Hexaware Technologies Fullstack Java Developer Interview Questions and Answers

Q1. SQL - a table with emp-id, emp-name, manager-id, Need to find the manger name for each emplyee.
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Q2. FizzBuzz - if number is divisible by 3 print "fizz", if by 5 print "buzz", if by both "fizzbuzz"
Ans. 
A simple program to print 'fizz' for multiples of 3, 'buzz' for multiples of 5, and 'fizzbuzz' for multiples of both.
• Iterate through numbers from 1 to n.

• Use modulo operator to check divisibility by 3 and 5.

• Print 'fizz', 'buzz', or 'fizzbuzz' accordingly.
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Q3. Is it necessary for classes implementing an interface to implement interface methods?
Ans. 
Yes, classes implementing an interface must implement interface methods.
• Classes implementing an interface must provide concrete implementations for all methods declared in the interface.

• Failure to implement all interface methods will result in a compilation error.

• Interfaces are used to define a contract that implementing classes must adhere to.
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Q4. Spring basics - annotations
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Q1. Spring boot basics
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Q1. Talked about my previous companies and salary. Before they conduct the interview I had told them my expectation, while negotiation they denied for providing that and were offering just 10% hike over my cur...read more
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Q1. Q1 - tell me about yourself After my introduction he directly jump into coding and asked me simple array manipulation question. Q3 - balanced string - you have a String = "()()()" or "(()" or "(()). The ou...read more
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Q1. The interviewers don't know how to speak English and are worst in communication. Q1 - Convert int a=123 to string. I told him you can do it with in built method but he asked me to do without it. I told h...read more
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1)Driffience between Abstract class &
Interface.
-abstract class
represents property
&
behaviour of an object
whereas
interface
represents
behaviour
of an object.
2)Driffience between equal() vs ==operator.
equal() is
an object class method
whereas
equal() of string class
override
the object class equal().
3)can we use pointer's in Java.
Not explicitly but implicitly we can use pointer's in java.
Dynamic m/m refers with help of pointer's but java does not support the pointer's.
when we r creating an object in java refrence varaible of an object holds the identity that is nothing but an implicit pointer that holds an unique identity of an object.
4)How we can print object ID.
-Object ID printed with help of object class which is a service provider class having 9().
5)what is object class.
-it is a super class of all predefined & userdefined class.
6)Write a prog to get name of main thread in java.
-class A
{
psvm(String args [])
{
s.o.pln(Thread.currentThread().getName());
}
}
7)length vs length()
-length
is
data menmber
of proxy class
whereas
length() is a string class().

Q1. Explain JVM in ur own language.
Ans. 
JVM is an abstract machine that executes Java bytecode.
• JVM stands for Java Virtual Machine.

• It is responsible for interpreting and executing Java bytecode.

• JVM provides platform independence to Java programs.

• It has its own memory management system and garbage collector.

• JVM can be implemented on different operating systems.

• Examples of JVM languages include Java, Kotlin, and Scala.
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Q2. Exlplaing Multhreading.
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Q1. Question related in resume skills and for company improvement knowledge
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Q2. Personal information
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4 senior interviewer in group discus

Q1. Tell me about yourself?
Ans. •I'm Akashdeep Prasad. • I'm in my early twenties. • I'm born and brought up in Mumbai, Andheri but currently I'm reside in Thane. - Now, coming to my highest qualification :- • I have completed my graduation in Bachelor of Science in Information Technology from University of Mumbai. - I like to share my certification with you :- • I'm certified Java Full Stack Developer. - Sir, I like to share my hobbies with you :...read more
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Q2. Why should I hire you ?
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Q3. What is your salary expectation?
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Q1. I forgot question
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Q1. I can't remember what questions asked
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Q1. Tell you about me self
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Q2. Coding test for me
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Q3. Servlet question
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Q4. Jdbc question and mysql database
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Q5. What is cookie ? why use to create web application
Ans. 
A cookie is a small piece of data stored on the user's computer by the web browser, used to track user activity and personalize user experience.
• Cookies are used to store user preferences, login information, and shopping cart items.

• They help websites remember users and their preferences, making the browsing experience more personalized.

