What are the main advantages and disadvantages of using Java 8 in projects?

Java 8 brought many improvements that made development more convenient and expressive:

Advantages:

• Lambda expressions and functional interfaces — allow writing more compact and readable code, especially when working with collections.
• Stream API — simplifies collection processing, supports parallel operations, which can improve performance.
• New methods in interfaces (default and static) — enable extending interfaces without breaking backward compatibility.
• Optional — helps avoid NullPointerException and improves handling of potential null values.
• New date and time API (java.time) — more convenient and safer compared to outdated Date and Calendar.

Disadvantages:

• Backward compatibility with legacy code — sometimes new features may conflict with existing code.
• Learning curve — for some developers, the functional style may be unfamiliar.
• Performance — in some cases, using Stream API and lambdas can be less efficient than traditional loops, especially in performance-critical areas.

Overall, Java 8 significantly expanded the language's capabilities and improved code expressiveness, but requires understanding new concepts and conscious application.