Section $1$: Classes and Objects $(15$ points$)$

$1\mathrm{.}1$ Define a class named $`$Rectangle$`$ with attributes $`$length$`$ and $`$width$`.$ Include a method named $$calculate Area$$ that returns the area of the rectangle.

$1\mathrm{.}2$ Create an object of the $$Rectangle$$ class in the main method, set its length and width, and display the calculated area.

$1\mathrm{.}3$ Explain the concept of encapsulation and how it is implemented in Java.

Section $2$: Inheritance and Polymorphism $(20$ points$)$

$2\mathrm{.}1$ Create a base class $`$Vehicle$`$ with attributes $`$brand$`$ and $`$year$`.$ Include a method $$start Engine$$ that prints "Engine started."

$2\mathrm{.}2$ Derive a subclass $$Car$$ from $$Vehicle$$ with an additional attribute $`$NumDoors$`.$ Override the $$startEngine$$ method to print "Car engine started."

$2\mathrm{.}3$ In the main method, create objects of both $$Vehicle$$ and $$Car$$ classes. Demonstrate polymorphism by calling the $$startEngine$$ method on both objects.

Section $3$: Exceptions $(15$ points$)$

$3\mathrm{.}1$ Write a Java program that divides two numbers. Handle the $$ArithmeticException$$ to display a custom error message if division by zero occurs.

$3\mathrm{.}2$ Explain the purpose of the $$try$,$catch$,$ and $$finally$$ blocks in exception handling.

$3\mathrm{.}3$ Write a code snippet demonstrating the use of the $$throws$$ keyword in a method declaration.

Section $4$: Swing GUI $(20$ points$)$

$4\mathrm{.}1$ Create a simple Swing GUI application with a JFrame containing a JButton. When the button is clicked, display a JOptionPane with a message.

$4\mathrm{.}2$ Explain the role of the Event Dispatch Thread $($EDT$)$ in Swing applications and why it's important.

$4\mathrm{.}3$ Implement a JTextField and a JLabel in your Swing application. Update the label text dynamically based on the input in the text field.

Section $5$: Comprehensive Program $(10$ points$)$

Write a Java program that incorporates the concepts of classes, objects, inheritance, polymorphism, exceptions, and Swing GUI. The program should include at least one custom exception, a class hierarchy, and a graphical user interface.