Oracle Interview Questions and Answers

It was a coding round interview along with interviewer via Virtual mode. I was given 2 coding questions on HackerRank for the interview:

1. one was an easy problem on counting minimum replacements.
2. "pat is an ordinary kid who works hard to be a great runner...." this was a challenging problem (which I managed to solve).
3. I was asked some basic Python questions, as the role was for a Python Developer.

Q1. LLD for Parking Lot
Ans. 
Design a parking lot system to manage parking spaces, vehicles, and payment processing.
• Define core classes: ParkingLot, ParkingSpace, Vehicle, Ticket, and Payment.

• ParkingLot manages multiple ParkingSpaces and keeps track of available spots.

• ParkingSpace can be of different types: Compact, Regular, and Handicapped.

• Vehicle class holds information like license plate, size, and type.

• Ticket class generates a unique ID for ea...read more
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Q2. Which database are you going to use for Parking lot and Why ?
Ans. 
I would use a relational database like MySQL for the Parking lot as it provides structured data storage and supports complex queries.
• Relational databases like MySQL offer structured data storage for parking lot information

• Supports complex queries for managing parking lot data efficiently

• Ability to handle large amounts of data and transactions

• Provides data integrity and security features

• Can easily integrate with other s...read more
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Q3. Questions related to OOPs
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Q4. Questions related to Multi Threading
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Q5. Questions related to Projects
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Q1. I hate this since i was informed that this round was a technical.
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Q2. Usual Mangerial questions, Project Related, etc
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Round 1: HackerRank Test (100 Minutes)
1 DSA question (medium level, binary search on answers)
20 technical questions (OS, DBMS, CN, and other CS fundamentals)
15 general aptitude and communication questions

Q1. What is static and dynamic binding in java
Ans. 
Static binding is resolved at compile time while dynamic binding is resolved at runtime in Java.
• Static binding is also known as early binding.

• Dynamic binding is also known as late binding.

• Example of static binding: method overloading.

• Example of dynamic binding: method overriding.
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Q2. Sort the linked list
Ans. 
Sorting a linked list involves rearranging the nodes in a specific order.
• Iterate through the linked list and compare each node with the next one

• Use a sorting algorithm like bubble sort, merge sort, or quick sort to rearrange the nodes

• Update the pointers to connect the nodes in the sorted order
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Q3. What are JAR files?
Ans. 
JAR files are Java Archive files that store multiple Java class files and related metadata.
• JAR files are used to package Java classes, resources, and metadata into a single file.

• They are commonly used for distributing Java libraries or applications.

• JAR files can be created using the 'jar' command in Java.

• They can also be executed using the 'java -jar' command.

• Example: mylibrary.jar contains all the class files and reso...read more
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Q4. Singleton Class example
Ans. 
A Singleton class is a class that can only have one instance created at a time.
• Singleton classes are often used for managing resources that should only have one instance, such as a database connection.

• To implement a Singleton class, you typically make the constructor private and provide a static method to access the single instance.

• Example: Singleton class for logging system where only one instance of the logger is nee...read more
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Q5. CAP Theorem and its trade-offs
Ans. 
CAP Theorem states that in a distributed system, it is impossible to simultaneously guarantee consistency, availability, and partition tolerance.
• Consistency: All nodes in the system have the same data at the same time.

• Availability: Every request gets a response, even if some nodes are down.

• Partition Tolerance: The system continues to operate despite network partitions.

• Trade-offs: In a distributed system, you can only h...read more
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Q6. Given 2–3 tables, wrote SQL queries based on joins and basic subqueries
Ans. 
SQL queries using joins and subqueries to retrieve data from multiple tables.
• Use INNER JOIN to combine rows from two or more tables based on a related column.

• Example: SELECT * FROM Orders INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID;

• LEFT JOIN retrieves all records from the left table and matched records from the right table.

• Example: SELECT * FROM Products LEFT JOIN Categories ON Products.CategoryID ...read more
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Q7. Explain wait() and signal()
Ans. 
wait() and signal() are functions used for synchronization in multithreading.
• wait() is used to make a thread wait until a certain condition is met

• signal() is used to wake up a waiting thread when the condition is met

• Example: Producer-consumer problem where producer signals consumer to consume when a new item is produced
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Q1. Design schema and draw ER diagram for Airport Management System
Ans. 
Airport Management System schema and ER diagram design
• Entities: Airport, Flight, Passenger, Employee, Schedule

• Attributes: Airport (code, name, location), Flight (number, destination, departure time), Passenger (name, age, contact info), Employee (ID, name, role), Schedule (flight number, date, time)

• Relationships: Airport has many Flights, Flight has many Passengers, Employee works at Airport, Flight has Schedule
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Q2. Normalize a given table; I normalized it up to 3NF.
Ans. 
Normalization is the process of organizing data in a database to reduce redundancy and improve data integrity.
• Identify the functional dependencies in the table

• Eliminate partial dependencies by breaking the table into multiple tables

• Eliminate transitive dependencies by further breaking down the tables

• Ensure each table has a primary key and all non-key attributes are fully functionally dependent on the primary key
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Q3. In-depth projects analysis
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Q1. Explain REST with examples
Ans. 
REST is an architectural style for designing networked applications
• REST stands for Representational State Transfer

