Fidelity Investments Java Developer Interview Questions and Answers

Q1. Stringbuilder and string buffer diff
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Q2. Where we store the object of string
Ans. 
Objects of String are stored in the String Pool in Java.
• String objects are stored in the String Pool, a special memory area in Java heap memory.

• String literals are automatically stored in the String Pool.

• String objects created using the new keyword are not stored in the String Pool.

• String.intern() method can be used to store a String object in the String Pool.
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Q3. What is bean in springboot
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A bean in Spring Boot is a Java object that is instantiated, assembled, and managed by the Spring IoC container.
• Beans are defined in the Spring configuration file or using annotations like @Component, @Service, @Repository, etc.

• Beans are singleton by default but can be scoped as prototype, request, session, etc.

• Beans are injected into other beans using dependency injection.

• Example: @Component annotation is used to defi
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Q4. What is query parameters and path param
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Query parameters are used to pass data to a web server through the URL, while path parameters are part of the URL itself.
• Query parameters are key-value pairs added to the end of a URL after a '?'

• Path parameters are variables within the URL path itself, denoted by curly braces {}

• Example of query parameter: www.example.com/api/users?id=123

• Example of path parameter: www.example.com/api/users/{userId}
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Q5. Code snippet related to exception
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Q6. Diff between exception and error
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Exceptions are recoverable errors that can be handled in code, while errors are unrecoverable issues that usually result in program termination.
• Exceptions are checked at compile time, while errors are unchecked.

• Exceptions are subclasses of Throwable, while errors are subclasses of Error.

• Examples of exceptions include FileNotFoundException, NullPointerException, while examples of errors include OutOfMemoryError, StackOv
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Q1. Quick sort - keep order same
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Q2. Reverse string with spaces but keep the space position intact
Ans. 
Reverse a string while keeping the position of spaces intact
• Split the string into an array of characters

• Iterate through the array and reverse the characters while keeping track of space positions

• Join the array back into a string
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Q1. Ask to write code for equal and hashcode in notepad
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Q2. Type of Collections and its internal working
Ans. 
Java collections are data structures that store and manipulate groups of objects.
• Types of collections include List, Set, Map, Queue, etc.

• Internal workings involve data structures like arrays, linked lists, hash tables, etc.

• Collections framework provides interfaces and classes for working with collections.
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Q3. Count number of occurrence of string from Array
Ans. 
Count occurrences of a specific string in an array of strings.
• Iterate through the array and use a HashMap to store the count of each string.

• Use the string as key and increment the count each time it is encountered.

• Return the count of the specific string at the end.
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Q4. Write a code using stream
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Using stream to filter a list of strings
• Use the filter method to apply a predicate to each element in the stream

• Convert the stream back to a list using the collect method
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Q1. 1) How do you achieve concurrency in your current job, and write code for it? 2) Write code for Rest API using Springboot, need to write Entity, Service, Repository, and Controller classes? 3)Volatile keyw...read more
Ans. 
Answers to common Java Developer interview questions
• 1) Concurrency is achieved using multithreading in Java. Use threads, executors, or synchronized blocks. Example: using ExecutorService to run multiple tasks concurrently.

• 2) Rest API in Springboot: Entity class defines database table, Service class contains business logic, Repository class interacts with database, Controller class handles HTTP requests.

• 3) Volatile key...read more
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Q1. Java 8 features, functional Interfaces and predefined functional interfaces, Streams
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Q2. Collections, Aggregations, solid principles in Java
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Q3. Design patterns, singleton and factory explain in detail
Ans. 
Design patterns are reusable solutions to common problems in software design. Singleton ensures a class has only one instance, while factory creates objects without specifying the exact class.
• Design patterns are best practices for solving common software design problems.

• Singleton pattern ensures a class has only one instance and provides a global point of access to it.

• Factory pattern creates objects without specifying ...read more
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Q4. Spring functions, Spring Runners, Spring Exception handling
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Q5. Springboot annotations except common(any 5)
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Q6. Write spring boot program to accept json as request. write the logic and explain
Ans. 
Create a Spring Boot program to accept JSON requests and process the data.
• Create a Spring Boot application with a REST controller to handle incoming JSON requests.

• Use @PostMapping annotation to map the endpoint for accepting JSON requests.

• Use @RequestBody annotation to bind the incoming JSON data to a Java object.

• Process the JSON data as needed in the controller method.

• Return a response as JSON if required.
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3 coding questions were given and to be solved only in java

Java coding and apptitude questions

Q1. Tell me about project
Ans. 
I worked on a project to develop a web application for an e-commerce company.
• Developed the front-end using HTML, CSS, and JavaScript

• Implemented the back-end using Java and Spring framework

• Integrated payment gateway and order management system

• Optimized database queries for improved performance
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Q2. Tell about previous company
Ans. 
I worked at XYZ Company as a Java Developer.
• Developed and maintained Java applications for XYZ Company.

• Collaborated with a team of developers to implement new features and fix bugs.

• Used Java frameworks like Spring and Hibernate to build robust and scalable applications.

• Worked on database design and optimization using SQL.

• Participated in code reviews and provided feedback to improve code quality.

• Implemented unit tests t...read more
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Q1. What are checked and unchecked exceptions?
Ans. 
Checked exceptions are exceptions that must be either caught or declared in the method signature, while unchecked exceptions do not need to be caught or declared.
• Checked exceptions are subclasses of Exception class, excluding RuntimeException and Error.

• Checked exceptions are checked at compile time, so the compiler forces the programmer to handle them.

• Unchecked exceptions are subclasses of RuntimeException and Error cl...read more
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Q2. What is the difference between Spring and SpringBoot?
Ans. 
Spring is a framework for building Java applications, while SpringBoot is a tool that simplifies the setup and configuration of Spring applications.
• Spring is a comprehensive framework that provides various modules for different functionalities like dependency injection, aspect-oriented programming, etc.

• SpringBoot is an opinionated tool that simplifies the setup and configuration of Spring applications by providing defa...read more
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