"Duplicate" entries in ArrayList?

Question

i have this class thats going to fill a list with All employees that are pre made in an array. I can populate an ArrayList with employees but the only problem is that i get a few "Duplicate" entries, i use quotes cause they are not EXACTLY the same but they could share the same name or employee number but may not have the same hire year or salary ect.

heres the employee class :

public class Employee {

public String EmployeeName;
public String EmployeeNumber;
public int hireyear;
public double WeeklyEarning;

public Employee()
{
    EmployeeName = null;
    EmployeeNumber = null;
    hireyear = 0;
    WeeklyEarning = 0;

}

public static final String[] Empnum = new String[] {
        "0001-A", "0002-B","0003-C","0004-D","0002-A",
        "0003-B","0004-C","0005-D","0011-A", "0012-B",
        "0013-C","0014-D","0121-A", "0122-B","0123-C",
        "0321-A", "0312-B","1234-D","4321-C","1122-D"};

public static final String[] Ename = new String[] {
        "Josh", "Alex", "Paul", "Jimmy", "Josh", "Gordan", "Neil", "Bob",
        "Shiv", "James", "Jay", "Chris", "Michael", "Andrew", "Stuart",
        "Dave","Benjamin","Dan","Brian","Michelle"};

public String getEmployeeName()
{
    return this.EmployeeName;
}

public String getEmployeeNumber()
{
    return this.EmployeeNumber;
}

public int gethireyear()
{
    return this.hireyear;
}

public double getWeeklyEarning()
{
    return this.WeeklyEarning;
}

public String setEmployeeName(String EName)
{
    return this.EmployeeName = EName;
}

public String setEmployeeNumber(String ENumber)
{
    return this.EmployeeNumber = ENumber;
}

public int setEmployeehireyear(int Ehireyear)
{
    return this.hireyear = Ehireyear;
}

public double setEmployeeweeklyearning(double Eweeklyearning)
{
    return this.WeeklyEarning = Eweeklyearning;
}

public String toString(){
    String data = "\n Employee Name : " + EmployeeName + " \n Employee Number: " + EmployeeNumber + " \n Hire Year : " + hireyear + "\n Weekly Earnings : " + WeeklyEarning;
    return data;
}

public boolean equals(Object o){
    if(this == null){
        return false;
    }
    if(this == o){
        return true;
    }
    if(!(o instanceof Employee)){
        return false;
    }

    Employee temp = (Employee) o;
    if(this.getEmployeeName().equals(temp.getEmployeeName())){
        return true;

    }
    if(this.getEmployeeNumber().equals(temp.getEmployeeNumber())){
        return true;

    }
    if(this.gethireyear() == temp.gethireyear()){
        return true;
    }
    if(this.getWeeklyEarning() == temp.getWeeklyEarning()){
        return true;
    }
    return false;

}

}

Heres the generateList method that will populate the list:

public ArrayList<Employee> generateEmpList(){
    empList = new ArrayList <Employee>();
    Random empPicker = new Random();

    for(int i = 0; i < 20; i++){
        int id = empPicker.nextInt(20);
        if(id < 12) // roll for production worker
        {

            //System.out.println("Adding Production Worker");
            ProductionWorker temp = new ProductionWorker();
            temp = temp.generateProductionWorker();
            prodWorker = temp;
            empList.add(prodWorker);

        }
        else //roll for Shift supervisor
        {
            //System.out.println("Adding Shift supervisor");
            ShiftSupervisor supervisor = new ShiftSupervisor();
            supervisor = supervisor.generateShiftSupervisor();
            shiftWorker = supervisor;
            empList.add(shiftWorker);
        }
    }
    Iterator iterator = empList.iterator();
    while (iterator.hasNext()) {
        System.out.println("");
        System.out.println(iterator.next());

    }
    return empList;
}

and also which could be helpful is the "generateProductionWorker()" and shiftSupervisor methods - to keep it short ill only post prod worker method cause they are basically the same:

public ProductionWorker generateProductionWorker(){
    Random rng = new Random();
    int numberOfEmployeeNames = Ename.length;
    ProductionWorker tempPworker = new ProductionWorker();

    String employeeName = Ename[rng.nextInt(numberOfEmployeeNames)];
    tempPworker.setEmployeeName(employeeName);

    int numberOfEmployeeNumbers = Empnum.length;
    String employeeNumber = Empnum[rng.nextInt(numberOfEmployeeNumbers)];
    tempPworker.setEmployeeNumber(employeeNumber);

    int yearHired = rng.nextInt(35) + 1980;
    tempPworker.setEmployeehireyear(yearHired);

    double weeklySalary = rng.nextInt((100) * 100);
    tempPworker.setEmployeeweeklyearning(weeklySalary);

    int hourlyRate = rng.nextInt(20) + 10;
    tempPworker.setHourlyRate(hourlyRate);

    return tempPworker;

}

I'm sure I'm missing something trivial but any ideas why i get similar entries when i have a list of 20 names and numbers?

ex: empname - josh empnum - 0000-A hireyear - 1994 salary - 40,000

empname - josh empnum - 0000-A hireyear - 1999 salary - 60,500

any advice would help, Thanks!

Answer 1

I agree with Georgi, you equals method is the culprit.

Currently it is returning true after the first if statement at the line that reads

if(this.getEmployeeName().equals(temp.getEmployeeName())){
    return true;
}

Because it is a return statement it stops the method from continuing to the other statements. You might try this:

    public boolean equals(Object o){
        if(this == null){
            return false;
        }
        if(this == o){
            return true;
        }
        if(!(o instanceof Employee)){
           return false;
        }
        //set all the elements in the array to false and change to true when true.
        boolean [] doesItMatch = new boolean[4];
        doesItMatch[0] = false;
        doesItMatch[1] = false;
        doesItMatch[2] = false;
        doesItMatch[3] = false;

        Employee temp = (Employee) o;
        if(this.getEmployeeName().equals(temp.getEmployeeName())){
            doesItMatch[0] = true;
        }
        if(this.getEmployeeNumber().equals(temp.getEmployeeNumber())){
            doesItMatch[1] = true;
        }
        if(this.gethireyear() == temp.gethireyear()){
            doesItMatch[2] = true;
        }
        if(this.getWeeklyEarning() == temp.getWeeklyEarning()){
            doesItMatch[3] = true;
        }
        int check = 0;
        //Now that you have checked all the values, check the array. Using a simple counter. 
        for(int i = 0; i < doesItMatch.length; i++){
            if(doesItMatch[i]){
                check++;
            } else {
                check--;
            }
        }
        //The counter should be 4 when the if statements above are all true. Anything else is false.
        if(check == 4){
            return true;
        } else {
            return false;
        }
    }

This method now checks each of the attributes in the Employee class. (Name, Number, Hire year and so on. If you create more attributes to the class it is easy to add more elements to the array just be sure to set them to false.) Hope this helps This also would take a little maintenance if you expanded the Employee class so you might want to find a way to make it a little easier on yourself.

Answer 2

Look at the equals method in your Employee class. If their name are the same, you return true, which means these are equals. The same is for the other attributes. You must replace your if statements.