• Cookies can also be used for tracking user behavior, such as analyzing website traffi...read more
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Core java, servlet ,jdbc

Q1. What is sychronization ?
Ans. 
Synchronization is the process of coordinating multiple threads to ensure safe and consistent access to shared resources.
• Synchronization is used to prevent race conditions and ensure thread safety.

• It can be achieved using synchronized blocks or methods.

• Synchronization can cause performance issues if not used properly.

• Example: Synchronizing access to a shared counter variable in a multi-threaded application.
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Q2. What is encapsulation ?
Ans. 
Encapsulation is the process of hiding implementation details and providing access to only necessary information.
• Encapsulation is achieved through access modifiers such as public, private, and protected.

• It helps in achieving data abstraction and information hiding.

• Encapsulation provides better control over the data and prevents unauthorized access.

• Example: A class with private variables and public methods to access the...read more
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Q3. What is interface in java ?
Ans. 
An interface in Java is a collection of abstract methods and constants that can be implemented by a class.
• Interfaces are used to achieve abstraction and provide a way to implement multiple inheritance in Java.

• All methods in an interface are abstract by default and cannot have a body.

• A class can implement multiple interfaces but can only extend one class.

• Interfaces can also have default and static methods with a body.

• Ex...read more
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Q4. What is collection framework?
Ans. 
Collection framework is a set of classes and interfaces that provide a way to store and manipulate groups of objects.
• It provides interfaces like List, Set, Queue, etc. for storing collections of objects.

• It also provides classes like ArrayList, HashSet, PriorityQueue, etc. that implement these interfaces.

• It allows easy manipulation of collections using methods like add, remove, contains, etc.

• It provides algorithms like ...read more
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Q5. What is diffrence between Arraylist and vector ?
Ans. 
ArrayList is not synchronized while Vector is synchronized.
• ArrayList is faster than Vector as it is not synchronized.

• Vector is thread-safe while ArrayList is not.

• Vector is a legacy class while ArrayList is not.

• Vector can grow by a specified amount while ArrayList grows by 50% of its size.

• Example: ArrayList list = new ArrayList<>(); Vector vector = new Vector<>();

• Example: list.add(1); vector.add(1);

• Example: list.get(0);
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Q6. What are the legacy classes in java?
Ans. 
Legacy classes in Java are the classes that have been replaced by newer versions but are still supported for backward compatibility.
• Legacy classes are part of the Java API and are still supported for backward compatibility.

• They have been replaced by newer versions but are still used in older applications.

• Examples of legacy classes include Vector, Hashtable, and Enumeration.

• Legacy classes are not recommended for use in ...read more
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Q7. What is joins in SQL ?
Ans. 
Joins in SQL are used to combine data from two or more tables based on a related column.
• Joins are used to retrieve data from multiple tables in a single query.

• There are different types of joins such as inner join, left join, right join, and full outer join.

• Inner join returns only the matching rows from both tables, left join returns all rows from the left table and matching rows from the right table, right join returns...read more
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Q8. What is autoboxing and auto-unboxing ?
Ans. 
Autoboxing is the automatic conversion of primitive data types to their corresponding object wrapper classes.
• Autoboxing allows primitive data types to be used as objects.

• Auto-unboxing is the reverse process of autoboxing.

• Autoboxing and auto-unboxing are performed automatically by the compiler.

• Example: int i = 10; Integer j = i; // autoboxing

• Example: Integer j = 10; int i = j; // auto-unboxing
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Q9. Difference between where clause and having clause in SQL ?
Ans. 
Where clause filters rows before grouping, having clause filters groups after grouping.
• Where clause is used to filter rows based on a condition before grouping.

• Having clause is used to filter groups based on a condition after grouping.

• Where clause is used with SELECT, UPDATE, DELETE statements.

• Having clause is used with SELECT statement and GROUP BY clause.

• Where clause cannot contain aggregate functions.

• Having clause c...read more
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Q1. Hash map implementation
Ans. 
Hash map is a data structure that stores key-value pairs and allows for fast retrieval of values based on keys.
• Hash map uses hashing to map keys to indices in an array.

• It allows for constant time complexity O(1) for insertion, deletion, and retrieval operations.

• Example: HashMap map = new HashMap<>(); map.put("key", 123); int value = map.get("key");
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