(New) TCS Java Developer Interview Questions (3 to 5 Years Experience)with Answers

If you’re preparing for a Java Developer interview at TCS (Tata Consultancy Services) with 3 to 5 years of experience, you’ve landed in the right place. This comprehensive guide features commonly asked Java interview questions, covering Core Java, Collections, OOP, Java 8, Spring Boot, SQL, and coding challenges—all with interview-style answers that can help you crack your next interview.

Whether you’re aiming for TCS Digital, TCS Ninja, TCS Innovation Lab, or any Java Developer role, these questions will give you a strong edge.

Core TCS Java Developer Interview Questions

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

Answer:

• An interface can only contain abstract methods (Java 7) or abstract/default/static methods (Java 8+). It supports multiple inheritance.
• An abstract class can contain a mix of abstract and concrete methods, instance variables, and constructors.
• Key difference: Java allows multiple interfaces but only single class inheritance. Use interfaces when you need to define a contract, and abstract classes when you need partial implementation.

2. How do you handle exceptions in Java? (Explain try-catch-finally blocks)

Answer:
Java provides structured exception handling using try-catch-finally.

try {
    int result = 10 / 0;
} catch (ArithmeticException e) {
    System.out.println("Division by zero error");
} finally {
    System.out.println("Cleanup done");
}

• try: Code that may throw an exception.
• catch: Block to handle the exception.
• finally: Code that runs regardless of exception (e.g., closing resources).

3. What is the Java Virtual Machine (JVM)?

Answer:
The JVM is a part of the JRE that interprets compiled Java bytecode and executes it. It enables platform independence (Write Once, Run Anywhere), memory management (GC), and runtime optimisation (JIT).

4. What is the difference between static and non-static methods?

Answer:

• Static method belongs to the class; can be accessed without an instance.
• Non-static method belongs to an instance; needs object creation.

class Demo {
    static void staticMethod() {}
    void nonStaticMethod() {}
}

5. How is inheritance implemented in Java?

Answer:
Java supports single inheritance using the extends keyword.

class Animal {
    void speak() {}
}

class Dog extends Animal {
    void bark() {}
}

It promotes code reuse, method overriding, and polymorphism.

Collections & Data Structures

6. Difference between HashMap and TreeMap in Java

Answer:

Feature	HashMap	TreeMap
Order	No order	Sorted by keys
Null keys	1 null key allowed	No null key
Performance	Faster (O(1))	Slower (O(log n))
Use case	Lookup-heavy	Sorted data

7. Difference between HashMap and Hashtable

Answer:

• HashMap: Not thread-safe, allows null keys/values.
• Hashtable: Thread-safe, no null key or value allowed.

HashMap is preferred for non-synchronised applications.

8. How would you implement a queue in Java using an array?

Answer:

class Queue {
    int front, rear, capacity;
    int[] queue;

    Queue(int size) {
        front = rear = 0;
        capacity = size;
        queue = new int[capacity];
    }

    void enqueue(int item) {
        if (rear == capacity)
            System.out.println("Queue Full");
        else
            queue[rear++] = item;
    }

    void dequeue() {
        if (front == rear)
            System.out.println("Queue Empty");
        else {
            for (int i = 0; i < rear - 1; i++)
                queue[i] = queue[i + 1];
            rear--;
        }
    }
}

OOP Principles & Design

9. What are the main principles of OOP in Java?

Answer:

1. Encapsulation – Data hiding using private variables and public getters/setters.
2. Abstraction – Hiding implementation using interfaces/abstract classes.
3. Inheritance – Code reuse via subclassing.
4. Polymorphism – Multiple forms (overloading, overriding).

10. Explain the concept of inheritance and its advantages.

Answer:
Inheritance allows a class to acquire properties/methods of another class.

Benefits:

• Promotes code reuse
• Enables polymorphism
• Simplifies code maintenance

11. What is object cloning and how is it used in Java?

Answer:
Object cloning means creating a duplicate object using the clone() method.

class Test implements Cloneable {
    int a;
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

Use it for deep copies when object creation is expensive.

12. What are the differences between object-oriented and object-based languages?

Feature	Object-Oriented	Object-Based
Inheritance	Supports	Does not support
Example	Java, C++	JavaScript (partially)
Polymorphism	Fully supported	Limited

Java 8 and New Features

13. What are the main features introduced in Java 8?

Answer:

• Lambda Expressions
• Stream API
• Functional Interfaces
• Default and static methods in interfaces
• Optional class
• Date and Time API

14. Show an example of using the Stream API to filter data.

List<String> names = Arrays.asList("Alice", "Bob", "Alex");
List<String> filtered = names.stream()
    .filter(name -> name.startsWith("A"))
    .collect(Collectors.toList());
System.out.println(filtered); // Output: [Alice, Alex]

15. How is multi-threading handled in Java?

Answer:
Java handles multi-threading using:

• Thread class and Runnable interface
• ExecutorService for thread pools
• synchronized keyword for locking
• High-level APIs like java.util.concurrent

Frameworks and Tools

16. Questions on Spring Boot, Hibernate, and their usage.

Spring Boot:

• Simplifies Spring app setup using auto-configuration.
• Uses embedded servers (Tomcat/Jetty).
• Faster development with @SpringBootApplication.

Hibernate:

• ORM framework for mapping Java classes to DB tables.
• Reduces boilerplate SQL.

17. What is Spring Boot Actuator?

Answer:
Spring Boot Actuator provides production-ready features like:

• Health check endpoints (/actuator/health)
• Metrics monitoring
• Application info
• Integration with Prometheus/Grafana

18. Commonly used design patterns in the Spring ecosystem

Answer:

• Singleton Pattern (beans by default)
• Factory Pattern (ApplicationContext)
• Proxy Pattern (AOP features)
• Template Method (JdbcTemplate, RestTemplate)

SQL & Database

19. Find the highest (or second-highest) salary in an SQL table.

SELECT MAX(salary) 
FROM employees 
WHERE salary < (SELECT MAX(salary) FROM employees);

20. What is the difference between RDBMS and DBMS?

Feature	DBMS	RDBMS
Relationships	No support	Supports relationships
Example	File System	MySQL, Oracle
Normalization	Not required	Required

21. Define a schema in database management.

Answer:
A schema is the structure that defines tables, views, indexes, and relationships in a database. It’s like a blueprint for organising data logically.

Coding & Problem-Solving

22. Write code to implement a binary search in Java.

int binarySearch(int[] arr, int key) {
    int low = 0, high = arr.length - 1;
    while (low <= high) {
        int mid = (low + high) / 2;
        if (arr[mid] == key)
            return mid;
        else if (arr[mid] < key)
            low = mid + 1;
        else
            high = mid - 1;
    }
    return -1;
}

23. Show how to handle multiple exceptions using different catch blocks.

try {
    int a = 5 / 0;
    String s = null;
    System.out.println(s.length());
} catch (ArithmeticException e) {
    System.out.println("Arithmetic error");
} catch (NullPointerException e) {
    System.out.println("Null pointer error");
}

Final Tips for TCS Java Interviews

• Brush up on your data structures, especially maps, lists, and trees.
• Expect scenario-based questions around Spring Boot REST APIs, multi-threading, and JPA.
• SQL is frequently tested; be ready with joins, grouping, and subqueries.
• Practice coding under time pressure using platforms like HackerRank or LeetCode.

Conclusion

This blog covered the top TCS Java developer interview questions targeting professionals with 3 to 5 years of experience. Whether you’re applying for TCS Digital or Core Java roles, these questions and answers will guide your preparation and boost your confidence.

👉 Bookmark this guide and revisit before your next interview.
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