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I was interviewed in Jul 2024.
Kafka is a distributed streaming platform used for building real-time data pipelines and streaming applications.
Kafka is designed to handle high-throughput, fault-tolerant, and scalable real-time data streams.
It allows for the publishing and subscribing to streams of records, similar to a message queue.
Kafka is often used for log aggregation, stream processing, event sourcing, and real-time analytics.
It provides featur...
JOINS in MySql are used to combine rows from two or more tables based on a related column between them.
JOINS are used to retrieve data from multiple tables based on a related column
Types of JOINS include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN
Example: SELECT * FROM table1 INNER JOIN table2 ON table1.column = table2.column
I was interviewed in Apr 2024.
I applied via LinkedIn and was interviewed in Oct 2023. There were 3 interview rounds.
1 hr. of the test, 10 questions on core Java concepts, 2 SQL queries, 2 coding question
Sorting strings in an array
Use Arrays.sort() method to sort the array of strings
You can also use a custom Comparator to define the sorting criteria
Remember that sorting is case-sensitive by default
Priority queue can be implemented using an array by maintaining the order of elements based on their priority.
Maintain the order of elements in the array based on their priority level.
When adding elements, insert them in the correct position to maintain the priority order.
When removing elements, remove the element with the highest priority first.
Example: ["High Priority", "Low Priority", "Medium Priority"]
I applied via Walk-in and was interviewed in Jul 2023. There were 4 interview rounds.
There is a hacker rank test for 60 minutes Link provided by the time of 1st round live screen share with hr taking screenshot for govt id proof.
Test has a 8 question in that 5 are mcqs and 2 are coding and 1 is SQL query.
Converts a camel case string to snake case.
Split the string by uppercase letters
Convert each word to lowercase
Join the words with underscores
A Java program using multithreading to print numbers from 1 to 10 in a specific pattern.
Create three threads and assign them to print numbers in a specific pattern
Use synchronization to ensure the correct order of printing
Use a loop to iterate from 1 to 10 and assign the numbers to the threads
Print the thread name and the assigned number in the desired format
To detect a loop in a LinkedList, we can use the Floyd's cycle-finding algorithm.
Initialize two pointers, slow and fast, both pointing to the head of the LinkedList.
Move slow pointer by one step and fast pointer by two steps at a time.
If there is a loop, the slow and fast pointers will eventually meet.
If either of the pointers reaches the end of the LinkedList, there is no loop.
Callable and Runnable are interfaces in Java used for concurrent programming. Callable returns a result and can throw an exception, while Runnable does not return a result or throw an exception.
Callable is a generic interface with a method called 'call()', while Runnable is a functional interface with a method called 'run()'.
Callable can return a result using the 'Future' interface, while Runnable cannot.
Callable can t...
Threads in Java allow concurrent execution of multiple tasks. They can be created in multiple ways.
Using the Thread class
Implementing the Runnable interface
Using the Executor framework
Using the Callable interface with ExecutorService
Wissen Technology interview questions for designations
I was interviewed in Apr 2024.
It was on online platform consists of 7 questions, 2 coding each of 40 marks, 1 SQL query- 20 marks and 4 MCQ's 5 marks each
Get interview-ready with Top Wissen Technology Interview Questions
I applied via Campus Placement and was interviewed in Jan 2024. There were 3 interview rounds.
3 coding ques , basics of oops
3 coding ques , basics of oops
There are two ways to create threads in Java: by extending the Thread class or by implementing the Runnable interface.
Extending the Thread class: Create a new class that extends the Thread class and override the run() method.
Implementing the Runnable interface: Create a new class that implements the Runnable interface and implement the run() method.
Example using Thread class: MyThread extends Thread { public void run()...
I applied via Naukri.com and was interviewed in Feb 2023. There were 3 interview rounds.
Yes, we can keep an object of a Class as a key in HashMap.
The key in a HashMap can be any non-null object.
The key's class must override the hashCode() and equals() methods for proper functioning.
If two objects have the same hashCode(), they will be stored in the same bucket and compared using equals().
If the key is mutable, its state should not be modified after it is used as a key in the HashMap.
If hashcode returns a constant, all elements will be stored in the same bucket, resulting in poor performance.
All elements will be stored in the same bucket of the HashMap.
This will lead to poor performance as the HashMap will essentially become a linked list.
Retrieving elements will take longer as the HashMap will have to iterate through the linked list to find the desired element.
Not overriding equals method can lead to incorrect comparison of objects. Not overriding hashCode method can lead to incorrect behavior in hash-based data structures.
If equals method is not overridden, the default implementation from Object class will be used which compares object references.
This can lead to incorrect comparison of objects where two different objects with same content are considered unequal.
If hashCode...
To make a class immutable, we need to ensure that its state cannot be modified after creation.
