Middle Backend Java Developer

Description

Auto-generated position for Middle Backend Java Developer

Interview Questions (192)

Q1Can you explain how you would implement a multithreaded application in Java, and what challenges you might face?
Technical
Q2Describe a time when you had to resolve a conflict within your team. What was your approach?
Behavioral
Q3Can you explain how Spring Security manages authentication and authorization in a Java application?
Technical
Q4Describe a challenging project you worked on where you had to implement multithreading in Java. What was your role and what was the outcome?
Experience
Q5Can you explain how you would implement a RESTful API using Spring Boot and ensure it follows best practices for security?
Technical
Q6Can you explain the difference between Spring MVC and Spring WebFlux and when to use each?
Technical
Q7Is Java platform independent?
Technical
Q8What are the top Java features?
Technical
Q9What is JVM?
Technical
Q10What is JIT?
Technical
Q11What are memory storages available with JVM?
Technical
Q12What is a classloader?
Technical
Q13What is the difference between JVM, JRE, and JDK?
Technical
Q14What are the differences between Java and C++?
Technical
Q15Explain public static void main(String args[]) in Java.
Technical
Q16What is Java String Pool?
Technical
Q17What will happen if we don't declare the main as static?
Technical
Q18What are packages in Java?
Technical
Q19Why are packages used?
Technical
Q20What are the advantages of packages in Java?
Technical
Q21Explain different data types in Java.
Technical
Q22When is a byte datatype used?
Technical
Q23Can we declare a pointer in Java?
Technical
Q24What is the default value of byte datatype in Java?
Technical
Q25What is the default value of float and double datatype in Java?
Technical
Q26What is the wrapper class in Java?
Technical
Q27Why do we need wrapper classes?
Technical
Q28Differentiate between instance and local variables.
Technical
Q29What are the default values assigned to variables and instances in Java?
Technical
Q30What is a class variable?
Technical
Q31What is the default value stored in local variables?
Technical
Q32Explain the difference between instance variable and a class variable.
Technical
Q33What is a static variable?
Technical
Q34What is the difference between System.out, System.err, and System.in?
Technical
Q35What do you understand by an IO stream?
Technical
Q36What is the difference between the Reader/Writer and InputStream/OutputStream class hierarchies?
Technical
Q37What are the super most classes for all the streams?
Technical
Q38What are the FileInputStream and FileOutputStream?
Technical
Q39What is the purpose of using BufferedInputStream and BufferedOutputStream classes?
Technical
Q40What are FilterStreams?
Technical
Q41What is an I/O filter?
Technical
Q42How many ways can you take input from the console?
Technical
Q43What is the difference in the use of print, println, and printf?
Technical
Q44What are operators?
Technical
Q45How many types of operators are available in Java?
Technical
Q46Explain the difference between >> and >>> operators.
Technical
Q47Which Java operator is right associative?
Technical
Q48What is the dot operator?
Technical
Q49What is covariant return type?
Technical
Q50What is the transient keyword?
Technical
Q51What is String in Java?
Technical
Q52What are the differences between String and StringBuffer?
Technical
Q53What are the differences between StringBuffer and StringBuilder?
Technical
Q54Which among StringBuilder or StringBuffer should be preferred when there are a lot of updates required to be done in the data?
Technical
Q55Why is StringBuffer called mutable?
Technical
Q56How is the creation of a String using new() different from that of a literal?
Technical
Q57What is an array in Java?
Technical
Q58On which memory are arrays created in Java?
Technical
Q59What are the types of an array?
Technical
Q60Why does the Java array index start with 0?
Technical
Q61What is the difference between int array[] and int[] array?
Technical
Q62How to copy an array in Java?
Technical
Q63What do you understand by the jagged array?
Technical
Q64Is it possible to make an array volatile?
Technical
Q65What are the advantages and disadvantages of an array?
Technical
Q66What is an object-oriented paradigm?
Technical
Q67What are the main concepts of OOPs in Java?
Technical
Q68Why is Java a platform independent language?
Technical
Q69Why is Java not a pure object oriented language?
Technical
Q70What is the difference between Heap and Stack Memory in Java?
Technical
Q71Can Java be said to be the complete object-oriented programming language?
Technical
Q72How is Java different from C++?
Technical
Q73Why does Java not make use of pointers?
Technical
Q74What do you understand by an instance variable and a local variable?
Technical
Q75What is data encapsulation?
Technical
Q76Tell us something about JIT compiler.
Technical
Q77Can you tell the difference between equals() method and equality operator (==) in Java?
Technical
Q78How is an infinite loop declared in Java?
Technical
Q79Briefly explain the concept of constructor overloading.
Technical
Q80Define Copy constructor in Java.
Technical
Q81Can the main method be overloaded?
Technical
Q82Comment on method overloading and overriding by citing relevant examples.
Technical
Q83A single try block and multiple catch blocks can co-exist in a Java Program. Explain.
Technical
Q84Explain the use of final keyword in variable, method and class.
Technical
Q85Do final, finally and finalize keywords have the same function?
Technical
Q86Is it possible that the ‘finally’ block will not be executed? If yes then list the case.
Technical
Q87When can you use super keyword?
Technical
Q88Can the static methods be overloaded?
Technical
Q89Why is the main method static in Java?
Technical
Q90Can the static methods be overridden?
Technical
Q91Difference between static methods, static variables, and static classes in Java.
