Course Content
Java OOP
Java OOP
Packages
Packages in Java
We have already encountered the concept of packages when we were learning about importing different libraries. Packages are the same, but now we will create them ourselves.
I have a class called "Dog
" and a Main
class. Earlier, we created these classes in the same file, but now we can do it nicely. I have split these classes into two different files. One file contains the "Dog
" class, and the other contains the main
class. Also, it's worth noting that the "Dog
" class is located in the "animals" package.
Auto overriding
Here, it is worth reminding about a very useful IntelliJ feature. We can automatically generate various pieces of repetitive code. These could be:
- constructors;
- getters;
- setters;
toString()
methods, and so on.
In our case, we want to generate the toString()
method. To do this, press the appropriate key combination:
- For Mac -
Command + N
; - For Windows -
Alt + Insert
.
This will open a window with options. Choose the code generation option we want using the arrow keys and press Enter. Next, it will prompt us to choose how many fields we want to generate the toString()
method. Choose all fields and click OK.
The toString()
method will be automatically generated and ready to use!
How to import a package?
Let's go back to packages. We have already generated our Dog
class. Now, we need to create an object of this class and call its method in the Main
class. To do this, we need to import the Dog
class from the animals
package, but IntelliJ will do this for us. Next, our task is to create an object of the Dog
class using the constructor:
Great, we have successfully created an object of the Dog
class and printed information about it to the console using the overridden toString()
method.
How to create packages and classes inside
Now, let's understand how to create packages and classes within packages. To do this, we will create a package called birds
inside the animals
package and create a class called Parrot
within it:
- Right-click on the
src
folder and select "Package" from the pop-up list. Enter the name of the package and click "Create":
- Now, with the
birds
package created, we can create a class inside it. Right-click on thebirds
package and select "Class." Give the class a name, in our case,Parrot
, and click "Create":
Note
There's no need to be afraid of the extensive array of features you see when creating something. You won't have to use all of them right away (even I don't use them very often). With experience, you'll become familiar with most of these features, and I'll cover most of them in this course.
Thanks for your feedback!