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Java Interview Questions in Hyderabad

36 practice questions with answers for Java interviews in Hyderabad.

Java jobs in Hyderabad

Hyderabad has large engineering and capability centres of global technology, banking and pharma companies around HITEC City and the Financial District. Many roles are with global capability centres that work with teams in the US and Europe.

Below are 36 questions that match the mix of service, product and domain employers hiring java developers in Hyderabad.

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01

Map a one-to-many relation between Order and OrderItem in JPA.

JDBC, Hibernate and JPAMedium
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Make the child own the foreign key and keep both sides in sync. @Entity class Order { @Id @GeneratedValue Long id; @OneToMany(mappedBy = "order", cascade = CascadeType.ALL, orphanRemoval = true) List<OrderItem> items = new ArrayList<>(); void addItem(OrderItem i) { items.add(i); i.setOrder(this); } } @Entity class OrderItem { @Id @GeneratedValue Long id; @ManyToOne(fetch = FetchType.LAZY) Order order; }
02

Write a record with validation in its compact constructor.

OOP in JavaMedium
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A compact constructor runs before fields are assigned. public record Money(String currency, long paise) { public Money { Objects.requireNonNull(currency); if (paise < 0) { throw new IllegalArgumentException("negative amount"); } } public Money add(Money o) { return new Money(currency, paise + o.paise); } } Storing money in paise as long avoids floating point errors.
03

Exceptions are being swallowed with empty catch blocks in your codebase. How would you fix this?

Strings and Exception HandlingMedium
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Empty catches hide failures and make production issues invisible. I would find them with static analysis like SonarQube, then decide per case: handle the error properly, rethrow wrapped with context, or at least log with the stack trace. I would add a global exception handler for APIs and a team rule in code review and lint config to block new empty catch blocks.
04

A query is fast in development but takes 8 seconds in production. How do you investigate?

JDBC, Hibernate and JPAMedium
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Production has more data, so check the execution plan with EXPLAIN ANALYZE on production-like data. Look for full table scans, missing indexes on filter or join columns, functions on indexed columns and poor statistics. Check if Hibernate generates the SQL you expect. Add a suitable composite index, rewrite the query or paginate, and verify the plan improves before release.
05

What is Optional and how should it be used?

Java 8+ Features and StreamsMedium
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Optional is a container that may or may not hold a value, used mainly as a method return type to show that a result can be absent, for example findById. Use map, filter, orElse, orElseGet and orElseThrow instead of calling get() blindly. Do not use Optional for fields, parameters or collections, and prefer orElseGet when the default is costly to create.
06

Explain the SOLID principles briefly.

OOP in JavaMedium
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Single Responsibility: a class has one reason to change. Open/Closed: open for extension, closed for modification. Liskov Substitution: subclasses must work wherever the parent is expected. Interface Segregation: prefer small, focused interfaces. Dependency Inversion: depend on abstractions, not concrete classes. Spring dependency injection is a practical example of dependency inversion.
07

Write a sealed interface with records and a switch that computes area.

Java 8+ Features and StreamsMedium
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The switch needs no default because the type set is closed. sealed interface Shape permits Circle, Rect {} record Circle(double r) implements Shape {} record Rect(double w, double h) implements Shape {} static double area(Shape s) { return switch (s) { case Circle c -> Math.PI * c.r() * c.r(); case Rect(double w, double h) -> w * h; }; }
08

What is the role of the JIT compiler?

Java Basics and JVMMedium
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The JVM first interprets bytecode, then profiles which methods run often. The Just In Time compiler converts these hot methods into optimised native code at runtime. HotSpot uses tiered compilation: C1 compiles quickly with light optimisation and C2 applies aggressive optimisations like inlining and escape analysis. This is why Java apps get faster after a warm-up period.
09

How does @Transactional work and what are its common pitfalls?

Spring Boot and MicroservicesHard
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@Transactional is applied through a proxy that opens a transaction before the method and commits or rolls back after. Pitfalls: calling a transactional method from the same class bypasses the proxy, so no transaction starts; by default rollback happens only for unchecked exceptions; it works on public methods; and long transactions with remote calls hold connections. Use propagation and readOnly where suitable.
10

An API listing 100 orders fires 101 SQL queries. How do you fix it?

JDBC, Hibernate and JPAMedium
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This is the N+1 problem from a lazy association loaded in a loop or by JSON serialisation. Fetch what the endpoint needs in one query with JOIN FETCH or @EntityGraph(attributePaths = "items"), or use a DTO projection query. For collections with pagination, fetch ids first, then fetch associations in a second query to avoid in-memory paging. Add a test that asserts the query count.
11

Describe a situation where you had to deliver under a tight deadline.

