Quinnox Java Developer Interview Questions and Answers

Q1. Explain Spring Boot
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Q2. What is Redux in React
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Q3. What is Context API in React
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Q1. Tell me about yourself and the project you have done
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Q2. Have you work on the spring boot freamwork
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Q3. Collection framework
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Q4. Write a program to make a Linkedlist, you have to develop the logic for the linkedlist suppose your are the first who is going to invent the linkedlist what would be the apporach how you create the add/del...read more
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Q5. Have you worked on the Data Structures
Ans. 
Yes, I have worked on various data structures like arrays, linked lists, stacks, queues, trees, and graphs.
• I have implemented algorithms using data structures like sorting, searching, and traversal.

• I have optimized code by choosing the appropriate data structure for the problem.

• I have used data structures in projects to efficiently store and manipulate data.
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Q6. Have you worked on the Multithreading
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Yes, I have experience working on Multithreading in Java.
• Implemented multithreading using Java's Thread class

• Used synchronized keyword to handle thread synchronization

• Utilized Executor framework for managing thread pools
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Q7. Write a program to find the min and max no from the array
Ans. 
Program to find min and max no from array of strings
• Iterate through the array and compare each element to find min and max

• Use Integer.parseInt() to convert strings to integers for comparison

• Initialize min and max variables with first element of array
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Q8. Difference between the @controller vs @restcontroller
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The @Controller annotation is used to create a controller class in Spring MVC, while @RestController is used to create RESTful web services.
• The @Controller annotation is used to create a controller class in Spring MVC, which is used to handle traditional web requests.

• The @RestController annotation is used to create RESTful web services, which return data in JSON or XML format.

• The @RestController annotation is a special...read more
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Q9. Difference between the @service vs @Repository
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The @Service annotation is used to mark a class as a service, while the @Repository annotation is used to mark a class as a repository.
• The @Service annotation is typically used on service layer classes, which contain business logic.

• The @Repository annotation is typically used on repository classes, which interact with a database or other data source.

• Both annotations are used for component scanning and dependency inject...read more
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Q10. Difference between the Arrylist vs Linkedlist
Ans. 
ArrayList is implemented using a dynamic array while LinkedList is implemented using a doubly linked list.
• ArrayList provides fast access to elements using index, but slow insertion and deletion.

• LinkedList provides fast insertion and deletion, but slow access to elements.

• Example: ArrayList is suitable for scenarios where random access is required, while LinkedList is suitable for scenarios where frequent insertion and d
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20 aptitude,20 comunication,4 program questions

General topics . topics about online class vs office line class

Q1. In this round also they mainly check communication.after that basic questions about the what you put on your resume
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Q1. General round. In this round they told about the company and bond
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Q1. Explain Sonarqube, different type of code smells, and how its implemented in CI CD
Ans. 
Sonarqube is a static code analysis tool used to detect code smells and bugs in code. It is integrated into CI/CD pipelines for continuous code quality checks.
• Sonarqube is a static code analysis tool that identifies code smells, bugs, and security vulnerabilities in code.

• Code smells are common programming issues that may indicate a deeper problem in the code. Examples include duplicated code, long methods, and complex ...read more
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Q2. Write a program to find the numbers divisble by 3 in a string - and reverse its indexes eg : - input : String s = "123456789" output String s = "129456783"
Ans. 
Program to find numbers divisible by 3 in a string and reverse their indexes.
• Iterate through the string and check if each character is a number divisible by 3.

• Store the divisible numbers in an array and reverse their indexes.

• Join the array back into a string and return the result.
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Q1. Difference between ArrayList and LinkedList?
Ans. 
ArrayList is implemented as a resizable array, while LinkedList is implemented as a doubly linked list.
• ArrayList provides fast random access, LinkedList provides fast insertion and deletion.

• ArrayList uses more memory as it needs to allocate a fixed size array, LinkedList uses more memory for storing references to the next and previous elements.

• Example: ArrayList is better for scenarios where random access is required, ...read more
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Q2. Difference between HashMap and HashTable?
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HashMap is non-synchronized and allows null values, while HashTable is synchronized and does not allow null values.
• HashMap is non-synchronized, meaning it is not thread-safe, while HashTable is synchronized and thread-safe.

• HashMap allows null values for both keys and values, while HashTable does not allow null keys or values.

• HashMap is faster than HashTable as it is non-synchronized, but HashTable is preferred in multi...read more
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Q1. Micro service disadvantage
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Microservices can introduce complexity, communication overhead, and potential performance issues.
• Increased complexity due to managing multiple services

• Communication overhead between services

• Potential performance issues due to network latency

• Difficulty in maintaining consistency across services
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Q2. @functionalinterface can we extend or not, map & flatmap
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No, @FunctionalInterface cannot be extended. Map and flatMap are default methods in the interface and cannot be overridden.
• No, @FunctionalInterface cannot be extended as it is a single abstract method interface.

• Map and flatMap are default methods in the interface and cannot be overridden.

• Example: public interface MyInterface { void myMethod(); default void myDefaultMethod() { // implementation } }
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Q1. Handler methods
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Q2. Default methods in java8
Ans. 
Default methods in Java 8 allow interfaces to have method implementations.
• Introduced in Java 8 to provide backward compatibility for interfaces

• Can have method implementations in interfaces using the 'default' keyword

• Used to add new methods to interfaces without breaking existing implementations
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Q1. Java8 coding to filter the vowels
Ans. 
Using Java8 to filter vowels from an array of strings
• Use Java8 stream and filter to iterate through each string in the array

• Use a lambda expression to check if each character is a vowel

• Collect the filtered strings into a new array
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Q2. Java8, Multi Threading, Hibernate, JPA
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