Java 8 Interview Questions and Answers [Updated]
Java 8 is a revolutionary update to the world’s most popular development platform. It significantly enhances the Java programming model and collective evolution of the JVM, Java language, and libraries. Java 8 contains innovations that improve productivity, simplicity of use, multilingual development, security, and speed.
The majority of these new capabilities aim to produce cleaner and more compact code. In contrast, others introduce previously unsupported functionality to Java.
Although the improvements made in Java 8 SE add to the person’s knowledge, individuals who are unaware or lose the opportunity to learn about the current changes might go through the following top list of Java 8 interview questions and answers in 2021.
Top Java 8 Interview Questions and Answers
Q1: What new features did Java 8 include?
Answer: Java 8 has several new features, the most notable of which are as follows:
- Lambda Expressions are an essential new language feature that allows us to treat actions as objects.
- Method References allow us to define Lambda Expressions by explicitly referring to processes by their names.
- Optional – a particular wrapper class used to indicate optionality.
- Functional interface – an interface with no more than one abstract method; you can indeed provide implementation via a Lambda Expression.
- Default methods help in adding full implementations in interfaces in addition to abstract forms.
- Stream API is a particular iterator class that enables us all to handle collections of objects functionally.
- Date API an improved, immutable JodaTime-inspired Date API Along with these new features, several feature improvements are made behind the scenes, mainly at the compiler and JVM levels.
Q2: What’s the distinction between the Collection API vs. Stream API?
Answer: The following are the distinctions between Collection API and Stream API:
- The Collection API was launched in JDK 1.2, while the Stream API was introduced in JDK 1.8.
- Collection objects are eagerly created, whereas Stream API objects are slowly created.
- Iterate and consume elements are unlimited times for the Collection object, but only once for the Stream object.
Q3: In Java, what is the Optional class?
Answer: In Java SE 8, a new class, Java.util.Optional is added to the util package. In a nutshell, Optional can be thought of as a single value container that either contains or does not contain the value (then it is called empty). It is used to prevent a Null Pointer Exception. Haskell and Scala contributed to the emergence of this Optional class.
Q4: What is a lambda expression?
Answer: It is an anonymous function with a set of parameters, a lambda (->), and a function body. You can name it to function without even a name.
Q5: What distinguishes Java SE 8 from others?
Answer: Java SE 8 contains the following features that set it apart from the competition.
- It generates parallel code.
- It provides even more coding options.
- It has increased application performance.
- The codes are more readable and concise.
- It facilitates the creation of databases, including promotions.
Q6. What exactly are Functional Interfaces?
Answer: A functional interface is one with only one abstract method. These interfaces are implemented using a Lambda Expression. To utilize the Lambda Expression, you must first construct a new functional interface or use an existing available interface from Java 8.
Q7: What exactly is a SAM Interface?
Answer: In Java 8, the notion of Functional Interface was introduced, which can only have one abstract method. Because these Interfaces only describe one abstract process, they are commonly referred to as SAM Interfaces, and SAM is an abbreviation for “Single Abstract Method.”
Q8: What exactly is Nashorn in Java 8?
Q9: What is a Default Method, and When Should It Be Used?
Answer: A default methodology is a technique that has an implementation and can be seen in an interface. We can utilize a default method to introduce additional functionality to an approach while keeping compatibility problems with classes that currently implement the interface.
Q10: What is the definition of a method reference in Java 8?
Answer: Method references were added to the Java programming language in Java SE 8, the most powerful version of Java. Method references in Java are an additional undeniably great feature added in Java SE 8. With the help of Method references, Lambda Expressions gain more vanity and versatility. Method references in Java SE 8 are a subset of the lambda expression that invokes (references) methods using a method name.
Method references in Java have often shortened Lambda Expressions used for method invocation, to put it simply. When the lambda expression is utilized, method references are used.
Java 8 was a significant upgrade for the language, with syntax changes, new methods, types, and under-the-hood modifications that will benefit your application even if you do not use the new language features. Oracle no longer supports Java 7; thus, businesses are being urged to upgrade to Java 8. Java 8 has numerous advantages for your company, your existing applications, and developers aiming to increase productivity. All of the main concerns addressed in this session are unique to Java 8. These are pretty common questions that you will ask in any Java interview that requires advanced skills. These ideas are necessary if you plan to take any standard Java Certification Exams, such as Oracle Certified Associate.