TCS Software Engineer Interview Questions and Answers

Q1. Explain the difference between ArrayList and LinkedList in Java. ArrayList is implemented as a dynamic array, while LinkedList is a doubly linked list. ArrayList provides fast random access (O(1) complexit...read more
Ans. 
ArrayList is preferred for frequent retrieval operations due to fast random access, while LinkedList is suitable for frequent insertions/deletions.
• Use ArrayList when frequent retrieval operations are required, such as searching for elements in a large collection.

• Choose LinkedList when frequent insertions/deletions are needed, like maintaining a queue or stack.

• Consider memory overhead and performance trade-offs when dec...read more
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Q2. What are the advantages and disadvantages of using Java’s synchronized keyword for thread synchronization? The synchronized keyword ensures that only one thread can access a block of code at a time. It pre...read more
Ans. 
ReentrantLock should be used instead of synchronized when more flexibility and control over locking mechanisms is needed.
• Use ReentrantLock when you need to implement custom locking strategies or require advanced features like tryLock() and lockInterruptibly().

• ReentrantLock supports fair locking mechanisms, ensuring that threads acquire the lock in the order they requested it.

• Explicit unlocking in ReentrantLock reduces ...read more
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Q3. What is the difference between == and .equals() in Java? == checks for reference equality, meaning it compares memory addresses. equals() checks for value equality, which can be overridden in user-defined ...read more
Ans. 
In Java, == checks for reference equality while equals() checks for value equality. Misuse of == can lead to logical errors.
• Override equals() when you want to compare the values of objects instead of their references

• Override hashCode() alongside equals() to ensure proper functioning in collections like HashMap

• Consider implementing Comparable interface for natural ordering in collections
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Q4. How does the Java garbage collector work? Garbage collection in Java automatically reclaims memory occupied by unused objects. The JVM has different types of GC algorithms, including Serial, Parallel, CMS,...read more
Ans. 
Garbage collection in Java automatically reclaims memory occupied by unused objects using different algorithms and memory regions.
• Java garbage collector automatically reclaims memory from unused objects

• Different types of GC algorithms in JVM: Serial, Parallel, CMS, G1 GC

• Objects managed in Young Generation, Old Generation, and PermGen/Metaspace

• Minor GC cleans up short-lived objects in Young Generation

• Major GC (Full GC) ...read more
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Q5. What are the main features of Java 8? Java 8 introduced lambda expressions, enabling functional-style programming. The Stream API allows efficient data processing with map, filter, and reduce operations. D...read more
Ans. 
Lambda expressions in Java 8 improve readability and maintainability by enabling concise and functional-style programming.
• Lambda expressions allow writing more compact code by reducing boilerplate code.

• They enable passing behavior as arguments to methods, making code more modular and flexible.

• Example: (a, b) -> a + b is a lambda expression that adds two numbers.
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Q6. Describe the differences between checked and unchecked exceptions in Java. Checked exceptions must be handled using try-catch or declared with throws. Unchecked exceptions (RuntimeException and its subclas...read more
Ans. 
Checked exceptions must be handled explicitly, while unchecked exceptions do not require explicit handling.
• Use custom exceptions when you want to create your own exception types to handle specific scenarios.

• Custom exceptions can be either checked or unchecked, depending on whether you want to enforce handling or not.

• For example, a custom InvalidInputException could be a checked exception if you want to ensure it is cau...read more
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Q7. What is the Java Memory Model, and how does it affect multithreading and synchronization? The Java Memory Model (JMM) defines how threads interact with shared memory. It ensures visibility and ordering of ...read more
Ans. 
The Java Memory Model defines how threads interact with shared memory, ensuring visibility and ordering of variable updates in a concurrent environment.
• Volatile keyword ensures changes to a variable are always visible to all threads.

• Synchronized keyword provides mutual exclusion and visibility guarantees.

• Reordering optimizations by the compiler or CPU can lead to unexpected behavior.

