Introduction

Java 8 Interview Questions, Java is a very well-liked programming language that is used in a variety of applications, including those for Android and the Internet of Things (IoT). In fact, according to Codeplatoon, Java had the most job posts in 2019. It should come as no surprise that there is still a considerable need for knowledgeable individuals in Java given its widespread use.

What is JAVA 8?

Before we discuss the JAVA 8 interview questions, you must be conversant with JAVA 8. The most recent Java release, Java 8, includes new features, improvements, and bug fixes to increase productivity when creating and using Java programs. Before being made accessible for download by end users on the java.com website, the new release of Java is first made available to developers so they have enough time for testing and certification.

JAVA 8 Interview Questions

These JAVA 8 interview questions can be classified majorly into the following two  categories:

1. JAVA 8 Interview Questions for Freshers
2. JAVA 8 Interview Questions for experienced

JAVA 8 Interview Questions for Freshers

What brand-new capabilities did Java 8 bring?

The latest version has:

1. An enhanced, immutable Date and Time API inspired on JodaTime
2. A new language called Lambda Expressions considers actions as objects Method References, allowing you to define Lambda Expressions by directly referencing methods by their names.
3. In addition to abstract methods, default methods allow users to include entire implementations in interfaces.
4. JDK integrates Nashorn, a high-performance Java-based engine, to evaluate and run JavaScript code.

Why was a new version of Java needed in the first place?

1. There are two main reasons:

• Java must now make better use of multi-core CPUs due to significant hardware changes.
• enabling new functional programming (FP) features for users.

What is Type Inference?

The compiler uses type inference to examine each method invocation and accompanying declaration to help it determine the parameter types.

What is Java 8 StringJoiner class used for?

You can be asked this query during the JAVA 8 Interview questions. Java 8’s StringJoiner class builds a string by creating a sequence of characters that are separated by a delimiter, such as a hyphen or a comma so that users can generate strings using these delimiters. To know more about best data science training institute in Delhi

What is a default method, and when does it get used?

The interface has a default method that uses an implementation. Backward compatibility with classes that already implement the interface is maintained while new functionalities are added by the method.

What is a Lambda Expression, and why use them?

It is a function that is an object that may be shared and referenced. Lambda Expressions allow users to encapsulate one behavior unit to send around to other applications, need less coding, and offer a way to implement the Java 8 functional interface. During the JAVA 8 Interview questions, this query might be asked. 

what actual advantages does Java 8 bring?

The advantages include:

1. The code is clearer and easier to read
2. More reusable is the code
3. Code is easier to test and maintain.
4. Now, code is scalable and highly concurrent.
5. Users may create parallel programs.
6. Users can create operations similar to databases.
7. Applications currently work better.

What is MetaSpace? How does it differ from PermGen?

These are some of the typical JAVA 8 Interview questions that are asked.

PremGen: 

Prior to Java 8, classes’ metadata was kept in PremGen (Permanent-Generation) memory. PremGen has a set size and cannot be expanded or contracted on the fly. It was an uninterrupted Heap Memory in Java.

MetaSpace: 

The ‘MetaSpace’ native memory space in Java 8 is where the classes’ MetaData is stored. Java 8 Interview Questions, Because it is not a contiguous heap memory, it can grow dynamically, which lets it get around size restrictions. This enhances the de-allocation, auto-tuning, and garbage collection of metadata.

What are the various categories of pre-defined function interfaces?

Function: to convert input into a returnable value.

Predicate: to run a test and output a Boolean result.

Consumer: Do not return any values despite accepting arguments.

Supplier: Don’t take any arguments, just give back a value. 

Operator: Execute a reduction operation that takes the same input types.

JAVA 8 Interview Questions for Experienced

What are the features of a lambda expression?

The two key characteristics of the methods that are defined as lambda expressions are listed below: 

• Another method may accept lambda expressions as a parameter. 
• Lambda expressions can be used independently of classes.

What are Intermediate and Terminal operations?

During the JAVA 8 Interview questions, this query might be asked.

Intermediate Operations:

1. Analyze the stream’s components.
2. usually converts one stream into another.
3. are lazy, meaning they only run when a terminal operation is called.
4. carries out internal iteration on each component of the source.
5. The processing pipeline allows for the chaining of any number of activities.
6. The operations are carried out in the prescribed order.
7. Lambda functions predominate in intermediate processes.

Terminal Operations:

• enables the Stream pipeline to begin.
• used to gather the Stream data after processing.

What is the Feature of the New Date and Time API in Java 8?

1. Thread-safe classes and immutable types 
2. Timezone assistance
3. Fluent ways for constructing objects and performing maths
4. I18N issue for older APIs is fixed.
5. popular joda-time package had an influence
6. Each and every packet is based on the ISO-8601 calendar

Define Nashorn in Java 8

You must get ready for this since it will be a part of the JAVA 8 Interview questions. A JavaScript processing engine called Nashorn is included with Java 8. Compared to earlier versions, it offers higher run-time performance and better conformance with ECMA (European Computer Manufacturers Association) normalized JavaScript specifications. Click here to know more about data science course in Delhi

What is a Spliterator?

This phrase, which combines the terms “splittable” and “iterator,” is a new addition to Java SE 8. Internal iteration is used in the Stream API to iterate streams in parallel or sequential order.

What is stream pipelining?

Chaining together several procedures is known as stream pipelining. This task is completed via pipelining, which divides stream operations into intermediate operations and terminal operations. Each intermediary operation completes and returns a stream instance. As a result, a user can configure any number of intermediary actions to process data, resulting in the formation of a processing pipeline. This is a brief question that was asked by the interviewer as part of the JAVA 8 Interview Questions

What is Nashorn, and What Advantages does it Provide?

The new JavaScript processing engine, Nashorn, came pre-installed with Java 8. Mozilla Rhino was formerly used by the Java platform. Nashorn outperforms its predecessor in terms of run-time performance and better conformance with ECMA-normalized JavaScript standards.

Explain the difference between predicate and function.

PredicateT> is a single argument function that returns either true or false, despite the fact that they are both functional interfaces. Although it only takes one argument and returns an object, functionT,R> is also a single argument function. The “T” here stands for the kind of function input, Java 8 Interview Questions, while the “R” stands for the kind of outcome.

Conclusion

Java is a widely used programming language that ranks second in popularity in both the TIOBE and PYPL rankings of computer languages. The top tech companies in the world, including Twitter, LinkedIn, Amazon, PayPal, and others, construct their web applications and backend web systems using Java. Java 8 Interview Questions, Another popular language for creating apps for the Android operating system, which Google supports and actively promotes, is Java.

There are currently 1,751,661 Java-related questions on StackOverflow and 123,776 Java public repositories on GitHub, both of which are on the rise. Given that Java 8 is one of the most reliable versions, it offers a wide range of job prospects. Simply comprehend the ideas, put them into practice, and become ready for the interviews!

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