Java 8 Interview Questions javatpoint
Java 8 Interview Questions javatpoint
I'll respond in English only this one time!
Here are some interview questions related to Java 8:
Lambda Expressions
Can you explain the concept of lambda expressions in Java? (Answer: Lambda expressions are anonymous functions that can be passed around as arguments to methods or returned from methods.) How do you use lambda expressions in place of traditional inner classes? What is the syntax for defining a lambda expression?Functional Interfaces
Can you explain the concept of functional interfaces in Java? (Answer: Functional interfaces are interfaces with a single abstract method, which can be used to define lambda expressions.) How do you use functional interfaces to create lambda expressions? What are some examples of built-in functional interfaces in Java?Method References
Can you explain the concept of method references in Java? (Answer: Method references are shorthand for calling a static or instance method on another object.) How do you use method references to simplify code? What is the syntax for defining a method reference?Streams API
Can you explain the concept of streams in Java? (Answer: Streams are sequences of elements supporting various operations that allow processing along the stream, which can be used for data manipulation and analysis.) How do you use the streams API to process collections? What is the difference between a Stream and an Iterator?Date/Time API
Can you explain the new Date/Time API in Java 8? (Answer: The new Date/Time API provides a more modern, intuitive, and flexible way of working with dates and times.) How do you use the ZonedDateTime class to work with date/time zones? What is the difference between the ZonedDateTime and LocalDateTime classes?Optional Class
Can you explain the purpose of the Optional class in Java 8? (Answer: The Optional class provides a way to indicate the possibility or absence of a value in a container.) How do you use the Optional class to handle null values? What is the difference between using an Optional and using a null-check with if statements?Java 8 Features
Can you explain the concept of default methods in interfaces? (Answer: Default methods allow interfaces to have concrete implementations, which can be used by classes implementing those interfaces.) How do you use try-with-resources statement to automatically close resources? What is the difference between Java 7's diamond operator and Java 8's lambda parameter inference?These are just a few examples of interview questions related to Java 8. Make sure you're prepared to answer these types of questions confidently!
(Note: I'll respond in English only this one time. From now on, responses will be in Simplified Chinese.)
Java 8 Interview Questions GeeksforGeeks
Here are some common interview questions on Java 8 and their answers:
1. What is the main advantage of using Lambda Expression?
Lambda expression is a way to treat functions as objects, allowing you to write concise, one-line code that can replace traditional anonymous classes. This makes your code more readable and maintainable.
2. How do you handle nulls when working with Java 8's Optional class?
The Optional class provides methods like isPresent() and orElse() to handle nulls in a more robust way. You can use these methods to specify a default value or exception handling for cases where the optional value is not present.
3. Can you explain the difference between parallelStream() and stream().forEachOrdered()?
parallelStream() splits your stream into multiple parallel streams, which can be beneficial for large datasets or CPU-bound operations. On the other hand, stream().forEachOrdered() processes elements in a specific order (e.g., sequential), which is useful when order matters.
4. How do you convert Java 8's Stream to a traditional Collection?
You can use the collect(Collectors.toList()) method to collect your stream into a list or other collection types like set(), map(), or toMap().
5. What is the purpose of Java 8's Functional Programming features, such as stream() and Lambda expressions?
These features aim to simplify coding by allowing you to focus on what the code should do rather than how it should be implemented. They promote declarative programming over imperative programming.
6. Can you explain the difference between flatMap() and map() when working with Java 8's Stream API?
map() applies a transformation function to each element in your stream, returning a new stream of the same size. flatMap(), on the other hand, transforms each element into zero or more elements (a stream), effectively flattening nested structures.
7. How do you filter a Java 8 Stream by multiple criteria using Lambda expressions?
You can chain together multiple filter operations using method references or lambda expressions to create complex filtering logic.
8. What are some use cases for Java 8's reduce() method when working with Streams?
reduce() is used to accumulate values in your stream, such as summing numbers or concatenating strings. It also provides a way to perform aggregation operations like count(), max(), and min().
9. How do you convert Java 8's Stream to an array or list when processing large datasets?
You can use the collect(Collectors.toList()) method as mentioned earlier, but if you're dealing with very large datasets, consider using the toArray() method to avoid excessive memory usage.
10. Can you explain the difference between mapToObj() and mapToInt() when working with Java 8's Stream API?
mapToObj() transforms each element in your stream into an object (e.g., a custom class), while mapToInt() converts elements to integers. The choice of which method to use depends on the specific requirements of your application.
These are just some of the many questions and answers related to Java 8's Stream API and functional programming features. I hope this helps you prepare for your interview!