Multithreading and ConcurrencyMedium
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Situation: a bulk upload feature had to go live in four days for a client launch. Task: build it safely in time. Action: I split it into must-have and later items, used an ExecutorService to process rows in parallel, wrote focused tests for validation and kept the product owner updated daily. Result: we shipped on time, it handled 50,000 rows in under two minutes and we added the extras next sprint.
12

Write a stream to partition numbers into even and odd lists.

Java 8+ Features and StreamsEasy
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partitioningBy splits into a map with true and false keys. Map<Boolean, List<Integer>> parts = nums.stream() .collect(Collectors.partitioningBy(n -> n % 2 == 0)); List<Integer> evens = parts.get(true); List<Integer> odds = parts.get(false); Both keys are always present, even if one list is empty, unlike groupingBy.
13

What is the difference between HashMap, LinkedHashMap and TreeMap?

Collections FrameworkEasy
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HashMap gives O(1) average operations with no ordering guarantee. LinkedHashMap keeps insertion order, or access order if configured, which helps build an LRU cache. TreeMap keeps keys sorted by natural order or a Comparator with O(log n) operations and supports range methods like floorKey and headMap. HashMap allows one null key; TreeMap does not allow null keys with natural ordering.
14

A getter returns an internal List and callers modify it, causing bugs. How do you fix this?

OOP in JavaMedium
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This breaks encapsulation. Return an unmodifiable view with Collections.unmodifiableList(list) or a copy with List.copyOf(list), so callers cannot change internal state. Also copy the list passed into the constructor or setter. If the class should be fully immutable, store List.copyOf in a final field. Expose specific methods like addItem() when controlled changes are needed.
15

Describe a time you had to learn a new technology quickly.

Java 8+ Features and StreamsMedium
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Situation: I joined a project using reactive Spring WebFlux with no prior experience. Task: contribute within two weeks. Action: I studied Project Reactor basics, built a small practice service, paired with a senior on my first ticket and kept notes on common operators. Result: I delivered my first feature in the second week and later wrote the team guide on avoiding blocking calls in reactive code.
16

Write a minimal Dockerfile for a Spring Boot application.

Spring Boot and MicroservicesMedium
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A multi-stage build keeps the image small. FROM eclipse-temurin:21-jdk AS build WORKDIR /app COPY . . RUN ./mvnw -q package -DskipTests FROM eclipse-temurin:21-jre WORKDIR /app COPY --from=build /app/target/*.jar app.jar EXPOSE 8080 ENTRYPOINT ["java", "-XX:MaxRAMPercentage=75", "-jar", "app.jar"] Spring Boot can also build images without a Dockerfile using mvn spring-boot:build-image.
17

Write a Java program to check whether a number is prime.

Java Basics and JVMEasy
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Check divisibility only up to the square root, which makes it O(sqrt n). public static boolean isPrime(int n) { if (n < 2) return false; if (n % 2 == 0) return n == 2; for (int i = 3; (long) i * i <= n; i += 2) { if (n % i == 0) return false; } return true; } The long cast avoids overflow for large n.
18

What is a ClassLoader and what is the delegation model?

Java Basics and JVMMedium
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A ClassLoader loads .class files into the JVM. The main loaders are Bootstrap (core classes), Platform (formerly Extension) and Application (classpath). In the parent delegation model a loader first asks its parent to load a class and only loads it itself if the parent cannot. This prevents user code from replacing core classes like java.lang.String.
19

Describe a time you improved the design of existing code.

OOP in JavaMedium
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Situation: our notification module used a 400 line class with switch cases for email, SMS and WhatsApp. Task: add push notifications without breaking anything. Action: I wrote tests for current behaviour, extracted a Notifier interface with one class per channel and used Spring to inject them by type. Result: push was added in one new class, bugs in that module dropped and new channels now take hours, not days.
20

A @Transactional method is not rolling back after an exception. What could be wrong?

Spring Boot and MicroservicesMedium
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Check that the exception is unchecked, since checked exceptions do not roll back unless rollbackFor is set. Check that the method is called through the Spring proxy, not from another method in the same class. Make sure the method is public and the exception is not caught and swallowed inside. Also confirm the database engine supports transactions and the right transaction manager is used.
21

What is the difference between Comparable and Comparator?

