Onward Technologies Inc Java Software Developer Interview Questions and Answers

Q1. Given an array of non-negative integers.Find the length of the longest subsequence such that elements in the subsequence are contiguous integers. The consecutive numbers can be in any order. Example n=7 nu...read more
Ans. 
Find the length of the longest subsequence of contiguous integers in an array.
• Sort the array

• Iterate through the array and check for consecutive integers

• Keep track of the longest subsequence found
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Q2. Get list of pincodes from these objects Employee{ id Long, name String, Addresses : List
} Addresses{ houseNo long, pindcode long, state String, country String, } Ans. Use flatMap to flatten and then use m...read more
Ans. 
Use flatMap and map to extract list of pincodes from Employee objects
• Use flatMap to flatten the list of Addresses in each Employee object

• Use map to iterate over the flattened list and extract the pincodes

• Example: employeeList.stream().flatMap(emp -> emp.getAddresses().stream()).map(address -> address.getPincode()).collect(Collectors.toList())
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Q3. What is Database Pooling, Hikari and its configurations. Java 8 to current enchancements and current java version Factory and Builder design patterns to explain and code Project expalantion and details, Cr...read more
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Database pooling is a technique used to manage a pool of database connections for efficient resource utilization. HikariCP is a popular database connection pooling library in Java.
• HikariCP is a high-performance database connection pooling library for Java applications.

• It is known for its low latency and high throughput.

• Configurations for HikariCP include settings such as maximum pool size, connection timeout, and idle ...read more
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Test will be in hacker rank there would be a difficulty level between easy to medium

Q1. Question will be from data structure and easy to medium level of the programming laanguage question
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Q1. This is just to check your english ability
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Q1. Functional Programming in Java,Oops Concepts
Ans. 
Functional programming in Java focuses on using functions to perform tasks, while OOPs concepts revolve around classes and objects.
• Functional programming in Java involves using higher-order functions, lambda expressions, and streams to process data.

• OOPs concepts in Java include inheritance, encapsulation, polymorphism, and abstraction.

• Functional programming promotes immutability and avoids side effects, while OOPs allo...read more
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Q2. Spring boot related questions
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Q3. Functional Programming in java
Ans. 
Functional programming in Java focuses on using functions to perform operations on data, emphasizing immutability and avoiding side effects.
• Uses higher-order functions like map, filter, and reduce to manipulate data

• Emphasizes immutability to avoid side effects

• Encourages declarative programming style

• Leverages lambda expressions and streams for concise code

• Example: Using map to transform a list of integers
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Q1. Explain Spring Boot
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Q2. What is Redux in React
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Q3. What is Context API in React
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It was medium level java coding questions along with springboot, mcqs

Q1. ArrayList vs LinkedList
Ans. 
ArrayList is better for random access and LinkedList is better for frequent insertions and deletions.
• ArrayList uses dynamic array to store elements, allowing fast random access but slower insertions and deletions.

• LinkedList uses doubly linked list to store elements, allowing fast insertions and deletions but slower random access.

• Example: Use ArrayList when you need to frequently access elements by index. Use LinkedList...read more
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Q2. HashMap working
Ans. 
HashMap is a data structure in Java that stores key-value pairs and allows fast retrieval of values based on keys.
• HashMap is part of the Java Collections framework.

• It allows null keys and values.

• HashMap does not maintain insertion order.

• Example: HashMap map = new HashMap<>();
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Q1. Basic questions on Java concepts like OOPS, multi threading, stream. MySQL join queries
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Q2. Questions on Spring Boot and REST API
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Q1. Questions on currently working project?.
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Q2. Your contribution to the project and what challenges you faced?
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Q1. Basic Java Question
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Q2. Spring Boot related questions
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Q1. Design a rest API and code it.
Ans. 
Design and code a REST API for a software developer interview.
• Define the endpoints and HTTP methods for the API (e.g. GET /users, POST /users)

• Implement authentication and authorization mechanisms (e.g. JWT tokens)

• Use proper status codes for responses (e.g. 200 OK, 401 Unauthorized)

• Include error handling and validation for input data

• Document the API using tools like Swagger or OpenAPI
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Q2. Questions related to JPA HIBERNATE SQL
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Q1. Discussion related to Last company Project and architecture level questions
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Q2. Write code to calculate frequency of a word using Stream API and lambda expressions
Ans. 
Calculate word frequency using Stream API and lambda expressions
• Use Stream API to convert array of strings to stream

• Use Collectors.groupingBy to group words by their frequency

• Use Collectors.counting to count the occurrences of each word
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Q1. How annotation works?
Ans. 
Annotations in Java provide metadata about a program that can be used by the compiler or at runtime.
• Annotations start with the @ symbol.

• Annotations can be used to provide information to the compiler or to runtime environments.

• Annotations can be used to define custom metadata for classes, methods, fields, etc.

• Annotations can also be used for code generation, documentation, and validation.

• Examples of annotations in Java ...read more
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Q2. CondurentSkipListMap, how does it work
Ans. 
ConcurrentSkipListMap is a concurrent, sorted map implementation in Java.
• ConcurrentSkipListMap is a concurrent version of SkipListMap, which is a sorted map implementation based on skip list data structure.

• It allows multiple threads to access and modify the map concurrently.

• It provides logarithmic time complexity for most operations, making it efficient for concurrent access.

• Example: ConcurrentSkipListMap
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