Noob really needs help please with beginner Assignment

[Paul Di]

Hello everyone,

Sorry if it seems like I need to be spoon fed because that how I feel. I am usually a quick learner but that does not seem to be the case with java. I am learning C# and feel like I am catching on quickly but I feel very frustrated that I can not even complete my java first assignment.

I have been reading as much as possible and watching the tutorials, I plan to continue to do both.

I am hopeful someone would be kind enough to point me in the right direction so I can complete my assignment. Any help at all would be very much appreciated.

Here is the assignment I need to complete

Assignment 1 is to practice creating classes, attributes, methods, and basic syntax and flow control. There are two parts in this assignment.

Part 1

You will create two classes, Employee and EmployeeTable. Employee represents an employee record in a table of employee records. It will have three attributes: employee number, employee name and salary. Employee class also has methods that allow other objects to change its attributes or print out all its attributes.

EmployeeTable represents a table of employee records with a company. This class has two attributes: the name of company and the actual table that contains all the employee records. The latter can be implemented using a Java library class Hashtable.

The class EmployeeTable will have behavior/methods that allow other objects to call to do the following:

Get the total number of employees in the table
Insert an employee in the table, the employee object being passed to the method
Delete an employee from the table, the employee number being passed to the method
Update an employee in the table, the employee number being passed to the method

Part 2

You will create a test class that instantiates a new EmployeeTable and then loops infinitely to take some user input from console and then allows user to invoke one of the methods of the EmployeeTable to insert, delete or update an employee record in the table. The test program will exit if user enters Q on the console.

Some example output is as follows:

EmpClient.main(): client started...

[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: a
Adding a new employee...
Enter a string value for empNo: emp-01
Enter a string value for empName: George Bush
Enter a float value for salary: 80000
Employee added:
emp-01, George Bush, 80000.0

[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: a
Adding a new employee...
Enter a string value for empNo: emp-02
Enter a string value for empName: Greg Harper
Enter a float value for salary: 50000
Employee added:
emp-02, Greg Harper, 50000.0

[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: a
Adding a new employee...
Enter a string value for empNo: emp-03
Enter a string value for empName: Brad Linsley
Enter a float value for salary: 45000
Employee added:
emp-03, Brad Linsley, 45000.0

[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: l
Listing all employees...
3 employees found:
emp-03, Brad Linsley, 45000.0
emp-02, Greg Harper, 50000.0
emp-01, George Bush, 80000.0

[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: e
Editing an employee...
Enter a string value for empNo: emp02
No record exists for emp02

[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: e
Editing an employee...
Enter a string value for empNo: emp-02
Enter a new string value for empName: Brad Linsle
Enter a new float value for salary: 55000
Employee updated:
emp-02, Brad Linsley, 55000.0

[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: d
Deleting an employee...
Enter a string value for empNo: emp-01
Employee deleted:
emp-01, George Bush, 80000.0

[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: l
Listing all employees...
2 employees found:
emp-03, Brad Linsley, 45000.0
emp-02, Brad Linsley, 55000.0

[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: q
EmpClient.main(): client exiting...
Done.

Question about part 1,

It will have three attributes: employee number, employee name and salary. Employee class also has methods that allow other objects to change its attributes or print out all its attributes.

Is it as simple at this?
private String empName;
private int empNo;
private double empSalary;

I am having an issue getting the employee Class started.

template for EmployeeTable. I have started the update method. I don't really understand what is being passed in to the method to be honest.

package paul;

import java.util.*;

public class EmployeeTable {
	//The member variable that will hold employees
	//Make the empNo the key, and the employee object the value
	//for each record
  private Hashtable table;

  //Constants that the add(), update(), and delete() methods will
  //return to show the various the results of the operations
  public  static  int INVALIDINPUT=0, DUPLICATEKEYERROR=1, ADDED=2,
  	DELETED=3, UPDATED=4, RECORDNOTFOUNDERROR=5;

  public EmployeeTable() {
  		table=new Hashtable();
  }

//Implement the following member methods:

//Add a record to this table
//If row is null or empty, return INVALIDINPUT
//If there already exists a record in the table with the same empNo
//as the one passed to this method, return DUPLICATEKEYERROR,
//otherwise, add it and return ADDED
  public int add(EmployeeRow row)
  {
	  //...
  }


