Infosys Interview Questions and Answers for Freshers

The exam consists of seven sections, and the cutoff score is quite high; it is essential to complete the exam thoroughly.

Q1. Can you tell me about yourself?
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Q2. Can you provide details about your internship experience?
Ans. 
I completed a 6-month internship at a tech company, where I worked on network infrastructure projects.
• Assisted in setting up and configuring network devices such as routers and switches

• Troubleshooted network issues and implemented solutions

• Collaborated with team members on various IT projects

• Participated in meetings with clients to discuss project requirements
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Q3. Given a puzzle to solve
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Q4. What can you tell me about your major projects?
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I have worked on various major projects including designing and implementing network infrastructure, developing automation scripts, and optimizing system performance.
• Designed and implemented a new network infrastructure for a large company, improving network speed and reliability

• Developed automation scripts to streamline system monitoring and maintenance tasks, saving time and reducing errors

• Optimized system performanc...read more
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Q5. What is the latest news you have heard regarding technology?
Ans. 
The latest news I heard regarding technology is the release of the new iPhone 13 with improved camera features.
• Apple recently announced the release of the iPhone 13 series with upgraded camera capabilities.

• The new iPhone 13 models come with improved low-light performance and cinematic mode for videos.

• Apple also introduced the A15 Bionic chip for enhanced performance and battery life.
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Q1. Why is Java not considered a pure object-oriented programming language?
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Q2. What are the data types supported by Java?
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Java supports two main categories of data types: primitive types and reference types, each serving different purposes.
• Primitive Data Types: These include int, char, double, boolean, etc. Example: int age = 30;

• Reference Data Types: These include objects and arrays. Example: String name = 'John';

• Primitive types are stored directly in memory, while reference types store references to objects.

• Java has 8 primitive data type...read more
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Q3. What is autoboxing and unboxing in Java?
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Q4. What are the default values of all type of variables in java?
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Q5. Apart from Security aspect, What are the reasons that String is immutable in Java?
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Q6. What are the difference between String , StringBuffer and StringBuilder?
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Q7. If a class have multiple main methods with same signature and arguments, then what happens?
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Q8. Is overloading of main methods is possible in java?
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Q9. What is garbage collection in java?
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Q10. When an object is eligible for garbage collection?
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Q11. Explain collection and all of its basic interfaces?
Ans. 
Java Collections Framework provides a set of classes and interfaces for storing and manipulating groups of objects.
• Collection Interface: The root interface for the collection hierarchy. Example: List, Set, Queue.

• List Interface: An ordered collection (also known as a sequence). Example: ArrayList, LinkedList.

• Set Interface: A collection that does not allow duplicate elements. Example: HashSet, TreeSet.

• Queue Interface: A ...read more
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Q12. How HashMap works works internally?
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HashMap stores key-value pairs using a hash table, allowing for efficient data retrieval and storage.
• Uses an array of buckets to store entries.

• Each key is hashed to determine its bucket index.

• Handles collisions using linked lists or trees (Java 8+).

• Resizes when the load factor exceeds a threshold (default 0.75).

• Example: Inserting (key: 'A', value: 1) hashes 'A' to index 0.
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Q13. What is the difference between HashMap and HashTable?
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Q14. What is the difference between HashSet and TreeSet?
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Q15. What is Sterilization in Java?
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Q16. When I want an variable to not participate in Serilization, How can I achieve this?
Ans. 
Use the transient keyword in Java to prevent a variable from being serialized.
• Declare the variable with the transient keyword: `private transient int myVar;`

• Transient variables are ignored during serialization, meaning they won't be saved.

• Useful for sensitive data like passwords or large objects that can be recreated.

• Example: `private transient String password;` will not be serialized.
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Q17. What are the types of Exception in Java?
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Java exceptions are categorized into checked and unchecked exceptions, each serving different error handling purposes.
• Checked Exceptions: Must be declared or handled (e.g., IOException, SQLException).

• Unchecked Exceptions: Do not need to be declared (e.g., NullPointerException, ArrayIndexOutOfBoundsException).

• Errors: Serious issues that applications should not catch (e.g., OutOfMemoryError, StackOverflowError).

• Custom Ex...read more
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Q18. Can we use multiple catch block for a single try block in java?
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Q19. If we have return statement in both try and catch, Which will execute first?
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In Java, if both try and catch have return statements, the catch block's return executes first if an exception occurs.
• The try block executes first; if no exception occurs, its return statement is used.

• If an exception is thrown, the catch block executes, and its return statement takes precedence.

• Example: In a try-catch with return in both, if an exception occurs, the catch's return is returned, ignoring the try's return...read more
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Q20. Can we remove finally block in java?
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Q21. What is Encapsulation in Java?
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Encapsulation in Java is the bundling of data and methods that operate on that data within a single unit, typically a class.
• Encapsulation restricts direct access to some of an object's components, which is a means of preventing unintended interference.

• It is achieved using access modifiers: private, protected, and public.

• Example: A class 'Person' with private fields 'name' and 'age', accessed via public methods.

• Encapsul...read more
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Q22. What is the use of super keyword in java?
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The super keyword in Java is used to refer to the superclass's methods and constructors, enabling access to inherited properties.
• Access superclass methods: super.methodName();

• Access superclass constructors: super();

• Resolve name conflicts: super.variableName;

• Example: class A { void display() { System.out.println('A'); } } class B extends A { void display() { super.display(); System.out.println('B'); } }
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Q23. Can we call a Constructor from another Constructor in Java?
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Yes, constructors can call each other using 'this()' in Java, enabling constructor chaining.
• Constructor chaining allows one constructor to call another within the same class.