• Happens-before relationship determin...read more
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Q8. Can you explain the difference between method overloading and method overriding in Java? Method overloading allows multiple methods with the same name but different parameters. It occurs within the same cl...read more
Ans. 
Method overloading allows multiple methods with the same name but different parameters, while method overriding allows a subclass to provide a different implementation of a parent method.
• Use method overloading when you want to provide multiple ways to call a method with different parameters.

• Use method overriding when you want to provide a specific implementation of a method in a subclass.

• Example of method overloading: ...read more
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Q9. What are functional interfaces in Java, and how do they work with lambda expressions? A functional interface is an interface with exactly one abstract method. Examples include Runnable, Callable, Predicate...read more
Ans. 
Functional interfaces in Java have exactly one abstract method and work with lambda expressions for concise implementation.
• Functional interfaces have exactly one abstract method, such as Runnable, Callable, Predicate, and Function.

• Lambda expressions provide a concise way to implement functional interfaces.

• Default methods in interfaces help in evolving APIs without breaking backward compatibility.

• Method references (::) ...read more
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Q10. What is a Java Stream, and how does it differ from an Iterator? Streams enable functional-style operations on collections with lazy evaluation. Unlike Iterators, Streams support declarative operations lik...read more
Ans. 
Java Streams enable functional-style operations on collections with lazy evaluation, unlike Iterators.
• Parallel streams can improve performance by utilizing multiple threads, but may introduce overhead due to thread management.

• Care must be taken to ensure thread safety when using parallel streams in a multi-threaded environment.

• Parallel streams are suitable for operations that can be easily parallelized, such as map and...read more
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Q11. Explain the concept of immutability in Java and its advantages. An immutable object cannot be changed after it is created. The String class is immutable, meaning modifications create new objects. Immutabl...read more
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Q12. What is the difference between final, finally, and finalize in Java? final is a keyword used to declare constants, prevent method overriding, or inheritance. finally is a block that executes after a try-c...read more
Ans. 
final, finally, and finalize have different meanings in Java. final is for constants, finally for cleanup, and finalize for garbage collection.
• final is used for constants, preventing method overriding, and inheritance

• finally is used for cleanup actions after a try-catch block

• finalize() is called by the garbage collector before object deletion

• Alternatives to finalize() for resource management include using try-with-reso...read more
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Q13. Explain the Singleton design pattern in Java. Singleton ensures that only one instance of a class exists in the JVM. It is useful for managing shared resources like database connections. A simple implemen...read more
Ans. 
Singleton design pattern ensures only one instance of a class exists in the JVM, useful for managing shared resources like database connections.
• Avoid using Singleton when multiple instances of a class are required.

• Avoid Singleton for classes that are not thread-safe.

• Avoid Singleton for classes that need to be easily mockable for testing purposes.
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Q14. What are Java annotations, and how are they used in frameworks like Spring? Annotations provide metadata to classes, methods, and fields. @Override, @Deprecated, and @SuppressWarnings are common built-in ...read more
Ans. 
Java annotations provide metadata to classes, methods, and fields, improving code readability and maintainability.
• Annotations like @Component, @Service, and @Autowired in Spring help with dependency injection

• Annotations reduce boilerplate code compared to XML configurations

• Custom annotations can be created using @interface

• Reflection APIs allow reading annotation metadata dynamically

• Annotations like @Transactional simpl...read more
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Q15. How do Java Streams handle parallel processing, and what are its pitfalls? Parallel streams divide data into multiple threads for faster processing. The ForkJoin framework handles parallel execution inter...read more
Ans. 
Java Streams handle parallel processing by dividing data into multiple threads using the ForkJoin framework. Pitfalls include race conditions, performance issues with small datasets, and debugging challenges.
• Parallel streams divide data into multiple threads for faster processing

• ForkJoin framework handles parallel execution internally

• Useful for CPU-intensive tasks but may not improve performance for small datasets

• Share...read more
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Q1. Explain the difference between ArrayList and LinkedList in Java. ArrayList is implemented as a dynamic array, while LinkedList is a doubly linked list. ArrayList provides fast random access (O(1) complexit...read more
Ans. 
ArrayList is preferred for frequent retrieval operations due to fast random access, while LinkedList is suitable for frequent insertions/deletions.
• Use ArrayList when frequent retrieval operations are required, such as searching for elements in a large collection.

