So what is an abstraction in OOP programming? Let’s imagine you have a car. it has a lot of characteristics like a weight, dimensions, color, maximum speed etc. To describe a Car object you need only color and max speed for your use-case. Weight and dimensions don’t matter to you. Abstraction means showing only necessary … Read more
Establish a database connection in Java is a common problem. Java provides a JDBC (Java Database Connectivity) API to do that. In this article, I’ll explain what is a JDBC driver, how to create the JDBC connection and execute SQL query. I prepared an example of manual transactions management inside of JDBC connections as well. … Read more
One of the first thing that each beginner programmer should learn is a Java constructor. In this article, I’ll explain what is a constructor in Java (default and parametrized) and different methods how to create a constructor in Java with examples. I’ll show you how to overload constructors and how to access parent class constructor. … Read more
I was really wondered when realized that “Java vs JavaScript” question is really popular! According to Google Keyword Planner Tool, it’s up to 10K searches per month. That means 10K users ask Google about the difference between Java and JavaScript. According to Ahrefs (popular site and keyword analyzing tool), it’s even 15K searches! It’s Google … Read more
First of all, let’s define what is an immutable object in Java. It’s one of the most popular interview questions. An immutable object is an object that constructed once and can’t be changed in future. How to create an immutable class in Java? You should follow rules: Make fields private and final. Make class final … Read more
Beginner programmers often ask what is a transient keyword in Java. Java 9 specification says: Variables may be marked transient to indicate that they are not part of the persistent state of an object. What does it mean? When to use transient variable in java? If you don’t want to serialize (convert an object to … Read more