Collections FrameworkEasy
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Comparable defines a class's natural ordering through compareTo() inside the class, such as String sorted alphabetically. Comparator is a separate object with compare(), so you can define many orderings without changing the class. Java 8 made Comparator easy: Comparator.comparing(Employee::getSalary).reversed().thenComparing(Employee::getName). TreeMap and sort methods accept either.
22

Explain the entity lifecycle states in JPA.

JDBC, Hibernate and JPAMedium
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Transient: a new object not yet linked to a persistence context. Managed (persistent): attached to the context, so changes are tracked and flushed automatically through dirty checking. Detached: was managed but the context closed or it was evicted; changes are not tracked until merge(). Removed: scheduled for deletion on flush. persist, merge, detach and remove move entities between these states.
23

What is a deadlock and how can it be prevented?

Multithreading and ConcurrencyMedium
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A deadlock happens when two or more threads each hold a lock and wait for a lock held by the other, so none can continue. It needs mutual exclusion, hold and wait, no preemption and circular wait. Prevent it by always acquiring locks in the same global order, using tryLock with a timeout, holding locks briefly and avoiding calls to unknown code while holding a lock.
24

What is the difference between @Component, @Service, @Repository and @Controller?

Spring Boot and MicroservicesEasy
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All four mark a class as a Spring bean for component scanning. @Service and @Component are functionally the same, with @Service showing business logic intent. @Repository also enables translation of persistence exceptions into Spring DataAccessException. @Controller handles web requests and returns views, and @RestController adds @ResponseBody so return values are written as JSON.
25

What is the difference between lazy and eager loading?

JDBC, Hibernate and JPAMedium
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Lazy loading fetches an association only when it is first accessed, using a proxy; eager loading fetches it immediately with the parent. In JPA, @ManyToOne and @OneToOne default to EAGER, while @OneToMany and @ManyToMany default to LAZY. Best practice is to make all associations lazy and fetch what each use case needs with JOIN FETCH or entity graphs, which avoids loading huge object graphs.
26

How do you mentor junior developers on your team?

Spring Boot and MicroservicesMedium
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Situation: three freshers joined my Spring Boot team at once. Task: make them productive quickly. Action: I created a starter task list, paired with each on their first story, gave detailed but kind code reviews and held a weekly session on topics like transactions and testing. Result: all three shipped features independently within a month and one now mentors new joiners.
27

What is a functional interface?

Java 8+ Features and StreamsEasy
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A functional interface has exactly one abstract method, so it can be implemented with a lambda or method reference. It may also have default and static methods. Examples are Runnable, Comparator, and those in java.util.function: Function, Predicate, Consumer, Supplier and BiFunction. The @FunctionalInterface annotation makes the compiler enforce the single abstract method rule.
28

A stream over a list of orders is slow in a hot path. How do you analyse it?

Java 8+ Features and StreamsHard
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Profile first with JFR or async-profiler to confirm the stream is the hotspot. Check for repeated work like calling sorted() inside a loop, boxing overhead with Stream of Integer instead of IntStream, or re-streaming the same list many times. Cache computed maps, use primitive streams and, if still slow, a plain loop can be clearer and faster for very hot code.
29

How does JWT based authentication work in a Spring Boot API?

Spring Boot and MicroservicesHard
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After login, the auth server issues a signed JWT with claims like user id, roles and expiry. The client sends it in the Authorization: Bearer header. The API, configured as an OAuth2 resource server in Spring Security, verifies the signature with the public key, checks expiry and builds the security context, so no session is needed. Keep tokens short-lived and use refresh tokens for renewal.
30

Explain bean scopes in Spring.

Spring Boot and MicroservicesMedium
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singleton is the default: one instance per application context. prototype creates a new instance each time it is requested. Web scopes include request, session and application. Singletons must be stateless or thread safe because all requests share them. Injecting a prototype into a singleton gives only one instance, so use ObjectProvider or a scoped proxy to get fresh ones.
31

Use CountDownLatch to wait for three worker threads to finish.

Multithreading and ConcurrencyMedium
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The main thread waits until the count reaches zero. CountDownLatch latch = new CountDownLatch(3); for (int i = 0; i < 3; i++) { new Thread(() -> { try { doWork(); } finally { latch.countDown(); } }).start(); } latch.await(30, TimeUnit.SECONDS); System.out.println("all done"); countDown in finally makes sure the latch is released even on error.
32

What is exception chaining?

Strings and Exception HandlingMedium
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Exception chaining wraps a low level exception in a higher level one while keeping the original as the cause, for example throw new OrderException("save failed", sqlEx). The full stack trace shows both, with Caused by lines. It lets each layer speak its own language without losing the root cause, which is essential when debugging production logs.
33

How does Spring Boot auto-configuration work?