Make all fields private and final
Do not provide any setters
Ensure that mutable objects are not returned from methods
Make the class final or use a private constructor
Consider using defensive copying
To handle a mutable object inside an immutable class, make the object private and provide only read-only access methods.
Make the mutable object private to encapsulate it within the immutable class.
Provide read-only access methods to retrieve the state of the mutable object.
Ensure that the mutable object cannot be modified from outside the class.
If necessary, create defensive copies of the mutable object to prevent unin
Immutable classes have advantages like thread safety, security, and simplicity, but also have disadvantages like memory usage and performance overhead.
Advantages of immutable classes:
- Thread safety: Immutable objects can be safely shared among multiple threads without the need for synchronization.
- Security: Immutable objects cannot be modified, which can prevent unauthorized changes to sensitive data.
- Simplicity: Im...
To sort a list of students on the basis of their First name, use the Collections.sort() method with a custom Comparator.
Create a custom Comparator that compares the first names of the students.
Implement the compare() method in the Comparator to compare the first names.
Use the Collections.sort() method to sort the list of students using the custom Comparator.
Object level lock is used to synchronize access to an instance method or block, while class level lock is used to synchronize access to a static method or block.
Object level lock is acquired on a per-object basis, while class level lock is acquired on a per-class basis.
Object level lock is useful when multiple threads are accessing the same instance method or block, while class level lock is useful when multiple thread...
Using Java 8, find the sum of squares of all the odd numbers in the arraylist.
Use the stream() method to convert the ArrayList to a stream
Use the filter() method to filter out the even numbers
Use the mapToInt() method to square each odd number
Use the sum() method to find the sum of the squared odd numbers
The order of execution will be: parent's run() -> child's run() -> parent's walk()
When p.run() is called, it will first execute the run() method of the parent class
Inside the parent's run() method, it will call the walk() method of the parent class
Since the child class overrides the parent class, the child's run() method will be executed next
Inside the child's run() method, it will call the run() method of the parent c...
Serialization is the process of converting an object into a stream of bytes to store or transmit it over a network.
Serialization is used to save the state of an object and recreate it later.
It is also used to send objects over a network as a byte stream.
Java provides Serializable interface to implement serialization.
Serialization can be used for deep cloning of objects.
Example: Saving an object to a file or sending it
Synchronized Map is thread-safe but slower, while Concurrent HashMap is faster but not entirely thread-safe.
Synchronized Map locks the entire map during write operations, causing other threads to wait.
Concurrent HashMap allows multiple threads to read and write simultaneously, using a lock-free approach.
Synchronized Map is useful for small maps or low-concurrency scenarios.
Concurrent HashMap is better suited for large ...
Query to find authors who have written more than 10 books
Use the GROUP BY clause to group the records by author
Use the HAVING clause to filter the groups with a count greater than 10
Join the Bookauthor table with the Author table to get the author names
This program returns the length of the longest word from a string whose length is even.
Split the string into an array of words using a space as the delimiter.
Iterate through the array and check if the length of each word is even.
Keep track of the length of the longest even word encountered.
Return the length of the longest even word.
Answer the salary expectations question in an interview for a Java Developer position.
Research the average salary range for Java Developers in your location and level of experience.
Consider your qualifications, skills, and experience when determining your salary expectations.
Be realistic and flexible in your salary expectations, taking into account the company's budget and industry standards.
Provide a salary range rath...
No location constraints.
I am open to working in any location.
I am willing to relocate if required.
I do not have any personal or family commitments that tie me to a specific location.
Seeking new challenges and growth opportunities.
Looking for a company that aligns better with my career goals.
Seeking a more collaborative and innovative work environment.
Desire to work on larger and more complex projects.
Want to expand my skill set and learn new technologies.
Seeking better work-life balance.
Company restructuring or downsizing.
Limited career advancement opportunities in current company.
I applied via Job Portal and was interviewed in Feb 2024. There was 1 interview round.
I applied via Company Website and was interviewed in Jan 2024. There was 1 interview round.
2 coding questions and 1 sql mcq
I applied via Referral and was interviewed before Feb 2023. There were 2 interview rounds.
Couple of quants and technical mcqs and one coding question.
HashMap is internally implemented using an array of linked lists.
HashMap uses an array to store key-value pairs
Each array index is called a bucket
Each bucket can store multiple key-value pairs using a linked list
Hashing is used to determine the index of the array for a given key
If multiple keys hash to the same index, they are stored in the same bucket
An immutable class is a class whose objects cannot be modified after they are created.
To create an immutable class, make the class final so that it cannot be extended.
Make all the fields private and final, so they cannot be modified.
Do not provide any setter methods, only provide getter methods.
If the class contains mutable objects, make sure to return a copy of the object instead of the original.
Ensure that the class ...
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