Java OOP

Java OOP

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1. How to Work With IDE?

Installing Java

Installing IntelliJ IDEA (MacOS)

Installing IntelliJ IDEA (Windows)

Code Editor Main Features

How to do Tasks?

2. OOP

Finally, we can start learning Object-Oriented Programming (OOP) in Java. It will be challenging, but I'm confident that you'll succeed! In this section, we'll cover all the principles of OOP, explain why OOP is important. You'll learn how to inherit classes, overload and override methods, encapsulate data from other classes, and work with abstraction. Moreover, you'll reinforce all these theoretical concepts with practical exercises, working on assignments in your IDE. You'll gain a wealth of knowledge, both practical and theoretical, so let's get started!

OOP Principles: Inheritance

Challenge: Inheritance

OOP Principles: Polymorphism

Challenge: Polymorphism

OOP Principles: Encapsulation

OOP Principles: Abstraction

Challenge: Abstraction

3. Interface

In the previous section, we concluded that all Object-Oriented Programming is mainly built on abstraction. However, an abstract class has one significant limitation – you can inherit from only one abstract class. But what if we need more? Interfaces come to the rescue. In this section, you will learn what an interface is, why it's necessary, how to use it correctly, and you will continue practicing Object-Oriented Programming. Let's turn you into a professional!

What is Interface?

Challenge: Interface

Abstract Class vs Interface

Default Methods

Installing Java

How to install Java?

There are links for downloading Java: MacOS, Windows;
After downloading the file, open it, and you will be greeted by the Java installer. Go through the installer, and you can read the details if you want. After that, the installer will notify you that Java will take up some space on your device. Click the "Install" button with confidence and wait for the installer to finish its work. Congratulations, Java is now installed on your device!

How to check the Java version installed on your device?

Open the terminal on macOS (type terminal in Launchpad search) or open the Developer Command Prompt on Windows (press Win + R and type cmd in the appeared window). Then, enter the command: java -version. As a result, you should see something like this on the console screen:

If the Java version is displayed in the console, it means you have successfully installed it.

What to do if the Java version is not displayed:

Reboot your device and then try entering the command java -version again;
Try entering the command java -help. If the terminal says that such a command does not exist, proceed to the next step;
You will need to reinstall Java using the installer once again. To do this, repeat all the instructions above.

1. How can you check the Java version installed on your device?

2. What should you do if the Java version is not displayed when you run "java -version"?

Everything was clear?

Thanks for your feedback!

Section 1. Chapter 1

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