//Update a record in the table
//If row is null or empty, return INVALIDINPUT
//If there does not exist a record in the table with the same empNo
//as the one passed to this method, return RECORDNOTFOUNDERROR,
//otherwise, update the record and return UPDATED
  public int update(EmployeeRow row)
  {
	public int add(EmployeeRow row)
{
if(row==null)
	return INVALIDINPUT;
else 
{
	String key = row.getEmpNo();
	Object obj = table.get(key);
	if(obj!=null)
		return DUPLICATEKEYERROR;

	else
		table.put(row.getEmpNo(), row);
		return ADDED;

}
  }

//Delete a record in the table
//If key is null or empty, return INVALIDINPUT
//If there does not exist a record in the table with the same empNo
//as the key passed to this method, return RECORDNOTFOUNDERROR,
//otherwise, delete the record and return DELETED
  public int delete(String key)
  {
	  //...
  }


//Get a row with the given key
//If this key does not exist in the table return null,
//otherwise return its corresponding value
  public EmployeeRow getRow(String key)
  {

Part 2: Test class started (some of this was provided in a template and I realize the is code that needs to be added in the switch statement. Case L needs System.out.println(table.toString()); etc.

package paul;

import java.io.IOException;
import java.util.Scanner;

public class Test {

    static Scanner keyboard = new Scanner(System.in);
    
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		while (true) {
			String action = getInput("[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: ");
			if (action.length() == 0 || action.toUpperCase().charAt(0) == 'Q') {
				System.out.println("EmpClient.main(): client exited");
				break;
			}
			switch (action.toUpperCase().charAt(0)) {
				case 'L':
					System.out.println("Listing all employees...");
					break;
				case 'A':
					System.out.println("Adding an employee...");
					break;
				case 'E':
					System.out.println("Updating an employee...");
					break;
				case 'D':
					System.out.println("Deleting an employee...");
					break;
				default:
					System.out.println("Invalid command. Try again.\n");
			}//end switch
		}//end while		
			
	}

	/**
	 * After printing a prompt, reads a line of text.
	 */
	private static String getInput(String prompt) {
		System.out.print(prompt);
		System.out.flush();
		
		String input = keyboard.nextLine();
		
		return input;
	}
	
	
}

If anyone could help me out, I would greatly appreciate it. In the mean time I will continue to read until my eyes bleed. Thank you for your time.

[Winston Gutkowski]

Paul Di wrote:Question about part 1,

It will have three attributes: employee number, employee name and salary. Employee class also has methods that allow other objects to change its attributes or print out all its attributes.

Is it as simple at this?
private String empName;
private int empNo;
private double empSalary;

Yup. And well done for avoiding the "beginners 101" mistake of making everything a String.

I am having an issue getting the employee Class started...

The above looks pretty good to me. Do that; get your constructors sorted out; add any getters and setters you think you might need (Tip: be especially careful about adding setters if you don't need them - my technique: don't add them until you need them); and then get started on the "beef" (ie, the methods that actually do something).

I hate to say, but that's too much code to go through. Get your class started and come back with a specific question when/if you have problems.

Another good tip from one of my colleagues here: Don't write more than 10 lines of code without compiling it.

HIH

Winston

[Paul Di]

So I am slowly making some progress but I am having some issues. I am trying to pass an object as the value to the hash table, however when I hit "L" for list and try to print out the hash table I only see what ever value is entered for "please enter employee ID number". Just wondering if you could give me an idea what I am doing wrong. I know there is other methods still to fill out but for now I am just working on adding employees to the hash table and printing out a list of the employees that have been added to the hash table.

test class

package paul;
 
import java.io.IOException;
import java.util.Scanner;
 
public class Test {
 
        static Scanner keyboard = new Scanner(System.in);
        static Scanner keyboard2 = new Scanner(System.in);
        
        public static void main(String[] args) {
 
                EmployeeTable obj = new EmployeeTable();
                // TODO Auto-generated method stub
                while (true) {
                        String action = getInput("[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: ");
                        if (action.length() == 0 ||action.toUpperCase().charAt(0) == 'Q') {
                                System.out.println("EmpClient.main(): client exited");
                                break;
                        }
 
                        switch (action.toUpperCase().charAt(0)) {
                        case 'L':
                        {System.out.println("Listing all employees...");
                        obj.list();
                        break;}
                        case 'A':
                                System.out.println("Please enter Employee Name");
                                String name = keyboard.nextLine();
 
                                System.out.println("Please enter Employee Id Number");
                                String number = keyboard.nextLine();
 
                                System.out.println("Please enter salary");
                                double sal= keyboard2.nextDouble();
 
