YASH Technologies Senior Java Developer Interview Questions and Answers

Q1. Java 8 Default Method
Ans. 
Java 8 Default Method allows interfaces to have method implementations.
• Introduced in Java 8 to provide backward compatibility for interfaces

• Can have method implementations in interfaces using the 'default' keyword

• Used to add new methods to interfaces without breaking existing implementations
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Q2. Sort Array with given value
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Sort array of strings with a given value
• Use Arrays.sort() method with a custom Comparator to sort the array based on the given value

• Handle cases where the given value is not present in the array

• Example: Sort array ['apple', 'banana', 'orange', 'grape'] with 'banana' as the given value
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Q3. SQL Queries on Joins
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There were MCQ questions consists of different sections like Design Pattern,Java 8

Q1. Questions related to Multithreading,Design patterns
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Q2. Java coding questions
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Q1. Questions related to Multithreading
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Q2. Java coding questions
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Q1. Core java oops concepts
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Q2. Angular basic topics
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Q1. Spring boot topics
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Q2. Oracle queries examples
Ans. 
Examples of Oracle queries
• Use SELECT statement to retrieve data from a table

• Use WHERE clause to filter results based on a condition

• Use JOIN to combine rows from two or more tables based on a related column
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Q1. Discussed about my carrer details
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Q2. Expected CTC discussed
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Q1. DESCRIBE TYPES JVM MEMORY.
Ans. 
JVM memory consists of Young Generation, Old Generation, and Permanent Generation.
• Young Generation: where new objects are allocated and aged before moving to Old Generation.

• Old Generation: where long-lived objects are stored.

• Permanent Generation: where metadata such as class definitions and method information are stored.
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Q2. DIFFERENCE BETWEEN INTERFACE AND ABSTRACT CLASS.
Ans. 
Interface is a contract with no implementation, while abstract class can have some implementation.
• Interface cannot have any method implementation, while abstract class can have some method implementations.

• A class can implement multiple interfaces, but can only extend one abstract class.

• Interfaces are used to achieve multiple inheritance in Java.

• Abstract classes can have constructors, while interfaces cannot.

• Example: In...read more
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Q3. HOW TO CREATE OUR OWN IMMUTABLE CLASS? WHY IMMUTABLE CLASS
Ans. 
Immutable classes in Java are classes whose objects cannot be modified once they are created.
• Make the class final to prevent inheritance

• Make all fields private and final

• Do not provide setter methods for fields

• Ensure that any mutable objects within the class are also immutable
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Q4. WHAT IS DIFFERENCE BETWEEN COMPOSITION AND AGGREGATION ?
Ans. 
Composition is a strong relationship where the child object cannot exist independently of the parent object, while aggregation is a weak relationship where the child object can exist independently.
• Composition is a 'has-a' relationship, where the child object is a part of the parent object.

• Aggregation is a 'has-a' relationship, where the child object is not a part of the parent object.

• In composition, the child object is...read more
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Q5. DIFFERENCE BETWEEN COMPARABLE AND COMPARATOR.
Ans. 
Comparable is an interface used for natural ordering of objects, while Comparator is an interface used for custom ordering of objects.
• Comparable interface is implemented by the class whose objects are to be compared, while Comparator interface is implemented by a separate class.

• Comparable interface has a single method compareTo() for comparing objects, while Comparator interface has a single method compare() for custom...read more
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Q6. DIFFERENCE BETWEEN HASHMAP AND CONCURRENTHASH MAP
Ans. 
HashMap is not thread-safe while ConcurrentHashMap is thread-safe.
• HashMap is not thread-safe and can lead to ConcurrentModificationException if modified during iteration.

• ConcurrentHashMap allows concurrent read and write operations without the need for external synchronization.

• ConcurrentHashMap achieves thread-safety by dividing the map into segments, allowing multiple threads to operate on different segments concurren...read more
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Q7. DIFFERENCE BETWEEN COLLECTION AND STREAM
Ans. 
Collections store data while streams process data in a functional way.
• Collections are used to store and manage groups of objects, while streams are used to process collections of objects.

• Collections are mutable, meaning you can add, remove, or modify elements, while streams are immutable and do not change the original data.

• Streams use functional programming concepts like map, filter, and reduce to process data efficien...read more
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Q8. IN WHICH SITUATION WE USE @PRIMARY AND @ QUALIFIER ?
Ans. 
Use @Primary to specify a primary bean when multiple beans of the same type are present. Use @Qualifier to specify a specific bean when multiple beans of the same type are present.
• Use @Primary to indicate the primary bean to be used when multiple beans of the same type are present in the Spring application context.

• Use @Qualifier along with @Autowired to specify a specific bean to be injected when multiple beans of the ...read more
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Java8 stream api related problems to code in notepad

Q1. How to use zipkin in microservices
Ans. 
Zipkin is a distributed tracing system used to monitor microservices communication.
• Add Zipkin dependencies to each microservice

• Configure each microservice to send tracing data to Zipkin server

• Use Zipkin UI to visualize and analyze the tracing data

• Add trace IDs to logs for better debugging

• Use Zipkin to identify performance bottlenecks and optimize microservices communication
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Q2. Why we need micro services
Ans. 
Microservices allow for modular and scalable software development.
• Microservices break down large applications into smaller, independent services.

• Each service can be developed, deployed, and scaled independently.

• This allows for greater flexibility and agility in software development.

• Microservices also promote better fault isolation and easier maintenance.

• Examples of companies using microservices include Netflix, Amazon,
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Q1. Design for bruteforce method to address ondemand requirement
Ans. 
Bruteforce method for ondemand requirement design
• Identify the problem and define the scope

• Determine the possible inputs and outputs

• Create a brute force algorithm to solve the problem

• Optimize the algorithm to reduce time complexity

• Test the algorithm with various inputs and edge cases
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Q1. Questions related to Multi threading, Exception Handling, Streams, Springboot annotations, Microservices were asked.
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