15 Tricky Java Interview Questions| Coforge interview,Persistent Sys 2025 #corejava #hiring

15 Tricky Java Interview Questions| Coforge,Persistent Systems, Infosys 2025 #corejava #hiring Top Core Java Interview Questions with Answers for Freshers - Campus Placement /Job Placement Interview Questions #codingquestions #tcs #ltimindtree #infosys Top 50 Java Interview Questions and Answers | Ace Your Java Programming Interviews #java #interview #JavaInterviewQuestions #TrickyJavaQuestions #CodingInterview #JavaProgramming #SoftwareEngineering #JavaDeveloper #TechJobs Top Core Java Interview Questions || Core Java Interview Questions and Answers [MOST ASKED] Java collections framework interview questions and Answers | MOST ASKED | Core Java | Code Decode Java is pass/call by value or pass/call by reference [MOST IMP. JAVA INTERVIEW QUESTION]| ode Decode This video covers Top Java interview Questions And Answers asked in MNCs from both Freshers and Laterals, Core Java (Java 8 Focus) 1. What are functional interfaces in Java 8? Give some examples. Explain @FunctionalInterface Examples: Runnable, Comparator, custom functional interface 2. What is the difference between HashMap, LinkedHashMap, and TreeMap? Internal implementation Sorting, order, performance 3. Explain the use of Optional in Java 8. How it helps in avoiding NullPointerException Methods: isPresent(), ifPresent(), orElse() 4. What are lambda expressions? How are they useful? Syntax, use cases Integration with streams and collections 5. What are streams in Java 8? How are they different from loops? filter(), map(), collect(), reduce() Parallel streams 🔸 Spring Boot 6. What is the difference between @Component, @Service, @Repository, and @Controller? Roles and Spring stereotype annotations When to use which 7. How does dependency injection work in Spring Boot? Constructor vs field vs setter injection IoC container and bean lifecycle 8. What is Spring Boot Starter and why is it used? Pre-configured dependencies Examples: spring-boot-starter-web, spring-boot-starter-data-jpa 9. How do you handle exceptions in Spring Boot? Using @ControllerAdvice, @ExceptionHandler Global exception handling pattern 10. What are the different ways to create REST APIs in Spring Boot? @RestController, @RequestMapping, @GetMapping, @PostMapping Return types: ResponseEntity, JSON 🔸 Microservices 11. What is the difference between Monolithic and Microservices architecture? Scalability, deployment, modularity Real-life example 12. How do microservices communicate with each other? REST APIs, Feign Client, RabbitMQ, Kafka Synchronous vs asynchronous 13. What is Eureka Server? How does service discovery work in microservices? Registering services Discovery by clients 14. How do you handle configuration management in microservices? Spring Cloud Config Server Externalized config: YAML, properties, Git 15. How do you secure microservices? Use of OAuth2, JWT Role-based access with @PreAuthorize Q) Why String is immutable in java? 1) String pool requires string to be immutable otherwise shared reference can be changed from anywhere. 2) security because string is shared on different area like file system, networking connection, database connection , having immutable string allows you to be secure and safe because no one can change reference of string once it gets created. Q) What is a marker interface? A Marker interface can be defined as the interface having no data member and member functions. In simpler terms, an empty interface is called the Marker interface. Q) Can you override a private or static method in Java? As I have told you in previous videos : method overriding is a good topic to ask trick questions in Java. 1) you can not override a private or static method in Java. 2) you cannot override a private method in sub class because it's not accessible there, what you do is create another private method with the same name in the child class. 3) For static methods if you create a similar method with same return type and same method arguments in child class then it will hide the superclass method, this is known as method hiding. Q) Does “finally” always execute in Java? Not in following cases “System.exit()” function system crash Q) What Methods Does the Object Class Have? Java.lang.Object class, parent of all has following methods : protected Object clone() throws CloneNotSupportedException Creates and returns a copy of this object. public boolean equals(Object obj) Indicates whether some other object is “equal to” this one. protected void finalize() throws Throwable Called by the garbage collector on an object when garbagecollection determines that there are no more references to the object. public final Class getClass() : Returns the runtime class of an object. public int hashCode(): Returns a hash code value for the object. Q) How Can You Make a Class Immutable? Q) What is singleton class in Java and how can we make a class singleton? https://youtu.be/K-gzh9YnunU coforge interview process