Index: ActiviteitenOpvolging/ActiviteitenOpvolging/domain/managers/implementations/EmployeeManager.vb
===================================================================
diff -u -r1714 -r1718
--- ActiviteitenOpvolging/ActiviteitenOpvolging/domain/managers/implementations/EmployeeManager.vb	(.../EmployeeManager.vb)	(revision 1714)
+++ ActiviteitenOpvolging/ActiviteitenOpvolging/domain/managers/implementations/EmployeeManager.vb	(.../EmployeeManager.vb)	(revision 1718)
@@ -1,4 +1,6 @@
-Public Class EmployeeManager
+Imports ActiviteitenOpvolging.configs
+
+Public Class EmployeeManager
     Implements IEmployeeManager
 
     Private ReadOnly _employees As ICollection(Of IEmployee)
@@ -15,44 +17,70 @@
             'Select the employees from the collection of all employees, which are not selected yet.
             'The employees are compared on their initials in lowercase.
             Return New HashSet(Of IEmployee)(_employees.Where(Function(employee) _
-                                                                 Not _selectedEmployees.Any(Function(selectedEmployee) _
+                                                                 Not _selectedEmployeesDictionary.Any(Function(selectedEmployee) _
                                                                                                employee.Equals(selectedEmployee))))
         End Get
     End Property
 
-    Private ReadOnly _selectedEmployees As New List(Of IEmployee)
+    Private ReadOnly _selectedEmployeesDictionary As new Dictionary(Of Integer, IEmployee)
     ''' <inheritdoc/>
     Public ReadOnly Property SelectedEmployees As ICollection(Of IEmployee) Implements IEmployeeManager.SelectedEmployees
         Get
-            Return New HashSet(Of IEmployee)(_selectedEmployees)
+            Return New HashSet(Of IEmployee)(_selectedEmployeesDictionary.Values)
         End Get
     End Property
 
     Sub New()
         'Initial fetching of employees, then stored.
         _employees = EmployeesDatabaseMapper.FetchEmployees()
+        'Filling the selected employees dictionary with the employee number (an index) and 'Nothing' as value. Indicating no selected employee.
+        For i = 0 To ConfigsLoader.NumberOfEmployees - 1
+            _selectedEmployeesDictionary.Add(i, Nothing)
+        Next
     End Sub
 
     ''' <inheritdoc/>
-    Public Sub SelectEmployee(employee As IEmployee) Implements IEmployeeManager.SelectEmployee
-        'Check whether or not that employee is already picked.
-        If _selectedEmployees.Any(Function(selectedEmployee) selectedEmployee.Equals(employee)) Then
+    Public Function GetSelectedEmployee(employeeNumber As Integer) As IEmployee Implements IEmployeeManager.GetSelectedEmployee
+        If _selectedEmployeesDictionary.ContainsKey(employeeNumber) Then
+            Throw New InternalException($"Employee number for getting the selected value is invalid, key value: {employeeNumber}.")
+        End If
+        'Get the value.
+        Return _selectedEmployeesDictionary.Item(employeeNumber)
+    End Function
+
+    ''' <inheritdoc/>
+    Public Sub SelectEmployee(employeeNumber As Integer, employee As IEmployee) Implements IEmployeeManager.SelectEmployee
+        'Employee number must be valid: exist in the dictionary.
+        If not _selectedEmployeesDictionary.ContainsKey(employeeNumber) Then
+            Throw New InternalException($"Employee number for selecting an employee is invalid, key value: {employeeNumber}.")
+        End If
+        'Employee can't be nothing.
+        If employee Is Nothing Then
+            Throw New InternalException($"The soon-to-be selected Employee can't be nothing.")
+        End If
+        'Check whether or not that employee is already picked. The selected employees can be 'Nothing'.
+        If _selectedEmployeesDictionary.Values.Any(Function(selectedEmployee) Not IsNothing(selectedEmployee) AndAlso selectedEmployee.Equals(employee)) Then
             'Employee was picked already.
             Throw New Exception("Employee was already chosen.")
         End If
-        'Add employee to list of selected employees.
-        _selectedEmployees.Add(employee)
+        'No employee can already be selected for that number.
+        If _selectedEmployeesDictionary.Item(employeeNumber) IsNot Nothing Then
+            Throw New Exception($"An employee was already chosen for number (index): {employeeNumber}.")
+        End If
+
+        'Add employee to dictionary of selected employees -> set the value according to an employee number.
+        _selectedEmployeesDictionary.Item(employeeNumber) = employee
     End Sub
 
     ''' <inheritdoc/>
-    Public Sub RemoveEmployeeSelection(employee As IEmployee) Implements IEmployeeManager.RemoveEmployeeSelection
+    Public Sub RemoveEmployeeSelection(employeeNumber As Integer) Implements IEmployeeManager.RemoveEmployeeSelection
         'Find the employee to remove.
-        Dim employeeToRemove = _selectedEmployees.Find(Function(selectedEmployee) selectedEmployee.Equals(employee))
+        Dim employeeToRemove = _selectedEmployeesDictionary.Item(employeeNumber)
         If employeeToRemove Is Nothing Then
             'The employee was not selected, thus can't be deselected.
             Throw New Exception("Cannot remove the selection of a non-selected employee.")
         End If
-        'Remove the employee.
-        _selectedEmployees.Remove(employeeToRemove)
+        'Remove the employee -> set the value back to 'Nothing'.
+        _selectedEmployeesDictionary.Item(employeeNumber) = Nothing
     End Sub
 End Class