Heap memory in Java - Mini Project: Build & Apply

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Understanding Heap Memory in Java

📖 Scenario: Imagine you are managing a small library system where you keep track of books. Each book has a title and an author. You want to understand how Java stores objects like books in heap memory.

🎯 Goal: You will create a simple Java program that creates book objects stored in heap memory, then display their details. This will help you see how objects live in heap memory and how references work.

📋 What You'll Learn

Create a Book class with title and author fields

Create two Book objects with exact titles and authors

Store the Book objects in variables

Print the details of each Book object

💡 Why This Matters

🌍 Real World

Understanding heap memory helps you manage objects in Java programs, like managing books in a library system or users in an app.

💼 Career

Knowing how objects are stored and accessed in heap memory is essential for Java developers to write efficient and bug-free code.

1

Create the Book class

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

Java

// Your code here

💡 Need a hint?

Use public class Book {} and inside it declare public String title; and public String author;.

2

Create two Book objects

In the main method of a Library class, create two Book objects named book1 and book2. Set book1.title to "Java Basics" and book1.author to "Alice". Set book2.title to "Data Structures" and book2.author to "Bob". Use the new keyword to create the objects.

Java

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

public class Library {
    public static void main(String[] args) {
        // Create book1 and book2 objects with titles and authors
        // Your code here
    }
}

💡 Need a hint?

Use Book book1 = new Book(); then set fields with book1.title = "Java Basics"; and book1.author = "Alice";. Repeat for book2.

3

Add a method to print book details

Add a public method called printDetails inside the Book class. This method should print the book's title and author in the format: Title: [title], Author: [author].

Java

public class Book {
    public String title;
    public String author;
    // Add printDetails method here
    // Your code here
}

public class Library {
    public static void main(String[] args) {
        Book book1 = new Book();
        book1.title = "Java Basics";
        book1.author = "Alice";

        Book book2 = new Book();
        book2.title = "Data Structures";
        book2.author = "Bob";
    }
}

💡 Need a hint?

Define public void printDetails() and inside use System.out.println to show title and author.

4

Print details of both books

In the main method of Library, call the printDetails method on both book1 and book2 to display their information.

Java

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

    public void printDetails() {
        System.out.println("Title: " + title + ", Author: " + author);
    }
}

public class Library {
    public static void main(String[] args) {
        Book book1 = new Book();
        book1.title = "Java Basics";
        book1.author = "Alice";

        Book book2 = new Book();
        book2.title = "Data Structures";
        book2.author = "Bob";

        // Call printDetails on book1 and book2
        // Your code here
    }
}

💡 Need a hint?

Use book1.printDetails(); and book2.printDetails(); to show the book details.