• Choose LinkedList when frequent insertions/deletions are needed, like maintaining a queue or stack.

• Consider memory overhead and performance trade-offs when dec...read more
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Add your answer
Q2. What are the advantages and disadvantages of using Java’s synchronized keyword for thread synchronization? The synchronized keyword ensures that only one thread can access a block of code at a time. It pre...read more
Ans. 
ReentrantLock should be used instead of synchronized when more flexibility and control over locking mechanisms is needed.
• Use ReentrantLock when you need to implement advanced locking mechanisms such as tryLock() or lockInterruptibly().

• ReentrantLock is preferred when fair locking is required, as it supports fair locking mechanisms.

• Consider using ReentrantLock when you want to avoid potential deadlocks or starvation situ...read more
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Q3. What is the difference between == and .equals() in Java? == checks for reference equality, meaning it compares memory addresses. equals() checks for value equality, which can be overridden in user-defined ...read more
Ans. 
In Java, == checks for reference equality while equals() checks for value equality. Misuse of == can lead to logical errors.
• Override equals() when you want to compare the actual content of objects in user-defined classes.

• Override hashCode() method alongside equals() to ensure proper functioning in collections like HashMap.

• Implement Comparable interface and override compareTo() method for natural ordering of objects.
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Q4. How does the Java garbage collector work? Garbage collection in Java automatically reclaims memory occupied by unused objects. The JVM has different types of GC algorithms, including Serial, Parallel, CMS,...read more
Ans. 
Garbage collection in Java automatically reclaims memory occupied by unused objects using different GC algorithms.
• Force garbage collection in Java using System.gc() or Runtime.gc() methods.

• Not recommended to force garbage collection as it can cause performance issues and disrupt the JVM's natural memory management.

• Forcing garbage collection can lead to unnecessary CPU usage and potential application slowdowns.
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Q5. What are the main features of Java 8? Java 8 introduced lambda expressions, enabling functional-style programming. The Stream API allows efficient data processing with map, filter, and reduce operations. D...read more
Ans. 
Lambda expressions in Java 8 improve readability and maintainability by enabling concise and functional-style programming.
• Lambda expressions allow writing more compact code by reducing boilerplate code.

• They enable passing behavior as arguments to methods, making code more modular and flexible.

• Example: (a, b) -> a + b can be used to define a simple addition operation.

• They promote functional programming paradigms, lea...read more
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Q6. Describe the differences between checked and unchecked exceptions in Java. Checked exceptions must be handled using try-catch or declared with throws. Unchecked exceptions (RuntimeException and its subclas...read more
Ans. 
Checked exceptions must be handled explicitly, while unchecked exceptions do not require explicit handling.
• Custom exceptions should be used to represent specific error conditions in your application.

• Custom exceptions can be either checked or unchecked, depending on whether you want to enforce handling or not.

• Examples of custom checked exceptions could include InvalidInputException or DuplicateRecordException.

• Examples o...read more
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Q7. What is the Java Memory Model, and how does it affect multithreading and synchronization? The Java Memory Model (JMM) defines how threads interact with shared memory. It ensures visibility and ordering of ...read more
Ans. 
The Java Memory Model defines how threads interact with shared memory, ensuring visibility and ordering of variable updates in a concurrent environment.
• Volatile keyword ensures changes to a variable are always visible to all threads.

• Synchronized keyword provides mutual exclusion and visibility guarantees.

• Reordering optimizations by compiler or CPU can lead to unexpected behavior.

