Oracle Senior Java Developer Interview Questions and Answers

Round duration - 120 Minutes
Round difficulty - Medium

The test included MCQ questions from SQL, Linux Commands, C/C++ programming, Logical Reasoning, Aptitude questions. The other section was the coding round, where 2 SQL queries and 2 coding questions were there.

Q1. 
Subarray with Equal Occurrences Problem Statement
You are provided with an array/list ARR of length N containing only 0s and 1s. Your goal is to determine the number of non-empty subarrays where the numbe...read more
Ans. 
Count the number of subarrays where the number of 0s is equal to the number of 1s in a given array of 0s and 1s.
• Iterate through the array and keep track of the count of 0s and 1s encountered so far.

• Use a hashmap to store the count of 0s and 1s encountered at each index.

• For each index, check if the count of 0s is equal to the count of 1s encountered so far and update the result accordingly.
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Q2. 
Pythagorean Triplets Detection
Determine if an array contains a Pythagorean triplet by checking whether there are three integers x, y, and z such that x² + y² = z² within the array.
Input:
The first lin...read more
Ans. 
Detect if an array contains a Pythagorean triplet by checking if there are three integers x, y, and z such that x^2 + y^2 = z^2.
• Iterate through all possible triplets of numbers in the array and check if they form a Pythagorean triplet.

• Use a nested loop to generate all possible combinations of three numbers from the array.

• Check if the sum of squares of two numbers is equal to the square of the third number for each trip...read more
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Round duration - 50 Minutes
Round difficulty - Medium

This was a standard DSA round where I was asked to solve 2 questions and also code it in a production ready manner . At the end I was also asked some questions related to Linux and SQL . I was tested on some basic commands of Linux .

Q1. 
Palindromic Substrings Problem Statement
Given a string S, your task is to return all distinct palindromic substrings of the given string in alphabetical order.
Explanation:
A string is considered a pal...read more
Ans. 
Return all distinct palindromic substrings of a given string in alphabetical order.
• Iterate through all possible substrings of the given string.

• Check if each substring is a palindrome.

• Store distinct palindromic substrings in alphabetical order.
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Q2. 
Swap Two Numbers Problem Statement
Given two integers a and b, your task is to swap these numbers and output the swapped values.
Input:
The first line contains a single integer 't', representing the num...read more
Ans. 
Swap two integers 'a' and 'b' and output the swapped values.
• Create a temporary variable to store one of the integers before swapping.

• Swap the values of 'a' and 'b' using the temporary variable.

• Output the swapped values of 'a' and 'b'.
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Q3. What is meant by normalization and denormalization?
Ans. 
Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity, while denormalization is the process of intentionally adding redundancy to improve query performance.
• Normalization involves breaking down a table into smaller tables and defining relationships between them to reduce redundancy and dependency.

• Denormalization involves combining tables or adding redundant data to...read more
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Round duration - 60 Minutes
Round difficulty - Medium

This was a DS/Algo + Core round where I was asked questions related to DBMS , SQL queries and Linux Commands . The first question was of DSA and I was able to code it preety fast . I was also asked to execute some SQL queries on my laptop.
Overall , this round went good according to my opinion.

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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Q2. How would you delete duplicate emails from a database using SQL?
Ans. 
Use SQL query with GROUP BY and HAVING clause to delete duplicate emails from a database.
• Use GROUP BY clause to group emails together

• Use HAVING clause to filter out groups with more than one email

• Use DELETE statement to remove duplicate emails
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Q3. What is the difference between the DELETE and TRUNCATE commands in a DBMS?
Ans. 
DELETE removes specific rows from a table, while TRUNCATE removes all rows and resets auto-increment values.
• DELETE is a DML command, while TRUNCATE is a DDL command.

• DELETE can be rolled back, while TRUNCATE cannot be rolled back.

• DELETE triggers ON DELETE triggers, while TRUNCATE does not trigger any triggers.

• DELETE is slower as it maintains logs, while TRUNCATE is faster as it does not maintain logs.

• Example: DELETE FRO...read more
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Round duration - 30 Minutes
Round difficulty - Easy

This was a typical HR round with some standard Behavioral questions .

Q1. What is something about you that is not included in your resume?
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Q2. Why do you want to work at Amdocs?
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