• Use 'this(parameters)' to invoke another constructor from a constructor.

• Example: 'this(5)' in a constructor can call another constructor that takes an int parameter.

• Chaining helps reduce code duplication and improves readability.
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Q24. If we have a private static method in Java, Then can we override it? Why and why not?
Ans. 
Private static methods cannot be overridden in Java due to their access level and static nature.
• Private methods are not visible to subclasses, hence cannot be overridden.

• Static methods belong to the class, not instances, preventing polymorphism.

• Example: A private static method in class A cannot be overridden in class B if B extends A.
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Q25. What are Exception rules for inheritance in Java?
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Java's exception inheritance rules dictate how exceptions can be caught and declared in methods.
• 1. Checked exceptions must be declared in the method signature or handled within the method.

• 2. Unchecked exceptions (RuntimeExceptions) do not need to be declared or caught.

• 3. Subclasses of Exception are checked exceptions; subclasses of RuntimeException are unchecked.

• 4. A method can throw multiple exceptions, but must decla...read more
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Q26. What is Servlet?
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Q27. What are JSP filters?
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JSP filters are components that allow developers to intercept requests and responses in JavaServer Pages.
• Filters can modify request and response objects before they reach the JSP or servlet.

• They are defined in the web.xml file or using annotations in Java.

• Common use cases include logging, authentication, and input validation.

• Example: A logging filter can log the details of incoming requests.

• Filters can be chained, allo...read more
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Q28. What are Java Design Patterns?
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Java Design Patterns are reusable solutions to common software design problems, enhancing code maintainability and scalability.
• Creational Patterns: Deal with object creation. Example: Singleton pattern ensures a class has only one instance.

• Structural Patterns: Focus on composition of classes. Example: Adapter pattern allows incompatible interfaces to work together.

• Behavioral Patterns: Concerned with object interaction....read more
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Q29. Explain about current project and your role in the project?
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Q30. Explain about your personal project?
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Q31. What is Spring Framework?
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Q32. What are the Development tools you are using in your project?
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Q33. How many ways we can create threads in Java?
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Q34. Explain about Java memory model?
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They gave a case study where the candidate had to showcase the audience segmentation, create a brochure design with content and showcase the writing skills based on a product that they gave.

Q1. How would you plan a brochure layout?
Ans. 
To plan a brochure layout, consider the target audience, key message, visual hierarchy, branding, and call-to-action.
• Identify the target audience and tailor the design to appeal to their preferences and needs.

• Determine the key message or information that needs to be communicated clearly.

• Establish a visual hierarchy to guide the reader's eye through the content.

• Ensure consistent branding elements such as colors, fonts, ...read more
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Q2. How would you coordinate with stakeholders for information collection?
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I would schedule regular meetings with stakeholders to discuss information needs and establish clear communication channels.
• Schedule regular meetings with stakeholders to discuss information needs

• Establish clear communication channels to ensure timely and accurate information collection

• Utilize project management tools to track progress and deadlines

• Provide stakeholders with updates on information collection process
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Q1. Question on LIST_AGGR
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Q2. Question on dynamic SQL ,what is a bind variable
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Q3. Question on constraints ,do we can delete a child table column having connection with foreign key with parent table
Ans. 
Deleting a child table column linked by a foreign key requires careful consideration of referential integrity.
• Foreign keys enforce referential integrity between parent and child tables.

• You cannot directly delete a column from a child table if it is part of a foreign key constraint.

• To delete the column, first drop the foreign key constraint using: ALTER TABLE child_table DROP CONSTRAINT fk_name;

• After dropping the constr...read more
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Q4. Triggers : do we can use commit or roll back with in trigger ?
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No, we cannot use commit or roll back within a trigger.
• Triggers are automatically committed or rolled back as part of the transaction that fired them.

• Using commit or rollback within a trigger can lead to unpredictable behavior and is not recommended.
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Q5. Materialized views and how to refresh
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Materialized views store the results of a query and can be refreshed to update the data.
• Materialized views store the results of a query in a table-like structure

• They can be refreshed manually or automatically based on a schedule

• Refresh options include full, fast, and force refresh

• Example: CREATE MATERIALIZED VIEW mv_name AS SELECT * FROM table_name;
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Q6. Print 1 to 10 using sql
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Use CONNECT BY LEVEL to print numbers from 1 to 10 in Oracle SQL
• Use CONNECT BY LEVEL to generate rows from 1 to 10

• Select the generated numbers in the query
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Q7. What is Context switching ? And about collection types ...
Ans. 
Context switching is the process of storing and restoring the state of a CPU so that multiple processes can share the same CPU.
• Context switching allows the CPU to switch from one process to another, enabling multitasking.

• In Oracle PLSQL, collection types are used to store multiple values in a single variable.

• Examples of collection types in PLSQL include arrays, nested tables, and associative arrays.
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Q8. Tell me about Analytical functions you worked on ?
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Analytical functions are used to perform calculations across a set of rows related to the current row.
• Analytical functions are used to calculate aggregate values based on a group of rows.

• They can be used to calculate running totals, moving averages, rank, percentiles, etc.

• Examples include functions like ROW_NUMBER(), RANK(), DENSE_RANK(), LAG(), LEAD(), SUM() OVER(), AVG() OVER().
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Q9. What are Set operators ,which one keep duplicates among them
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Set operators are used to combine the result sets of two or more SELECT statements. UNION ALL keeps duplicates.
• Set operators include UNION, UNION ALL, INTERSECT, and MINUS

• UNION ALL retains duplicate rows from the result sets

• Example: SELECT column1 FROM table1 UNION ALL SELECT column1 FROM table2
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