second

src/Statement.java

+import org.university.core.Employee;
+
+public class Statement {
+    private double amount;
+    private Employee reciever;
+
+    public Statement(double amount, Employee reciever) {
+        this.amount = amount;
+        this.reciever = reciever;
+    }
+}

src/org/university/core/Course.java

@@ -6,14 +6,14 @@ public class Course {
     private String name;
     private Professor instructor;
     private ArrayList<Student> students = new ArrayList<Student>();
-    private GraduateStudent teacherAssistance;
+    private GradStudent teacherAssistance;
 
 
-    public GraduateStudent getTeacherAssistance() {
+    public GradStudent getTeacherAssistance() {
         return teacherAssistance;
     }
 
-    public void setTeacherAssistance(GraduateStudent teacherAssistance) {
+    public void setTeacherAssistance(GradStudent teacherAssistance) {
         this.teacherAssistance = teacherAssistance;
     }
 

src/org/university/core/Employee.java

 package org.university.core;
 
+import java.sql.Statement;
 import java.util.ArrayList;
 
 public class Employee extends Person {

src/org/university/core/Professor.java

@@ -21,5 +21,8 @@ public class Professor extends Employee{
     public void addCourse(Course c){
         courses.add(c);
     }
+    public double getCurrentIncome(){
+
+    }
 
 }