What books or materials on Java have you studied to deepen your knowledge?

To deepen your knowledge of Java, the following books and materials are often recommended:

• "Effective Java" by Joshua Bloch — a classic for understanding best practices and patterns.
• "Java: The Complete Reference" by Herbert Schildt — a detailed guide to the language.
• Online courses on platforms like Coursera, Udemy, where you can find courses on modern Java.
• Oracle documentation and official Java guides.
• Practical projects and reading source code of popular libraries to understand real-world application.