Java 8 Interview Questions

Java, which originated from the Oak language, was released in early 1996 with the Java Development Kit (JDK) 1.0 as its primary version. Sir James Gosling created Java in the beginning while working at Sun Microsystems. One of the most significant Java programming language releases in 2014 was Java 8, often known as JDK 8.0. Another codename for it is Spider. Oracle Corporation is currently in charge of the open-source Java project.

This post will guide you through the scope, opportunities, and interview questions for Java 8 for both experienced and novice candidates.

Unlock the secrets of Java 8’s latest features, grasp fundamental concepts, and gain valuable insights into the world of programming. Prepare to shine brightly in your interviews with these top-notch Java 8 questions, meticulously crafted to enhance your understanding and boost your career prospects.

Certainly! Here are some common Java 8 interview questions along with their answers:

1. What are the main features introduced in Java 8?
   • Lambda expressions
   • Stream API
   • Default methods in interfaces
   • Functional interfaces
   • Optional class
   • Method references
   • Date and Time API (java.time)
2. What are lambda expressions in Java 8?
   • Lambda expressions introduce a concise way to represent anonymous functions.
   • They provide a way to pass functions as arguments to other methods.
   • Lambda expressions streamline the use of interfaces that declare a single abstract method (functional interfaces).
3. What is the Stream API in Java 8?
   • The Stream API is used to process collections of objects in a functional manner.
   • It allows you to perform operations such as filter, map, reduce, and collect on collections with concise syntax.
   • Streams can be sequential or parallel, enabling easy parallelization of operations.
4. Explain the concept of default methods in interfaces.
   • Default methods allow interfaces to have methods with implementations.
   • They enable the addition of new methods to interfaces without breaking existing implementations.
   • Default methods are marked with the default keyword.
5. What is a functional interface?
   • A functional interface is an interface that contains only one abstract method.
   • It can have any number of default or static methods.
   • Functional interfaces are used to enable lambda expressions and method references.
6. What is the Optional class?
   • The Optional class is a container class used to represent a value that may or may not be present.
   • It helps to avoid null pointer exceptions by explicitly handling the absence of a value.
   • Optional provides methods to check the presence of a value and retrieve it safely.
7. What are method references in Java 8?
   • Method references provide a way to refer to methods or constructors without invoking them.
   • They are shorthand syntax for lambda expressions calling a single method.
   • Method references can be used to improve the readability of code.
8. How does the Date and Time API (java.time) in Java 8 improve upon the previous date and time classes?
   • The java.time API provides a more comprehensive and flexible way to work with dates and times.
   • It addresses the shortcomings of the old Date and Calendar classes, such as immutability, thread-safety, and ease of use.
   • The java.time API introduces classes like LocalDate, LocalTime, LocalDateTime, ZonedDateTime, Duration, and Period for representing dates, times, and durations.

These questions cover some of the key features introduced in Java 8 and are commonly asked in interviews to assess a candidate’s understanding of the Java 8 platform.