Barclays Senior Java Developer Interview Questions and Answers for Experienced

Q1. Design patterns that you have followed in your past projects.
Ans. 
I have followed the MVC, Singleton, and Factory design patterns in my past projects.
• MVC pattern for separating concerns and improving maintainability

• Singleton pattern for ensuring only one instance of a class is created

• Factory pattern for creating objects without exposing the instantiation logic
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Q2. How to secure the applications?
Ans. 
Applications can be secured by implementing various security measures such as authentication, authorization, encryption, and regular updates.
• Implement strong authentication mechanisms such as multi-factor authentication

• Use authorization to restrict access to sensitive data and functionalities

• Encrypt sensitive data both in transit and at rest

• Regularly update the application and its dependencies to patch security vulnera...read more
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Round duration - 90 minutes
Round difficulty - Easy

Q1. 
Occurrence of Each Word: Problem Statement
You are given a string S consisting of several words. Your task is to count the number of times each word appears in string S. A word is defined as a sequence of...read more
Ans. 
Count the occurrence of each word in a given string.
• Split the string into words using spaces as delimiters.

• Use a hashmap to store the count of each word.

• Iterate through the words and update the count in the hashmap.

• Output each unique word with its occurrence count.
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Round duration - 30 minutes
Round difficulty - Easy

Q1. 
Anagram Pairs Verification Problem
Your task is to determine if two given strings are anagrams of each other. Two strings are considered anagrams if you can rearrange the letters of one string to form the...read more
Ans. 
Check if two strings are anagrams of each other by comparing their sorted characters.
• Sort the characters of both strings and compare them.

• Use a dictionary to count the frequency of characters in each string and compare the dictionaries.

• Ensure both strings have the same length before proceeding with comparison.

• Handle edge cases like empty strings or strings with different lengths.
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Round duration - 45 minutes
Round difficulty - Medium

Q1. 
Palindromic Substrings Problem Statement
Find the total number of palindromic substrings in a given string STR.
Example:
Input:
"abbc"
Output:
5
Explanation:
The palindromic substrings are: ["a", "...read more
Ans. 
Count the total number of palindromic substrings in a given string.
• Iterate through each character in the string and expand around it to find palindromic substrings.

• Use dynamic programming to store previously calculated palindromic substrings.

• Consider both odd and even length palindromes while counting.

• Example: For input 'abbc', palindromic substrings are ['a', 'b', 'b', 'c', 'bb']. Total count is 5.
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Q2. How can you find the 4th highest salary from a table in a database?
Ans. 
To find the 4th highest salary from a table in a database, you can use a SQL query with the ORDER BY and LIMIT clauses.
• Write a SQL query to select distinct salaries from the table in descending order.

• Use the LIMIT clause to retrieve the 4th row from the sorted list.

• The query would look like: SELECT DISTINCT salary FROM table_name ORDER BY salary DESC LIMIT 3, 1
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Basic Aptitude and Technical Question

2 coding Questions asked from array and strings

Q1. Projects were asked
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Q2. Resume should be prepared well
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Q1. Basic HR questions were asked
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Related to the DSA and concepts of OS and CN

Q1. Palindrome question
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Q1. Explain Encapsulation
Ans. 
Encapsulation is the concept of bundling data and methods that operate on the data into a single unit.
• Encapsulation helps in hiding the internal state of an object and only exposing necessary functionalities.

• It allows for better control over the data by preventing direct access from outside the class.

• Encapsulation also helps in achieving data abstraction and information hiding.

• Example: In a class representing a car, th...read more
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Q2. How to call rest API
Ans. 
To call a REST API, you can use tools like Postman or code in languages like JavaScript or Python.
• Use tools like Postman to make HTTP requests to the API endpoints

• In programming languages like JavaScript, use libraries like Axios or Fetch to make API calls

• Include necessary headers, parameters, and authentication tokens in the request

• Handle the response data accordingly, whether it's JSON, XML, or other formats
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You have to debug and correct the code given.

Q1. Fibonacci Series
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