Some of the key features and enhancements in Java 8 include:

1. Lambda Expressions: Lambda expressions allow you to write more concise and expressive code. They introduce a new syntax for defining anonymous functions, which is particularly useful when working with functional interfaces.

   Example:

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   // Traditional approach Runnable runnable = new Runnable() { public void run() { System.out.println("Hello, World!"); } }; // Using Lambda expression Runnable runnable = () -> System.out.println("Hello, World!");

2. Functional Interfaces: Functional interfaces are interfaces that have exactly one abstract method. Java 8 introduced the @FunctionalInterface annotation to explicitly mark such interfaces. Functional interfaces are commonly used with lambda expressions.

3. Stream API: The Stream API provides a new abstraction for working with sequences of data. It allows you to process collections of objects in a declarative and functional style, enabling operations like filtering, mapping, and reducing.

   Example:

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   List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5); int sum = numbers.stream() .filter(n -> n % 2 == 0) .mapToInt(Integer::intValue) .sum();

4. Default Methods: Java 8 introduced the ability to define default methods in interfaces. This allows you to add new methods to interfaces without breaking existing implementations.

   Example:

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   interface MyInterface { void myMethod(); default void myDefaultMethod() { System.out.println("Default method implementation"); } }

5. Method References: Method references provide a way to refer to methods or constructors using a shorter syntax. They are often used in conjunction with lambda expressions.

   Example:

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   List<String> names = Arrays.asList("Alice", "Bob", "Charlie"); names.forEach(System.out::println);

6. New Date and Time API: Java 8 introduced a modern date and time API in the java.time package. This API provides classes like LocalDate, LocalTime, LocalDateTime, and ZonedDateTime for more effective handling of dates and times.

7. Optional: The Optional class was introduced to address null-related issues. It encourages better handling of potentially nullable values and reduces the likelihood of null pointer exceptions.

   Example:

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   Optional<String> optionalName = Optional.ofNullable(getName());

8. Nashorn JavaScript Engine: Java 8 included the Nashorn JavaScript engine, which allows you to execute JavaScript code within Java applications.

9. Improved Concurrency: Java 8 introduced enhancements to the java.util.concurrent package, including the CompletableFuture class for asynchronous programming.