• Happens-before relationship determines o...read more
Answered by AI
Add your answer
Q8. Can you explain the difference between method overloading and method overriding in Java? Method overloading allows multiple methods with the same name but different parameters. It occurs within the same cl...read more
Ans. 
Method overloading allows multiple methods with the same name but different parameters, while method overriding allows a subclass to provide a different implementation of a parent method.
• Use method overloading when you want to provide multiple ways to call a method with different parameters.

• Use method overriding when you want to provide a specific implementation of a method in a subclass.

• Example of method overloading: ...read more
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Q9. What are functional interfaces in Java, and how do they work with lambda expressions? A functional interface is an interface with exactly one abstract method. Examples include Runnable, Callable, Predicate...read more
Ans. 
Functional interfaces in Java have exactly one abstract method and work with lambda expressions for concise implementation.
• Functional interfaces have exactly one abstract method, making them suitable for lambda expressions.

• Examples of functional interfaces in Java include Runnable, Callable, Predicate, and Function.

• Default methods in interfaces allow for evolving APIs without breaking backward compatibility.

• Method refe...read more
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Q10. What is a Java Stream, and how does it differ from an Iterator? Streams enable functional-style operations on collections with lazy evaluation. Unlike Iterators, Streams support declarative operations lik...read more
Ans. 
Java Streams enable functional-style operations on collections with lazy evaluation, unlike Iterators.
• Parallel streams can improve performance by utilizing multiple threads, but may introduce overhead due to thread synchronization.

• Care must be taken to ensure thread safety when using parallel streams in a multi-threaded environment.

• Parallel streams are suitable for operations that can be easily parallelized, such as ma...read more
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Add your answer
Q11. Explain the concept of immutability in Java and its advantages. An immutable object cannot be changed after it is created. The String class is immutable, meaning modifications create new objects. Immutabl...read more
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Q12. What is the difference between final, finally, and finalize in Java? final is a keyword used to declare constants, prevent method overriding, or inheritance. finally is a block that executes after a try-c...read more
Ans. 
final, finally, and finalize have different meanings in Java. final is for constants, finally is for cleanup actions, and finalize is for garbage collection.
• final is used to declare constants, prevent method overriding, or inheritance

• finally block executes after try-catch for cleanup actions

• finalize() method is called by garbage collector before object deletion

• Alternatives to finalize() for resource management include ...read more
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Q13. Explain the Singleton design pattern in Java. Singleton ensures that only one instance of a class exists in the JVM. It is useful for managing shared resources like database connections. A simple implemen...read more
Ans. 
Singleton design pattern ensures only one instance of a class exists in the JVM, useful for managing shared resources like database connections.
• Avoid using Singleton when multiple instances of a class are required.

• Avoid Singleton for classes that are not thread-safe.

• Avoid Singleton for classes that need to be easily mockable in unit tests.
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Q14. What are Java annotations, and how are they used in frameworks like Spring? Annotations provide metadata to classes, methods, and fields. @Override, @Deprecated, and @SuppressWarnings are common built-in ...read more
Ans. 
Java annotations provide metadata to classes, methods, and fields, improving readability and maintainability of code.
• Annotations like @Override, @Deprecated, and @SuppressWarnings provide information about the code to developers and tools.

• Frameworks like Spring use annotations such as @Component, @Service, and @Autowired for dependency injection, reducing the need for XML configurations.

• Custom annotations can be create...read more
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Q15. How do Java Streams handle parallel processing, and what are its pitfalls? Parallel streams divide data into multiple threads for faster processing. The ForkJoin framework handles parallel execution inter...read more
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Q1. What's return statement in java
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Q2. What are get set methods
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Q3. What is the difference between an interface and an abstract class in Java?
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Q4. How do you implement a stack in Java using an array?
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Q5. What is the difference between a HashMap and a TreeMap in Java?
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Normal aptitude questions were there you can solve previous year questions to have a greater idea

Q1. Which language I am proficient in?
Ans. 
I am proficient in Java, Python, and C++.
• Java

• Python

• C++
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Q2. About my projects
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