                                Employee row = new Employee (name, number, sal);
                                obj.add(row);
                                System.out.println("Adding an employee...");
                                break;
                        case 'E':
                                System.out.println("Updating an employee...");
                                break;
                        case 'D':
                                System.out.println("Deleting an employee...");
                                break;
                        default:
                                System.out.println("Invalid command. Try again.\n");
                        }//end switch
                }//end while      
        }
 
        /**
         * After printing a prompt, reads a line of text.
         */
        private static String getInput(String prompt) {
                System.out.print(prompt);
                System.out.flush();
 
                String input = keyboard.nextLine();
 
                return input;
        }
 
}

EmployeeTable class

package paul;
 
import java.util.*;
 
public class EmployeeTable {
        // The member variable that will hold employees
        // Make the empNo the key, and the employee object the value
        // for each record
        public Hashtable <String, Object> table;
 
        // Constants that the add(), update(), and delete() methods will
        // return to show the various the results of the operations
        public static int INVALIDINPUT = 0, DUPLICATEKEYERROR = 1, ADDED = 2,
                        DELETED = 3, UPDATED = 4, RECORDNOTFOUNDERROR = 5;
 
        public EmployeeTable() {
                table  = new Hashtable <String, Object> ();
        }
 
        // Implement the following member methods:
 
        // Add a record to this table
        // If row is null or empty, return INVALIDINPUT
        // If there already exists a record in the table with the same empNo
        // as the one passed to this method, return DUPLICATEKEYERROR,
        // otherwise, add it and return ADDED
        public int add(Employee row) {
            if (row == null)
                    return INVALIDINPUT;
            else {
                    String key = row.getEmpNo();
                    Object obj = table.get(key);
                    if (obj != null)
                            return DUPLICATEKEYERROR;
 
                    else
                            table.put(row.getEmpNo(), row);
                    
                    return ADDED;
            }
    }
 
        // Update a record in the table
        // If row is null or empty, return INVALIDINPUT
        // If there does not exist a record in the table with the same empNo
        // as the one passed to this method, return RECORDNOTFOUNDERROR,
        // otherwise, update the record and return UPDATED
              
        public int update(Employee row) {
                return 0;
        }
 
         
        // Delete a record in the table
        // If key is null or empty, return INVALIDINPUT
        // If there does not exist a record in the table with the same empNo
        // as the key passed to this method, return RECORDNOTFOUNDERROR,
        // otherwise, delete the record and return DELETED
        public int delete(Employee row) {
                // ...
                return 0;
        }
 
        // Get a row with the given key
        // If this key does not exist in the table return null,
        // otherwise return its corresponding value
        public Employee getRow(Employee row) {
                return null;
        }
                
        public void list(){
       
                for (String itm : table.keySet())
 
                {  
                        System.out.println(itm + " " + table.get(itm));
 
                }
                
        }
      
}

Employee Class

package paul;
 
public class Employee{
    /**
     * @return the empName
     */
    public String getEmpName() {
            return empName;
    }
 
    /**
     * @param empName the empName to set
     */
    public void setEmpName(String empName) {
            this.empName = empName;
    }
 
    /**
     * @return the empNo
     */
    public String getEmpNo() {
            return empNo;
    }
 
    /**
     * @param empNo the empNo to set
     */
    public void setEmpNo(String empNo) {
            this.empNo = empNo;
    }
 
    /**
     * @return the empSalary
     */
    public double getEmpSalary() {
            return empSalary;
    }
 
    /**
     * @param empSalary the empSalary to set
     */
    public void setEmpSalary(double empSalary) {
            this.empSalary = empSalary;
    }
 
    private String empName;
    private String empNo;
    private double empSalary;
   
    public Employee(String name, String number, double pay){
            this.empName = name;
            this.empNo = number;
            this.empSalary = pay;
    }
}

Sample of the output[L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: a Please enter Employee Name name1 Please enter Employee Id Number id1 Please enter salary 100 Adding an employee... [L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: a Please enter Employee Name name2 Please enter Employee Id Number id2 Please enter salary 200 Adding an employee... [L]ist| [A]dd | [E]dit | [D]elete | [Q]uit: l Listing all employees... id2 paul.Employee@86c347 id1 paul.Employee@17e6a96 [L]ist| [A]dd | [E]dit | [D]elete | [Q]uit:

[Paul Di]

Well I did get the issue solved. It was just a matter of needing to override the toString() method in the Employee class.