Intellect Design Arena Java Developer Interview Questions and Answers

Store file data in a database using Java by reading the file, converting it to a suitable format, and executing an SQL insert.

• Read the file using FileInputStream or BufferedReader.

• Convert the file data to a byte array for binary files or String for text files.

• Use JDBC to connect to the database.

• Prepare an SQL statement to insert the data into the appropriate table.

• Execute the statement and handle exceptions.

To find the 3rd highest salary, use SQL queries with subqueries or the DISTINCT keyword.

• Use the DISTINCT keyword to eliminate duplicates: SELECT DISTINCT salary FROM employees ORDER BY salary DESC LIMIT 2, 1;

• Alternatively, use a subquery: SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees));

• Another approach is using ROW_NUMBER...read more

JDBC (Java Database Connectivity) is an API that enables Java applications to interact with databases using SQL.

• JDBC provides a standard interface for connecting to databases.

• It consists of two main packages: java.sql and javax.sql.

• JDBC drivers are required to connect to different databases (e.g., MySQL, Oracle).

• Example of establishing a connection: DriverManager.getConnection(url, user, password).

• JDBC supports ex...read more

Java program to find duplicates in an array of strings

• Create a HashSet to store unique elements

• Iterate through the array and check if element is already in the HashSet

• If element is already in the HashSet, it is a duplicate

To give security to our application, we can implement various measures such as encryption, authentication, authorization, input validation, and regular security audits.

• Implement encryption to protect sensitive data, such as using SSL/TLS for secure communication.

• Use authentication mechanisms like OAuth, JWT, or multi-factor authentication to verify the identity of users.

• Implement authorization to control access to...read more

Method overloading is a feature in Java that allows multiple methods with the same name but different parameters.

• Method overloading is achieved by defining multiple methods with the same name but different parameter types or number of parameters.

• The compiler determines which method to call based on the arguments passed during the method invocation.

• Method overloading improves code readability and reusability.

• Return...read more