NTT Data Senior Java Developer Interview Questions, Process, and Tips

Q1. Given an array {1, 2, 1, 4, 5, 4, 8, 7}, how can you use Streams to remove duplicates while retaining only the even numbers?
Ans. 
Use Streams to remove duplicates and retain only even numbers from an array.
• Convert the array to a stream using Arrays.stream()

• Use distinct() to remove duplicates

• Filter out odd numbers using filter()

• Collect the result using collect(Collectors.toList())
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Q2. What is the use of Static and final when you will use Static methods
Ans. 
Static methods can be accessed without creating an instance of the class, while final keyword makes the method unchangeable.
• Static methods belong to the class itself, not to any specific instance

• Final keyword ensures that the method cannot be overridden in subclasses

• Static methods are commonly used for utility methods that do not require access to instance variables

• Example: Math class in Java has static methods like Ma
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Q3. What is the difference between @restController and @controller Annotation
Ans. 
The @RestController annotation is used to define RESTful web services while @Controller annotation is used to define MVC controller.
• RestController is a specialized version of Controller used for RESTful web services

• RestController eliminates the need for @ResponseBody annotation

• Controller is used for traditional MVC controller functionality

• RestController returns data directly without needing to go through a view resolve...read more
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Q4. What is microservices why we use it
Ans. 
Microservices are a software development technique where applications are composed of small, independent services that communicate with each other.
• Microservices allow for easier scalability and maintenance of complex applications.

• Each service in a microservices architecture can be developed, deployed, and scaled independently.

• Microservices promote flexibility and agility in software development.

• Examples of companies us...read more
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The first round was an interview conducted with a GENAI virtual bot.

Q1. Internal architecture of Spring boot, how enable autoconfiguration works
Ans. 
Spring Boot uses autoconfiguration to automatically configure the Spring application based on dependencies and properties.
• Spring Boot autoconfiguration is achieved through @EnableAutoConfiguration annotation

• Autoconfiguration classes are located in the org.springframework.boot.autoconfigure package

• Autoconfiguration classes are conditionally applied based on the presence of specific classes or properties
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Q2. Questions mostly on microservices and coding question on restTemplate
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There were MCQ questions consists of different sections like Design Pattern,Java 8

Q1. Questions related to Multithreading,Design patterns
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Q2. Java coding questions
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Q1. Questions related to Multithreading
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Q2. Java coding questions
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Q1. Java 8, exception handling for method overriding, collections basic on HashMap , hash set, blocking queue. Transient volatile
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Q1. Tell me about your self
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Q2. How garbage collection works in java
Ans. 
Garbage collection in Java is the process of automatically reclaiming memory by destroying unused objects.
• Garbage collection is performed by the JVM to free up memory occupied by objects that are no longer needed.

• It involves identifying and deleting objects that are no longer reachable by any part of the program.

• Java provides automatic garbage collection, so developers do not have to manually manage memory allocation a...read more
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Q3. Difference between String s = "xyz" and String s = new String("xyz")
Ans. 
The first statement creates a string literal in the string pool, while the second statement creates a new string object in the heap memory.
• String s = "xyz" creates a string literal in the string pool.

• String s = new String("xyz") creates a new string object in the heap memory.

• Using String s = new String("xyz") can lead to unnecessary memory usage.
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Q4. Difference between JVM JRE JDK
Ans. 
JVM is the virtual machine that runs Java programs, JRE is the runtime environment for Java programs, and JDK is the development kit for creating Java programs.
• JVM (Java Virtual Machine) is the virtual machine that runs Java bytecode and converts it into machine code.

• JRE (Java Runtime Environment) is the environment in which Java programs are executed. It includes JVM, libraries, and other necessary components.

• JDK (Jav...read more
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Q5. What is public static void main method
Ans. 
The public static void main method is the entry point of a Java program, where execution begins.
• It must be declared as public so that it can be accessed from outside the class.

• It must be declared as static so that it can be called without creating an instance of the class.

• It must have a return type of void, indicating that it does not return any value.

• It takes an array of strings (String[] args) as a parameter, which a...read more
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Q6. Difference between final finally finalize
Ans. 
final is a keyword used to declare constants, finally is a block used in exception handling, and finalize is a method used for cleanup.
• final keyword is used to declare constants that cannot be changed

• finally block is used in exception handling to ensure a piece of code is always executed

• finalize method is used for cleanup operations before an object is garbage collected
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Q7. Internal working of HashSet
Ans. 
HashSet is a collection class in Java that stores unique elements using a hash table.
• Uses hashing to store elements

• Does not maintain insertion order

• Allows null values

• Implements Set interface
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Q8. Hierarchy of ArrayList

Ans. 

ArrayList is a resizable array implementation in Java.

• ArrayList is a class in Java that implements the List interface.

• It allows dynamic resizing of the array, unlike regular arrays.

• Elements can be added, removed, or accessed using index.

• Example: ArrayList names = new ArrayList<>();

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