Logran Technologies Fullstack Java Developer Interview Questions and Answers

General aptitude, logical reasoning, english and Pseudocodes

Q1. Self introduction Project- details, role Programming- Variables, recursion, Features,Arrays, strings, write prime number program.
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Online hackerrank test on Angular and Java

Q1. About project worked on
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Q2. Roles and responsibilities
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Q3. Problems faced in the project
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Q1. Java api calling from angular application and all security and integration related question.
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Q2. Project structure related question
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Q1. Project structure design patterns
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Core Java
DSA
MySQL
Aptitude

Q1. Oops concept one dsa question based on array sql query for filter data LinkedList
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Q1. Just document veriication
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Q1. Tech panel did not show up
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Q1. What is sychronization ?
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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 ?
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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 ?
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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?
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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 ?
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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<Integer> list = new ArrayList<>(); Vector<Integer> vector = new Vector<>();

• Example: list.a...read more
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Q6. What are the legacy classes in java?
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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 ?
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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 ?
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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 ?
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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. 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
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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. Hash map implementation
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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<String, Integer> map = new HashMap<>(); map.put("key", 123); int value = map.get("key");
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