What functional capabilities and improvements in Java have you been using since version 8 and above?

Since Java 8 and above, I actively use the following features and improvements:

• Lambda expressions — allow writing more concise and readable code, especially when working with collections.
• Stream API — for convenient processing of collections with filtering, transformation, and data aggregation capabilities.
• Optional — for safe handling of potential null values, reducing the number of NullPointerExceptions.
• Default methods in interfaces — enable adding new methods to interfaces without breaking existing implementations.
• New methods in standard classes — for example, the java.time class introduced a new date-time API that is more convenient and safer than the old Date and Calendar classes.

Example of using Stream API and lambdas:

List<String> names = Arrays.asList("Anna", "Bob", "Charlie", "David");
List<String> filtered = names.stream()
    .filter(name -> name.startsWith("A"))
    .map(String::toUpperCase)
    .collect(Collectors.toList());

System.out.println(filtered); // [ANNA]