Creating a Simple Class and Testing It in JAVA

Goal

Create a class called Book that represents a book in a library. The Book class should have attributes, constructors, and methods that help manage book information. Then, write a small program to create Book objects and test the class.

Steps to Complete the Assignment

Step $1$: Define a Simple Class

Create a new file called Book.java.

Define a class named Book.

Add the following private data members to the class:

String title

String author

int pages

double price

Step $2$: Create Constructors

Inside the Book class, create two constructors:

A default constructor that initializes title, author to empty strings, and pages, price to $0.$

A parameterized constructor that takes title, author, pages, and price as parameters and initializes the class variables accordingly.

Step $3$: Add Methods to the Class

Create public methods for the class:

public void displayBookInfo$()$: Prints the book's title, author, pages, and price.

public void updatePrice$($double newPrice$)$: Updates the price of the book to the value provided by newPrice.

Step $4$: Create a Test Class

Create another file called Main.java.

In Main.java, include the necessary imports $($import java.util.$*$; if needed$).$

Write the main$()$ function that performs the following:

Create a default Book object using the default constructor and call displayBookInfo$()$ to show initial values.

Create another Book object using the parameterized constructor and call displayBookInfo$().$

Use the updatePrice$()$ method to update the price of the book and display the updated information using displayBookInfo$().$

Step $5$: Compile and Test

Compile both Book.java and Main.java.

Run the program and ensure the following works:

Both constructors properly initialize objects.

The displayBookInfo$()$ method displays the correct book information.

The updatePrice$()$ method correctly updates the price.

Sample Output

When you run the program, you should see output similar to the following:

Default Book Info:

Title:$$

Author:$$

Pages: $0$

Price: $0\mathrm{.}0$

Book Info:

Title: The Great Gatsby

Author: F$.$ Scott Fitzgerald

Pages: $180$

Price: $10\mathrm{.}99$

Updated Book Price:

Title: The Great Gatsby

Author: F$.$ Scott Fitzgerald

Pages: $180$

Price: $12\mathrm{.}99$