Reference data types in Java - Mini Project: Build & Apply

Understanding Reference Data Types in Java

📖 Scenario: You are creating a simple program to store and display information about a book. This will help you understand how reference data types work in Java.

🎯 Goal: Build a Java program that creates a Book object with a title and author, then prints the book details.

📋 What You'll Learn

Create a class called Book with two String fields: title and author.

Create an instance of Book with specific title and author values.

Use a variable to hold the Book object reference.

Print the book's title and author using the object reference.

💡 Why This Matters

🌍 Real World

Reference data types like objects are used to model real-world things in programs, such as books, people, or products.

💼 Career

Understanding how to create and use objects is fundamental for Java programming jobs, especially in software development and application design.

1

Create the Book class with fields

Write a class called Book with two public String fields named title and author. Do not add any methods yet.

Java

public class Book {
    // Your code here
}

Need a hint?

Use public String title; and public String author; inside the class.

2

Create a Book object with title and author

In the Main class, create a variable called myBook of type Book. Then create a new Book object and assign it to myBook. Set myBook.title to "The Java Journey" and myBook.author to "Alex Reader".

Java

public class Book {
    public String title;
    public String author;
}

public class Main {
    public static void main(String[] args) {
        // Create a Book object called myBook
        // Your code here
    }
}

Need a hint?

Use Book myBook = new Book(); to create the object, then set fields with myBook.title = ....

3

Use the myBook reference to access fields

Add a String variable called bookInfo that combines myBook.title and myBook.author in this format: "Title: The Java Journey, Author: Alex Reader".

Java

public class Book {
    public String title;
    public String author;
}

public class Main {
    public static void main(String[] args) {
        Book myBook = new Book();
        myBook.title = "The Java Journey";
        myBook.author = "Alex Reader";
        
        // Create bookInfo string combining title and author
        // Your code here
    }
}

Need a hint?

Use string concatenation with +"Title: " + myBook.title + ", Author: " + myBook.author.

4

Print the book information

Use System.out.println to print the bookInfo variable.

Java

public class Book {
    public String title;
    public String author;
}

public class Main {
    public static void main(String[] args) {
        Book myBook = new Book();
        myBook.title = "The Java Journey";
        myBook.author = "Alex Reader";
        
        String bookInfo = "Title: " + myBook.title + ", Author: " + myBook.author;
        // Print bookInfo
        // Your code here
    }
}

Need a hint?

Use System.out.println(bookInfo); to display the text.