• It uses standard HTTP methods like GET, POST, PUT, DELETE

• Resources are identified by URIs

• Data is transferred in JSON or XML format

• Example: GET request to 'https://api.example.com/users' to retrieve a list of users
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Q2. Differences between PUT and POST, and write POST method
Ans. 
PUT is used to update or replace an existing resource, while POST is used to create a new resource.
• PUT is idempotent, meaning multiple identical requests will have the same effect as a single request

• POST is not idempotent, meaning multiple identical requests may have different effects

• PUT is used to update an existing resource at a specific URI

• POST is used to create a new resource under a specific URI

• Example: PUT /users...read more
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Q3. Discussion about status codes
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Q4. Various HTTP requests and CRUD operations
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Q1. Java basic questions.
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Q2. Rest basics methods like get, post, put, delete etc
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Q3. Given a directory name, write a program to return a list of all .tst files present in the directory and its sub directories.
Ans. 
Program to return list of .tst files in given directory and subdirectories
• Use recursion to traverse through all directories and subdirectories

• Check if each file has .tst extension and add to list if true

• Use built-in functions like os.listdir() and os.path.splitext() in Python
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Q1. Difference between == and equals
Ans. 
The '==' operator is used for comparing values of primitive data types, while the 'equals' method is used for comparing objects in Java.
• Use '==' to compare primitive data types like int, char, boolean, etc.

• Use 'equals' method to compare objects like Strings, Lists, etc.

• Example: int a = 5; int b = 5; if(a == b) { // true }

• Example: String str1 = 'hello'; String str2 = 'hello'; if(str1.equals(str2)) { // true }
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Q2. Use case of abstract class and interfaces
Ans. 
Abstract classes are used to provide a common base for multiple classes, while interfaces define a contract for classes to implement.
• Abstract classes can contain both abstract and concrete methods, while interfaces can only have abstract methods.

• Abstract classes can have constructors, while interfaces cannot.

• Interfaces allow for multiple inheritance, while classes can only inherit from one abstract class.

• Abstract class...read more
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Q3. Singleton design pattern. Explain and implement (thread safe)
Ans. 
Singleton design pattern ensures a class has only one instance and provides a global point of access to it.
• Ensure a private static instance variable in the class.

• Provide a public static method to access the instance, creating it if necessary.

• Use synchronized keyword or double-checked locking to make it thread-safe.
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Q4. Merge sort. Explain and implement.
Ans. 
Merge sort is a divide and conquer algorithm that divides the input array into two halves, sorts each half, and then merges the sorted halves.
• Divide the array into two halves

• Recursively sort each half

• Merge the sorted halves back together
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Q1. What is java and explain oopes concept
Ans. 
Java is a popular programming language used for developing various applications. OOPs (Object-Oriented Programming) is a programming paradigm based on the concept of objects.
• Java is a class-based, object-oriented programming language.

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

• Encapsulation is the bundling of data and methods that operate on the data into a single unit.

• Inheritance al...read more
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Q2. What is testing explain types
Ans. 
Testing is the process of evaluating a software application to identify defects or bugs.
• Types of testing include unit testing, integration testing, system testing, acceptance testing, and regression testing.

• Unit testing involves testing individual components or modules of the software.

• Integration testing checks if different modules work together correctly.

• System testing evaluates the entire system's functionality.

• Accep...read more
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Q3. What is exceptions handling
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Q4. Locators in automation selenium
Ans. 
Locators in automation selenium are used to identify web elements on a webpage for testing purposes.
• Locators include ID, class name, name, tag name, link text, partial link text, and xpath.

• ID is the most efficient locator as it is unique for each element.

• Xpath is powerful but can be slow and brittle if not used correctly.

• Using CSS selectors can also be a good alternative to xpath.

• It is important to choose the right loc...read more
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Q1. What are some common questions related to Linux Administration?
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Q2. Can you provide details on how to write shell scripts to automate basic tasks while handling input parameters?
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Basic aptitude questions and two coding questions were asked.

Q1. Introduce yourself
Ans. 
I am a dedicated and experienced Programmer Analyst with a strong background in software development and system analysis.
• Over 5 years of experience in programming and analyzing software systems

• Proficient in languages such as Java, C++, and SQL

• Skilled in conducting system analysis and designing solutions

• Strong problem-solving and communication skills

• Previous projects include developing a web-based inventory management s...read more
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Q2. Question in dbms, skills, about oracle
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Q1. Basic hr questions
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Q2. Basic hr questions
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Q1. Questions about OOPS includes inheritence, interface, abstract classes, access specifiers
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Q2. Coding question: given a vector, return a vector where each entry in the resultant vector is the product of the remaining elements in the given vector.
Ans. 
Return a vector where each entry is the product of all other elements in the given vector.
• Use a two-pass approach: first calculate the prefix products, then the suffix products.

• Example: For input [1, 2, 3, 4], prefix products are [1, 1, 2, 6] and suffix products are [24, 12, 4, 1].

• Multiply corresponding prefix and suffix products to get the result: [24, 12, 8, 6].

• Consider edge cases: empty vector returns empty vector, ...read more
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Q3. Coding question: given a vector numbers, return the index of the vector which has the longest length palindrome
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