6th

src/org/university/core/AbstractEmployee.java

+package org.university.core;
+
+
+import java.util.ArrayList;
+
+public abstract class AbstractEmployee extends Person implements AccountingInterface{
+
+    protected ArrayList<Statement> bankStatments = new ArrayList<Statement>();
+    protected String position;
+    protected double basicIncome,currentIncome;
+
+    public AbstractEmployee(String firstName, String lastName, String ID, int joiningYear, Department department, String position, double basicIncome) {
+        super(firstName, lastName, ID, joiningYear, department);
+        this.position = position;
+        this.basicIncome = basicIncome;
+    }
+
+    public abstract boolean isPromotable();
+
+    public void addBankStatement(Statement s) { bankStatments.add(s); }
+
+    @Override
+    public AbstractEmployee callEmployee() {
+        return this;
+    }
+
+    @Override
+    public double callCurrentIncome() {
+        return callCurrentIncome();
+    }
+
+    public ArrayList<Statement> getBankStatments() {
+        return bankStatments;
+    }
+
+    public String getPosition() {
+        return position;
+    }
+
+    public void setPosition(String position) { this.position = position; }
+
+    public double getBasicIncome() {
+        return basicIncome;
+    }
+
+    public void setBasicIncome(double basicIncome) { this.basicIncome = basicIncome; }
+
+    public void setCurrentIncome(double currentIncome) { this.currentIncome = currentIncome; }
+
+    public double calCurrentIncome()
+    {
+        return currentIncome;
+    }
+}

src/org/university/core/AccountingInterface.java

+package org.university.core;
+
+public interface AccountingInterface {
+    public AbstractEmployee callEmployee();
+    public double callCurrentIncome();
+}

src/org/university/core/Statement.java

+package org.university.core;
+
+public class Statement {
+    private double amount;
+    private AbstractEmployee reciever;
+
+    public Statement(double amount, AbstractEmployee reciever) {
+        this.amount = amount;
+        this.reciever = reciever;
+    }
+    public double getAmount() {
+        return amount;
+    }
+
+    public void setAmount(double amount) {
+        this.amount = amount;
+    }
+
+    public AbstractEmployee getReciever() {
+        return reciever;
+    }
+
+    public void setReciever(AbstractEmployee reciver) {
+        this.reciever = reciever;
+    }
+}