4th

src/org/university/core/Account.java

+package org.university.core;
+
+public class Account
+{
+    private AbstractEmployee owner;
+    private double credit;
+
+    public Account(AbstractEmployee owner, double credit) {
+        this.owner = owner;
+        this.credit = credit;
+    }
+
+    public AbstractEmployee getOwner() {
+        return owner;
+    }
+
+    public void setOwner(AbstractEmployee owner) {
+        this.owner = owner;
+    }
+
+    public double getCredit() {
+        return credit;
+    }
+
+    public void setCredit(double credit) {
+        this.credit = credit;
+    }
+}
\ No newline at end of file

src/org/university/core/AccountingManagement.java

+package org.university.core;
+
+import java.util.ArrayList;
+
+public class AccountingManagement {
+    private ArrayList<Account> accounts;
+    private ArrayList<Statement> statements;
+    public void checkout(AccountingInterface employee)
+    {
+        boolean command = true;
+        for (Account account:accounts)
+        {
+            if (account.getOwner()==employee)
+            {
+                double amount = employee.callCurrentIncome();
+                account.setCredit(account.getCredit()+amount);
+                command = false;
+                Statement s = new Statement(amount,employee.callEmployee());
+                statements.add(s);
+            }
+        }
+        if (command)
+        {
+            double amount = employee.callCurrentIncome();
+            Account ac = new Account(employee.callEmployee(),employee.callCurrentIncome());
+            accounts.add(ac);
+            Statement s = new Statement(amount,employee.callEmployee());
+            statements.add(s);
+        }
+
+    }
+}

src/org/university/core/GradStudent.java

@@ -3,18 +3,20 @@ package org.university.core;
 import java.util.ArrayList;
 
 public class GradStudent extends Student{
-    private ArrayList<publication>publications;
+    private ArrayList<Publication>publications;
     private Professor advisor;
     public GradStudent(String firstName, String lastName, String ID, int joiningYear, Department department,Professor professor) {
         super(firstName, lastName, ID, joiningYear, department);
-        publications=new ArrayList<publication>();
+        publications=new ArrayList<Publication>();
         this.advisor=professor;
     }
     public void addPublication(Publication p){
         publications.add(p);
     }
 
-    public ArrayList<publication> getPublications() {
+    public ArrayList<Publication> getPublications() {
         return publications;
     }
+
+//    public int calCurrentIncome(){}
 }