Astrea IT Services Interview Questions and Answers

The main OOPs concepts are encapsulation, inheritance, and polymorphism.

• Encapsulation: bundling of data and methods into a single unit (class) to hide implementation details.

• Inheritance: ability of a class to inherit properties and methods from another class.

• Polymorphism: ability of objects of different classes to be treated as objects of a common superclass.

Polymorphism is the ability of an object to take on many forms. Runtime polymorphism is achieved through method overriding.

• Polymorphism allows objects of different classes to be treated as objects of a common superclass.

• Static polymorphism is achieved through method overloading.

• Runtime polymorphism is determined at runtime based on the actual type of the object.

• Static polymorphism is determined at compile-time based on...read more

The static keyword in Java is used to create variables and methods that belong to the class rather than instances of the class.

• Static variables are stored in the static memory area, also known as the method area or permanent generation.

• Static variables are shared among all instances of a class.

• Static methods can be called without creating an instance of the class.

• Static variables and methods can be accessed using the c...read more

The abstract keyword is used in object-oriented programming to declare a class or method as abstract.

• An abstract class cannot be instantiated and can only be used as a base for other classes.

• An abstract method is a method without a body, and it must be implemented by any concrete subclass.

• Abstract classes can have both abstract and non-abstract methods.

• Abstract methods are used to define a common interface that all sub...read more

Multiple inheritance is when a class inherits from more than one base class. Multilevel inheritance is when a class inherits from another derived class.

• Multiple inheritance allows a class to inherit attributes and behaviors from multiple parent classes.

• Multilevel inheritance involves a chain of inheritance where a derived class inherits from another derived class.

• In multiple inheritance, conflicts may arise if two base...read more

Java implements multiple inheritance through interfaces.

• Java does not support multiple inheritance of classes.

• Instead, it allows multiple inheritance of interfaces.

• A class can implement multiple interfaces, inheriting their methods and constants.

• Interfaces provide a way to achieve multiple inheritance without the complexities of class inheritance.

• Example: class A implements Interface1, Interface2 { ... }

An interface is a contract that defines a set of methods that a class must implement. It is not abstract.

• An interface provides a way to achieve multiple inheritance in Java.

• It allows for loose coupling between classes.

• Interfaces can have constants and default methods.

• A class can implement multiple interfaces.

• Interfaces are used to achieve abstraction and provide a common behavior for classes.

String is immutable because it ensures data integrity and thread safety. StringBuffer and StringBuilder are mutable alternatives.

• String is immutable, meaning its value cannot be changed once created.

• Immutable strings ensure data integrity and thread safety.

• StringBuffer and StringBuilder are mutable alternatives to String.

• StringBuffer is synchronized and thread-safe, but slower.

• StringBuilder is not synchronized, faster,...read more

The optimized solution to print prime numbers between 1 to n.

• Start with a loop from 2 to n

• For each number, check if it is divisible by any number from 2 to its square root

• If it is not divisible by any number, it is a prime number and can be printed

Primary, foreign, and alternate keys are essential for database integrity and relationships between tables.

• Primary Key: Uniquely identifies each record in a table. Example: 'EmployeeID' in an 'Employees' table.

• Foreign Key: A field in one table that links to the primary key of another table. Example: 'DepartmentID' in an 'Employees' table referencing 'Departments'.

• Alternate Key: A candidate key that is not chosen as the...read more

GROUP BY and HAVING clauses are used to aggregate data and filter grouped results in SQL queries.

• GROUP BY is used to group rows that have the same values in specified columns into summary rows.

• HAVING is used to filter records that work on summarized GROUP BY results.

• Example: SELECT department, COUNT(*) FROM employees GROUP BY department; This counts employees per department.

• Example with HAVING: SELECT department, COUNT...read more

I am a recent graduate with a degree in Computer Science and a passion for coding and problem-solving.

• Recent graduate with a degree in Computer Science

• Passionate about coding and problem-solving

• Experience with programming languages like Java, Python, and C++

• Completed internships in software development at XYZ Company

• Strong communication and teamwork skills

I plan to continue learning and growing in my software development career, eventually becoming a senior developer or team lead.

• Continuing to improve my coding skills through online courses and personal projects

• Seeking opportunities for mentorship and learning from experienced developers

• Working towards taking on more responsibility and leadership roles within a development team

I like my college overall, but there are some areas for improvement.

• Good: Excellent faculty members who are knowledgeable and supportive

• Good: Well-equipped labs and facilities for practical learning

• Good: Diverse extracurricular activities and clubs for holistic development

• Bad: Limited internship opportunities for real-world experience

• Bad: Lack of updated curriculum to keep up with industry trends

• Bad: Inadequate career ...read more