else
        {
            highestSalaryHelper(node.left, node.left.data.getSalary(), hE);
        }
    }

    if(node.right!=null)
    {
        if(node.data.getSalary()>hS)
        {
            hS = node.data.getSalary();
            hE = node.data;
        }

        else
        {
            highestSalaryHelper(node.right, node.right.data.getSalary(), hE);
        }
    }   


    return node.data;   


  }

}

[bezzel.zubber]

no one able to solve this? or didnt get what im asking about?

[bguild]

Why do you modify hS and hE even when those variables will never be used again?

Why do you call highestSalaryHelper and not use its return value? Isn't its return value supposed to be an employee with the the highest salary? I thought you wanted that employee.

Why does highestSalaryHelper have only one return statement that always returns the employee of the node that highestSalaryHelper was given? What if that's not the employee with the highest salary?

[bezzel.zubber]

Im using hS and hE to assign highest salary and the employee with the highest salary so that it can compare salary from every node in the bst and return the employee.

Why im calling highestSalary though didn't use the return value? I did use its value to display the employee data.

I didn't actually really know how to traverse through all nodes in the bst and sorry if my code looks so rubbish, im still a beginner.

[bguild]

In your highestSalaryHelper you want three Employees. One of them is node.data. One of them is the highest salary employee from node.left and the the last one is the highest salary employee from node.right. Once you have those three, I hope you can figure out the highest salary employee of the entire tree.

I recommend that you simplify your problem by making highestSalaryHelper take only one argument, a TreeNode node, and promise yourself that highestSalaryHelper will always return the Employee with the highest salary among the employees in node and its children. Then you can get your three Employees easily as node.data, highestSalaryHelper(node.left), and hightestSalaryHelper(node.right). Of course you'll have to check for nulls.