EPAM Systems Java Developer Interview Questions and Answers

2 coding question (1st reverse a string without changing position of special character. 2nd remove elements before '#') + 20 mcqs

How to Improve software development process

Q1. Rearrange string
Ans. 
Rearranging a string involves organizing its characters based on specific criteria, often to meet certain conditions.
• Use a frequency map to count occurrences of each character. Example: 'aabbcc' -> {'a': 2, 'b': 2, 'c': 2}.

• Sort characters based on frequency or lexicographical order. Example: 'aaabb' can be rearranged to 'ababa'.

• Check if rearrangement is possible based on character counts. If the highest frequency ex...read more
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Q2. Create form using react.js
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Creating a form in React.js involves using controlled components and managing state effectively.
• Use functional components with hooks like useState for managing form state.

• Example: const [name, setName] = useState('');

• Handle form submission with an onSubmit event handler.

• Example: <form onSubmit={handleSubmit}>...</form>

• Validate inputs before submission to ensure data integrity.

• Example: Check if fields are em...read more
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Q3. Longest prefix of strings in array
Ans. 
Find the longest common prefix among an array of strings efficiently.
• Use a vertical scanning approach: Compare characters of each string at the same index.

• Example: For ['flower', 'flow', 'flight'], the common prefix is 'fl'.

• If any string is empty, the longest prefix is also empty.

• Consider edge cases: For ['dog', 'racecar', 'car'], the longest prefix is '' (no common prefix).
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Q1. Introduce your self
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Q2. Basic hr question
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Q1. Stream api coding
Ans. 
Java Stream API allows functional-style operations on collections, enabling efficient data processing.
• Streams can be created from collections, arrays, or I/O channels. Example: List<String> names = Arrays.asList('Alice', 'Bob'); Stream<String> stream = names.stream();

• Common operations include filter, map, and reduce. Example: List<Integer> lengths = names.stream().map(String::length).collect(Collector...read more
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Q2. Interface vs abstract
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Interface defines a contract for classes to implement, while abstract class provides partial implementation.
• Interface can have only abstract methods, while abstract class can have both abstract and concrete methods.

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

• Interfaces are used for achieving multiple inheritance in Java.

• Abstract classes are used when some common functionality needs ...read more
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Q1. Microservices design pattern
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Microservices design pattern is an architectural style that structures an application as a collection of loosely coupled services.
• Each service is responsible for a specific function and can be developed, deployed, and scaled independently.

• Communication between services is typically done through APIs, allowing for flexibility and resilience.

• Microservices promote agility, scalability, and maintainability in large and com...read more
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Q2. Solid principal
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Q1. Java based questions
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Q2. Count frequency of elements using java 8
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Q1. Java + Springboot depth questions
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Q2. Permgen, metaspace
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Q1. Focused on advanced core java and spring
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Q2. Cap theorem, service discovery
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Q1. Short introduction call. Told about company, job description and position. And gave some general tips about subjects to get prepared for the tech interview...
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Q1. Java Core, Collections, OOP principles, Concurrency
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Q2. Spring Framework, Annotations, Transactional, Strings, Immutable
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Q3. ACID, Isolation Levels, Optimistic Lock
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Q4. Small coding task, preferable using Streams...
Ans. 
Filter out strings starting with 'a' and convert to uppercase using Streams
• Use Stream.filter() to filter out strings starting with 'a'

• Use Stream.map() to convert remaining strings to uppercase

• Collect the result back into an array using Collectors.toList()
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Q5. Small SQL challenge, to implement a query for given examples...
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