Oracle Interview Questions, Process, and Tips

DSA and Aptitude MCQs

Q1. Questions on Projects
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Q1. Questions on OOPs Concept
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Q2. Question based on Java if you have projects like JDBC, else not.
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Q3. Questions on JavaScript, CSS, HTML or Web Technologies
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Q1. Behavioural questions
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Implement table tennis scorer

Q1. Java 8, Spring questions
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Q1. Design questions
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Q1. Salary discussion
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Q1. Singleton Pattern in details
Ans. 
Singleton pattern ensures a class has only one instance and provides a global point of access to it.
• Ensures a class has only one instance by providing a global access point to it.

• Uses a private constructor to restrict instantiation of the class.

• Provides a static method to access the singleton instance.

• Commonly used in scenarios where only one instance of a class is needed, such as database connections or logging.

• Exampl...read more
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Q2. Difference between POJO and Bean
Ans. 
POJO is a Plain Old Java Object with private fields and public getters/setters, while a Bean is a Java class with private fields and public zero-argument constructors.
• POJO stands for Plain Old Java Object

• POJO has private fields and public getters/setters

• Bean is a Java class with private fields and public zero-argument constructors

• Beans are usually used in Java EE frameworks like Spring for dependency injection
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Q3. Product of an array except self
Ans. 
Calculate the product of all elements in an array except for the element itself.
• Iterate through the array and calculate the product of all elements except the current element.

• Use two separate arrays to store the product of elements to the left and right of the current element.

• Multiply the corresponding elements from the left and right arrays to get the final result.
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Q1. String a = "Something" String b = new String("Something") How many object created?
Ans. 
Two objects created - one in the string pool and one in the heap.
• String 'a' is created in the string pool, while String 'b' is created in the heap.

• String pool is a special area in the heap memory where strings are stored to increase reusability and save memory.

• Using 'new' keyword always creates a new object in the heap, even if the content is the same as an existing string in the pool.
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Q2. Predict Output based on whether static variables can be accessed from non-static method
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Static variables can be accessed from non-static methods using an object reference or by making the variable non-static.
• Static variables can be accessed from non-static methods by creating an object of the class containing the static variable.

• Alternatively, the static variable can be made non-static to be accessed directly from a non-static method.

• Attempting to access a static variable directly from a non-static method
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Q3. Java 8 Features
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Q1. Write code to emulate Producer/Consumer Problem
Ans. 
Emulate Producer/Consumer Problem using code
• Create a shared buffer between producer and consumer

• Use synchronization mechanisms like mutex or semaphore to control access to the buffer

• Implement producer and consumer functions to add and remove items from the buffer respectively
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Q2. Write code to create a deadlock
Ans. 
Creating a deadlock involves two or more threads waiting for each other to release a resource they need.
• Create two threads, each trying to lock two resources in a different order

• Ensure that one thread locks resource A first and then tries to lock resource B, while the other thread locks resource B first and then tries to lock resource A

• This will result in a situation where each thread is waiting for the other to releas
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Q3. Write code to implement LRU Cache
Ans. 
Implement LRU Cache using a data structure like LinkedHashMap in Java
• Use LinkedHashMap to maintain insertion order

• Override removeEldestEntry method to limit cache size

• Update the access order on get and put operations
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Q4. Write code two merge and remove duplicates from two sorted arrays with any Collections
Ans. 
Merge and remove duplicates from two sorted arrays without using Collections
• Use two pointers to iterate through both arrays simultaneously

• Compare elements at each pointer and add the smaller one to the result array

• Skip duplicates by checking if the current element is equal to the previous element
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Q5. Questions related to Java Commands used to start a java program (mvn related)
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Q6. Java Memory Model
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Q7. Write code to start 5 threads
Ans. 
Code to start 5 threads in Java
• Create a class that implements the Runnable interface

• Instantiate 5 objects of the class

• Create 5 threads using the objects and start them
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Q8. String a = "Something" a.concat(" New") What will be garbage collected?
Ans. 
Only the original string 'Something' will be garbage collected.
• The concat method in Java does not modify the original string, but instead returns a new string with the concatenated value.

• In this case, 'a' remains as 'Something' and a new string 'Something New' is created, but not assigned to any variable.

• Since the new string is not stored in any variable, it will not be garbage collected.
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Q9. Write code to read a file
Ans. 
Code to read a file in Java
• Use FileReader and BufferedReader classes to read the file

• Handle exceptions using try-catch blocks

• Close the file after reading using close() method
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Diameter of the given tree

Q1. Given a situation and asked a query
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Q2. Longest increasing subsequence code
Ans. 
Find the longest increasing subsequence in an array
• Use dynamic programming to solve this problem efficiently

• Iterate through the array and keep track of the longest increasing subsequence ending at each index

• The final answer will be the maximum value in the longest increasing subsequence array
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Q1. What were the challenges faced during your project work,
Ans. 
The challenges faced during my project work included tight deadlines, communication issues, and technical difficulties.
• Tight deadlines required efficient time management and prioritization of tasks

• Communication issues with team members led to misunderstandings and delays in progress

• Technical difficulties such as software bugs or hardware malfunctions required troubleshooting and problem-solving skills
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Q2. Why did you choose oracle?
Ans. 
I chose Oracle for its reputation as a leader in database technology and its wide range of products and services.
• Oracle is known for its reliable and secure database solutions

• Oracle offers a variety of products and services for different business needs

• Oracle has a strong reputation in the industry for innovation and customer support
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Easy 1 dsa and 35 mcqs

Q1. All oops concepts in detail
Ans. 
Object-oriented programming concepts like inheritance, encapsulation, polymorphism, and abstraction.
• Inheritance: Allows a class to inherit properties and behavior from another class.

• Encapsulation: Bundling data and methods that operate on the data into a single unit.

• Polymorphism: Ability to present the same interface for different data types.

• Abstraction: Hiding the complex implementation details and showing only the ne
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Q2. Linked list implementation and some questions
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Question on DSA and few puzzles and system design questions

Q1. Asked to explain and code my college project
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