What materials or resources have you used to study the topic?

The following resources are often used for learning Java:

• Official Oracle documentation (Java SE Documentation) — the most authoritative source.
• Books: for example, "Java: The Complete Reference" by Herbert Schildt or "Effective Java" by Joshua Bloch.
• Online courses on platforms like Coursera, Udemy, Stepik.
• Practical exercises and projects on GitHub.
• Communities and forums such as Stack Overflow and Russian-speaking Java communities.

A combination of theory and practice helps to better understand the material.