Is it possible to instantiate an Abstract class in Java?

Earlier I have shared one of the frequently asked questions in Java, can we make an abstract class final in Java and my readers really liked and asked for more such questions. So, today I am going to talk about whether we can create an instance of an Abstract class in Java or not? This is another interesting core Java question you will find on telephonic interviews or Oracle certified Java programmer certification. The answer to this question is simple, No, you cannot instantiate an abstract class in Java because it is abstract, it is not complete hence it cannot be used.  When you create an instance of a class, its's constructor is called and even though abstract class can have a constructor, the compiler will not allow you to create an instance of the class. It's a compile-time error to create an instance of an abstract class in Java.

How to use Queue in Java - Example Tutorial

The JDK provides implementation of several data structure in Java collection framework e.g. ArrayList is a dynamic array, LinkedList represents a linked list, HashMap represents hash table data structure, and Queue interface represent queue data structure. Btw, If you are not familiar with data structure itself then see Introduction to Data Structures & Algorithms in Java, a good course to start with the essential data structure in Java. The Queue data structure allows you to process elements in the first in first out order and that's why it is also known as FIFO data structure. In order to provide first in first out functionality, it allows you to insert data at one end and delete data from other ends, also known as consuming data. If you need to process objects in the FIFO order you can use a Queue to store them.

Top 4 Free Microsoft SQL Server Books - PDF Download or Online Read

Hello Guys, today, I am going to share some of the good database and SQL server books which are freely available on the internet for reading online or download as PDF. If you have been reading this blog then you know that I love books, I love to read books and I love to collect books that's why I have a big online and offline library. Many people question me do I really find to read all books which I share? Well, I don't read all books page by page, unless and until its something like Effective Java or Clean Code. I mostly skim through books and stopping on interesting and new things, which I don't know or probably have a misconception, but I do like to refer books many times. If I skim through a book, I know where can I find more information about a particular concept and then I explore it in more depth.