Spring Boot and MicroservicesMedium
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At startup Spring Boot reads auto-configuration classes listed in META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports. Each class uses conditions like @ConditionalOnClass, @ConditionalOnMissingBean and @ConditionalOnProperty, so it creates beans only when the library is on the classpath and you have not defined your own. Run with --debug to see the condition report showing what was applied and why.
34

Find the first non-repeating character in a string.

Strings and Exception HandlingMedium
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Count in one pass, then scan again in order. public static char firstUnique(String s) { int[] cnt = new int[128]; for (char c : s.toCharArray()) cnt[c]++; for (char c : s.toCharArray()) { if (cnt[c] == 1) return c; } return '_'; } Two passes, O(n) time and O(1) extra space for ASCII input.
35

What is the difference between an abstract class and an interface in modern Java?

OOP in JavaMedium
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An abstract class can have state (instance fields), constructors and any access modifier, and a class can extend only one. An interface has no instance state but, since Java 8, can have default and static methods, and since Java 9 private methods; a class can implement many. Use an interface for a capability contract and an abstract class to share code and state among closely related classes.
36

Run two tasks in parallel with CompletableFuture and combine their results.

Multithreading and ConcurrencyMedium
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Use a dedicated executor for I/O work. ExecutorService pool = Executors.newFixedThreadPool(4); CompletableFuture<User> user = CompletableFuture.supplyAsync(() -> userApi.get(id), pool); CompletableFuture<List<Order>> orders = CompletableFuture.supplyAsync(() -> orderApi.list(id), pool); Profile p = user.thenCombine(orders, Profile::new) .orTimeout(2, TimeUnit.SECONDS) .join();

Companies with offices in Hyderabad (14)

IT services

TCS

Java interview questions

  • 30 questions
  • 4 rounds

Mumbai, Chennai, Pune +2

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IT services

Infosys

Java interview questions

  • 30 questions
  • 4 rounds

Bengaluru, Mysuru, Pune +2

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IT services

Wipro

Java interview questions

  • 30 questions
  • 4 rounds

Bengaluru, Hyderabad, Pune +2

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Consulting

Accenture

Java interview questions

  • 30 questions
  • 4 rounds

Bengaluru, Hyderabad, Pune +2

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IT services

Cognizant

Java interview questions

  • 30 questions
  • 4 rounds

Chennai, Bengaluru, Pune +2

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IT services

Capgemini

Java interview questions

  • 30 questions
  • 4 rounds

Mumbai, Bengaluru, Pune +2

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IT services

HCLTech

Java interview questions

  • 30 questions
  • 4 rounds

Noida, Chennai, Bengaluru +2

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IT services

Tech Mahindra

Java interview questions

  • 30 questions
  • 4 rounds

Pune, Hyderabad, Bengaluru +2

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IT services

LTIMindtree

Java interview questions

  • 30 questions
  • 4 rounds

Mumbai, Pune, Bengaluru +2

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Product

Amazon

Java interview questions

  • 30 questions
  • 5 rounds

Bengaluru, Hyderabad, Chennai +2

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Product

Oracle

Java interview questions

  • 30 questions
  • 5 rounds

Bengaluru, Hyderabad, Noida +2

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Banking & finance

Goldman Sachs

Java interview questions

  • 30 questions
  • 5 rounds

Bengaluru, Hyderabad, Mumbai

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Banking & finance

JP Morgan Chase

Java interview questions

  • 30 questions
  • 5 rounds

Mumbai, Bengaluru, Hyderabad

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E-commerce & consumer tech

Flipkart

Java interview questions

  • 30 questions
  • 5 rounds

Bengaluru, Hyderabad

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Frequently asked questions

Which companies hire Java professionals in Hyderabad?

Companies with large offices in Hyderabad include TCS, Infosys, Wipro, Accenture, Cognizant, Capgemini, HCLTech, Tech Mahindra, LTIMindtree, Amazon. Use their company pages below to practise employer-specific sets.

Are Java interviews in Hyderabad different from other cities?

The questions depend more on the company than the city. Hyderabad's mix of employers decides the style: Many roles are with global capability centres that work with teams in the US and Europe

How do I find Java jobs in Hyderabad?

Shortlist companies with Hyderabad offices, keep your CV focused on Java projects, apply on company career pages and job portals with the Hyderabad filter, and practise the questions on this page before each interview.

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