DCB Bank Java Developer Interview Questions and Answers

Q1. What is one keyword which can be used so that value of variable cannot be changed
Ans. 
final keyword can be used to make a variable's value constant and unchangeable
• Use 'final' keyword before the variable declaration

• Once a variable is declared as final, its value cannot be changed

• Example: final int num = 10; // value of num cannot be modified
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Q2. Have you heard about deadlock ?
Ans. 
Yes, deadlock is a situation in concurrent programming where two or more threads are waiting for each other to release resources, causing them to be stuck indefinitely.
• Deadlock occurs when two or more threads are blocked forever, waiting for each other to release resources.

• It can happen when multiple threads have locks on different resources and each thread is trying to acquire a lock held by another thread.

• Example: Th...read more
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Q3. Tell the approach to print the unique elements from a arraylist
Ans. 
Use a HashSet to store unique elements from the arraylist
• Create a HashSet and add all elements from the arraylist to it

• Since HashSet does not allow duplicates, only unique elements will be stored

• Convert the HashSet back to an arraylist if needed
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Q4. When can a conflict arise while working with git and github
Ans. 
Conflicts can arise in git and github when multiple developers make changes to the same file or branch simultaneously.
• Conflicts can occur when two developers make changes to the same line of code in a file.

• Conflicts can also arise when merging branches that have diverged and contain different changes.

• Communication among team members is crucial to avoid conflicts and resolve them efficiently.

• Using pull requests and code...read more
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Q5. Why spring has came into picture? What are the features it provides
Ans. 
Spring came into picture to simplify Java development by providing features like dependency injection, aspect-oriented programming, and transaction management.
• Spring provides dependency injection which helps in managing object dependencies and promotes loose coupling.

• It supports aspect-oriented programming for separating cross-cutting concerns like logging, security, and transaction management.

• Spring offers robust tran...read more
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Q6. What is polymorphism
Ans. 
Polymorphism is the ability of a single function or method to operate on different types of data.
• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• There are two types of polymorphism: compile-time (method overloading) and runtime (method overriding).

• Example: A superclass Animal with methods eat() and sleep(). Subclasses Dog and Cat override these methods with their own imp
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Q7. What is collection framework
Ans. 
Collection framework in Java is a set of classes and interfaces that provide a way to store and manipulate groups of objects.
• It provides a way to store, retrieve, and manipulate groups of objects.

• It includes interfaces like List, Set, and Map, and classes like ArrayList, HashSet, and HashMap.

• Collections framework simplifies the process of working with collections of objects in Java.
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Q8. Difference between map and set
Ans. 
Map is a collection of key-value pairs where keys are unique, while Set is a collection of unique elements with no duplicates.
• Map allows duplicate values but keys must be unique

• Set does not allow duplicate elements

• Map is accessed using keys, while Set is accessed using elements

• Example: Map - {1: 'apple', 2: 'banana'}, Set - {'apple', 'banana'}
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Q9. Which is best choice arraylist or linkedlist when space is not an issue?
Ans. 
ArrayList is a better choice when space is not an issue due to its constant time access, while LinkedList has better performance for insertions and deletions.
• ArrayList is better for random access as it provides constant time access to elements based on index.

• LinkedList is better for insertions and deletions as it does not require shifting elements in memory.

• Example: If you need to frequently add or remove elements in a...read more
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Q10. Do you know about javafx jsp
Ans. 
JavaFX is a software platform for creating and delivering desktop applications, while JSP is a technology used for creating dynamic web pages.
• JavaFX is used for creating rich internet applications with a modern look and feel.

• JSP is used for developing dynamic web pages with Java code embedded in HTML.

• JavaFX and JSP can be used together to create interactive web applications.
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25 MCQs mainly on core java, design patterns, synchronization

Q1. Given an assignment to write program on Fibonacci series, String palindrome Threads in Java, Java Streams
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Q2. Questions about data structures and collection API
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Java and sql questions

Q1. Basics of java ans core java
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Q1. Java related questions
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Q2. Microservices related questions
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Q1. How do you balance work and life ?
Ans. 
I prioritize my work and set boundaries to ensure a healthy work-life balance.
• I prioritize my tasks and set realistic goals to manage my workload effectively.

• I establish clear boundaries between work and personal life to avoid burnout.

• I practice time management techniques, such as creating schedules and prioritizing tasks.

• I make sure to take breaks and engage in activities outside of work to recharge.

• I communicate open...read more
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Q2. What is a positive quote for work ?
Ans. 
A positive quote for work can inspire and motivate individuals to achieve their goals and excel in their professional endeavors.
• A positive attitude leads to positive outcomes.

• Hard work and dedication are the keys to success.

• Believe in yourself and your abilities.

• Success is not final, failure is not fatal: It is the courage to continue that counts.

• The only way to do great work is to love what you do.

• Don't watch the cloc...read more
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It was spring boot java based online round

Q1. Optional in java.
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Q2. Eager and lazy initialization in simgleton design pattern
Ans. 
Eager initialization creates the instance of Singleton class at the time of class loading, while lazy initialization creates the instance only when it is required.
• Eager initialization can lead to resource wastage if the instance is never used.

• Lazy initialization is more efficient as it only creates the instance when needed.

• Eager initialization is thread-safe by default, while lazy initialization requires synchronizatio...read more
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Q1. Rest api questions
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Q2. Core java and springboot
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Q1. Why string is immutable
Ans. 
String is immutable in Java to ensure thread safety, security, and optimization.
• Immutable strings are thread-safe as they cannot be modified concurrently by multiple threads.

• String pooling is possible due to immutability, saving memory and improving performance.

• Security is enhanced as sensitive information stored in strings cannot be altered.

• Examples: String str = "Hello"; str.concat(" World"); // str remains "Hello"
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Q2. What is spring aop
Ans. 
Spring AOP (Aspect-Oriented Programming) is a framework that provides cross-cutting concerns in a modular way.
• Spring AOP allows separating cross-cutting concerns from the main application logic.

• It enables developers to define aspects (cross-cutting concerns) separately and apply them to multiple classes.

• Examples of cross-cutting concerns include logging, security, and transaction management.
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