ITCS Java Developer Interview Questions, Process, and Tips

Static block is a block of code that is executed when a class is loaded into memory.

• Static block is declared using the 'static' keyword.

• It is executed only once when the class is loaded.

• It is used to initialize static variables or perform any other static initialization.

• It can throw exceptions which need to be handled.

• Multiple static blocks can be defined in a class and they are executed in the order they are defined.

Method overloading is having multiple methods with the same name but different parameters, while method overriding is having a subclass method with the same name and parameters as a superclass method.

• Method overloading is resolved at compile-time based on the number and type of arguments passed

• Method overriding is resolved at runtime based on the actual object type

• Method overloading is used to provide different ways of...read more

Yes, null value can be added in HashMap.

• HashMap allows null as key and value.

• If a null key is added, it will replace the existing null key.

• If a null value is added, it will be stored as a value with a null key.

Testing is the process of evaluating a system or its component(s) with the intent to find whether it satisfies the specified requirements or not.

• Testing is done to identify defects or errors in the system

• It helps in improving the quality of the system

• Testing can be done at different levels such as unit testing, integration testing, system testing, and acceptance testing

• Automated testing is becoming more popular due to ...read more

Abstract class can have implementation while interface only has method signatures.

• Abstract class can have constructors while interface cannot.

• A class can implement multiple interfaces but can only extend one abstract class.

• Abstract class can have non-abstract methods while interface only has abstract methods.

• Abstract class is used for code reusability while interface is used for polymorphism.

• Example of abstract class: ...read more

Oracle DB is a proprietary RDBMS while SQL DB is a generic term for any RDBMS that uses SQL as its language.

• Oracle DB is developed and marketed by Oracle Corporation while SQL DB is a generic term for any RDBMS that uses SQL as its language.

• Oracle DB is a proprietary RDBMS while SQL DB is a generic term for any RDBMS that uses SQL as its language.

• Oracle DB has its own PL/SQL language while SQL DB uses SQL as its langua...read more

OOPs is a programming paradigm based on the concept of objects.

• Encapsulation - bundling of data and methods that act on that data

• Inheritance - ability of a class to inherit properties and methods from a parent class

• Polymorphism - ability of objects to take on many forms

• Abstraction - hiding of complex implementation details from the user

Abstract is a keyword in Java used to create abstract classes and methods.

• Abstract classes cannot be instantiated

• Abstract methods do not have a body and must be implemented by the subclass

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

• Abstract classes are used to provide a common interface for its subclasses

• Example: abstract class Animal { abstract void makeSound(); }

JSP does not have any implicit methods, but it has implicit objects.

• JSP has implicit objects like request, response, session, application, pageContext, out, config, and exception.

• These objects are automatically available in JSP pages without any declaration or initialization.

• They can be used to perform various operations like accessing request parameters, setting session attributes, etc.

Servlet is an interface in Java EE used to handle HTTP requests and responses.

• Servlet interface is implemented by classes like HttpServlet

• It has methods like init(), service(), and destroy()

• Servlets are used to create dynamic web pages and web applications

I know several frameworks including Spring, Hibernate, and Struts.

• Spring: widely used for building enterprise-level applications

• Hibernate: object-relational mapping framework for database access

• Struts: MVC framework for building web applications