Newgen Software Technologies Java Developer Interview Questions and Answers

SQL query to find third highest salary from employee table.

• Use the ORDER BY clause to sort the salaries in descending order

• Use the LIMIT clause to limit the result to the third row

• Use a subquery to exclude the highest and second highest salaries

This program counts the occurrence of each letter in a given string.

• Use a HashMap to store the count of each letter.

• Iterate through the characters of the string and update the count in the HashMap.

• Finally, print the count of each letter.

The default size of an ArrayList is 10.

• The default initial capacity of an ArrayList is 10.

• If the number of elements exceeds the initial capacity, the ArrayList automatically increases its size.

• The capacity of an ArrayList can be increased manually using the ensureCapacity() method.

Servlet life cycle refers to the sequence of events that occur during the lifespan of a servlet.

• Servlet is loaded into memory when the server starts

• init() method is called to initialize the servlet

• service() method is called to handle client requests

• destroy() method is called when the servlet is removed from memory

• Servlet can be reloaded if the server is restarted

Try with resources is a feature introduced in Java 7 to automatically close resources after use.

• It simplifies the code by eliminating the need for a finally block to close the resource

• The resource must implement the AutoCloseable interface

• Multiple resources can be declared in a single try-with-resources statement

• Example: try(FileInputStream fis = new FileInputStream("file.txt")) { //code }

Array is a fixed-size data structure while ArrayList is a dynamic-size data structure in Java.

• Array has a fixed length, while ArrayList can grow dynamically.

• Array can store both primitive types and objects, while ArrayList can only store objects.

• Array uses square brackets [] for declaration, while ArrayList uses angle brackets <>.

• Array provides direct access to elements using index, while ArrayList provides methods for accessing and manipulating elements.

• Example: String[] nam...read more

OOPs concepts are fundamental principles of object-oriented programming that help in designing and implementing software solutions.

• Encapsulation: Bundling data and methods together in a class.

• Inheritance: Creating new classes by inheriting properties and behaviors from existing classes.

• Polymorphism: Ability of an object to take on many forms.

• Abstraction: Hiding complex implementation details and providing a simplified interface.

• Encapsulation, inheritance, and polymorphism tog...read more