Optum Global Solutions Java Developer Interview Questions and Answers

Java 8 introduced lambda expressions, Java 11 added local-variable syntax for lambda parameters, and Java 17 included sealed classes and pattern matching.

• Java 8 introduced lambda expressions for functional programming.

• Java 11 added local-variable syntax for lambda parameters to simplify code.

• Java 17 included sealed classes to restrict inheritance and pattern matching for instanceof checks and type casts.

Count the number of words in a given string.

• Split the string by spaces and count the number of resulting elements.

• Handle edge cases like multiple spaces or empty strings.

• Consider punctuation marks as part of words unless specified otherwise.

Primitive data types are basic data types provided by the programming language, while non-primitive data types are created by the programmer.

• Primitive data types include int, float, double, char, boolean, etc.

• Non-primitive data types include arrays, classes, interfaces, etc.

• Primitive data types store actual values, while non-primitive data types store references to objects.

Access modifiers control the visibility of classes, methods, and variables. Non-access modifiers provide additional functionality.

• Access modifiers: public, private, protected, default

• Non-access modifiers: static, final, abstract, synchronized

• Example: public class MyClass { private int myVar; }

Java 8 features include lambda expressions, functional interfaces, streams, and more.

• Lambda expressions allow concise syntax for defining anonymous functions.

• Functional interfaces can have only one abstract method and are used for lambda expressions.

• Streams provide a way to process collections of objects in a functional style.

• Optional class helps to avoid NullPointerException by wrapping a value that may be null.

CICD tools automate the process of building, testing, and deploying code changes.

• Popular CICD tools include Jenkins, GitLab CI/CD, CircleCI, and Travis CI

• These tools help in automating the software development lifecycle

• They enable continuous integration, continuous delivery, and continuous deployment

• CICD tools help in improving code quality, reducing manual errors, and increasing development speed

Containerization is a lightweight, portable, and self-sufficient way to package and run applications.

• Containerization involves encapsulating an application and its dependencies into a container image.

• Containers are isolated from each other and share the host OS kernel.

• Popular containerization platforms include Docker and Kubernetes.

• Containerization allows for easy deployment and scaling of applications.

Indexing in SQL is a technique used to improve the performance of queries by creating a data structure that allows for faster retrieval of data.

• Indexes are created on columns in a database table to speed up the retrieval of rows that match a certain condition in a query.

• They work similar to the index in a book, allowing the database to quickly locate the rows that satisfy the query.

• Indexes can be created using a single...read more

A program to check if a given number is prime or not.

• Create a function to check if a number is prime by iterating from 2 to the square root of the number.

• If the number is divisible by any number other than 1 and itself, it is not prime.

• Handle edge cases like 0, 1, and negative numbers separately.

To find the 3rd highest salary employee, we can use a SQL query with the 'LIMIT' and 'OFFSET' keywords.

• Use a SQL query to select distinct salaries in descending order

• Use 'LIMIT 1 OFFSET 2' to get the 3rd highest salary

• Join this result with the employee table to get the employee details