Technical
Q92What is the main objective of garbage collection?
Technical
Q93What part of memory - Stack or Heap - is cleaned in garbage collection process?
Technical
Q94What are shallow copy and deep copy in Java?
Technical
Q95Although inheritance is a popular OOPs concept, it is less advantageous than composition. Explain.
Technical
Q96What is the difference between ‘>>’ and ‘>>>’ operators in Java?
Technical
Q97What are Composition and Aggregation? State the difference.
Technical
Q98How is the ‘new’ operator different from the ‘newInstance()’ operator in Java?
Technical
Q99What is a deadlock? How can you prevent it?
Technical
Q100What’s the purpose of `volatile`?
Technical
Q101How does `ThreadLocal` work?
Technical
Q102When should you use `Callable` over `Runnable`?
Technical
Q103How is `HashMap` implemented internally?
Technical
Q104What is the difference between `ArrayList` and `LinkedList`?
Technical
Q105When to use `ConcurrentHashMap` vs `Collections.synchronizedMap()`?
Technical
Q106What is fail-fast vs fail-safe iterator?
Technical
Q107How do `TreeMap` and `HashMap` differ?
Technical
Q108What are the four pillars of OOP in Java?
Technical
Q109What is the difference between composition and inheritance?
Technical
Q110What is the Liskov Substitution Principle?
Technical
Q111Can an interface have static methods?
Technical
Q112What is garbage collection in Java?
Technical
Q113Explain the Java memory model.
Technical
Q114What is PermGen vs Metaspace?
Technical
Q115How does G1GC differ from CMS?
Technical
Q116How can you detect and fix memory leaks?
Technical
Q117What is a functional interface?
Technical
Q118Difference between `map()` and `flatMap()` in Streams?
Technical
Q119What are method references?
Technical
Q120What is Optional and how should it be used?
Technical
Q121What is the purpose of default methods in interfaces?
Technical
Q122How does Spring Boot auto-configuration work?
Technical
Q123Difference between `@Component`, `@Service`, `@Repository`?
Technical
Q124How does Spring manage bean lifecycle?
Technical
Q125What is the role of `@ConditionalOnProperty`?
Technical
Q126How do you implement inter-service communication?
Technical
Q127What is the difference between synchronous and asynchronous calls?
Technical
Q128How do you implement retry, fallback, and circuit breaker?
Technical
Q129How do you ensure backward compatibility between services?
Technical
Q130What’s the role of API Gateway in microservice architecture?
Technical
Q131How do you secure REST endpoints?
Technical
Q132What is the difference between OAuth and JWT?
Technical
Q133How do you implement RBAC in Spring Security?
Technical
Q134How do you protect microservices against DDOS or abuse?
Technical
Q135What is rate limiting and how do you implement it?
Technical
Q136What is Spring Cloud Config Server?
Technical
Q137How do you implement distributed tracing?
Technical
Q138How does actuator help in production?
Technical
Q139How to monitor microservices in real time?
Technical
Q140How do you achieve zero-downtime deployment?
Technical
Q141What is blue-green deployment?
Technical
Q142What happens if a service crashes? How do you recover?
Technical
Q143How do you handle data consistency in distributed transactions?
Technical
Q144What is a Saga pattern and when should you use it?
Technical
Q145What is the Singleton pattern? How do you implement it in Java?
Technical
Q146How is Factory pattern different from Abstract Factory?
Technical
Q147What is the Strategy pattern?
Technical
Q148Where is the Builder pattern commonly used?
Technical
Q149What is the Observer pattern?
Technical
Q150Explain the Proxy pattern with real-world usage.
Technical
Q151Difference between Adapter and Decorator pattern?
Technical
Q152What is the Template Method pattern?
Technical
Q153When do you use Command pattern?
Technical
Q154What’s the benefit of Chain of Responsibility?
Technical
Q155What is Dependency Injection? How does Spring use it?
Technical
Q156How is MVC implemented in Spring?
Technical
Q157What is AOP? Common use cases?
Technical
Q158How is Lazy Initialization useful in patterns?
Technical
Q159What’s the difference between Composition and Aggregation?
Technical
Q160Can patterns introduce complexity? How do you balance it?
Technical
Q161What’s the role of the Mediator pattern?
Technical
Q162Example of Flyweight pattern in Java APIs?
Technical
Q163How do you reverse a LinkedList without using extra space?
Technical
Q164Write a function to check if a string is a palindrome.
Technical
Q165What is the time complexity of HashMap operations?
Technical
Q166Explain binary search algorithm.
Technical
Q167How does QuickSort work?
Technical
Q168What’s the difference between BFS and DFS?
Technical
Q169When is a heap used in Java?
Technical
Q170Implement LRU cache.
Technical
Q171What’s a Trie? Use case?
Technical
Q172What is the difference between a stack and a queue?
Technical
Q173How do you detect a cycle in a graph?
Technical
Q174How do you find the intersection of two arrays?
Technical
Q175What’s the difference between Array and LinkedList?
Technical
Q176What is dynamic programming?
Technical
Q177What is memoization?
Technical
Q178Difference between INNER JOIN and LEFT JOIN?
Technical
Q179What is normalization?
Technical
Q180How to prevent SQL Injection in Java?
Technical
Q181What is indexing? How does it work?
Technical
Q182Difference between clustered and non-clustered index?
Technical
Q183What is ACID in databases?
Technical
Q184Explain isolation levels.
Technical
Q185What are transactions and how are they managed in Spring?
Technical
Q186What’s a deadlock in DB?
Technical
Q187How to profile slow queries?
Technical
Q188What’s the use of `JOIN FETCH` in JPQL?
Technical
Q189How do you ensure consistency in distributed DBs?
Technical
Q190What is the difference between optimistic and pessimistic locking?
Technical
Q191When to use NoSQL over RDBMS?
Technical
Q192What’s a primary key vs unique key?
Technical