Java
In this tutorial we will learn about member variables of a class in Java programming language.
In the previous tutorial Class Introduction we learned about class. Now lets take about member variables that helps in storing data.
Java classes consists of member variables and methods.
Member variables hold the data whereas, methods of the class operates on the data.
Following are the points to note when naming member variables of a class.
continue
return
In the previous tutorial we created the PackagingBox class. Now we will add the following member variables to hold data that characterise the class representing a real world box.
PackagingBox
And all of the variables will be of data type double.
double
So, our PackagingBox class will now look like the following.
class PackagingBox { // member variables double length; double breadth; double height; double volume; double weight; double price; }
We can use the following access modifiers to control the accessibility of member variables.
If access modifier of a variable is set to public then it can be accessed by code from inside and outside the class.
public
If access modifier of a variable is set to private then it can only be accessed by the code from inside the class.
private
If access modifier of a variable is set to protected then it can be accessed by the code from inside the class. And it can be accessed by the code from child classes that inherits the parent class.
protected
We will learn about inheritance in the later part of this tutorial series.
By default, access modifier of member variables is public.
In the following example we are setting the access modifier of the member variables of the PackagingBox class.
class PackagingBox { // member variables private double length; private double breadth; private double height; public double volume; double weight; double price; }
In the above example we have set the access modifier of length, breadth and height variable to private which means they can be only be accessed from inside the class.
length
breadth
height
We have set the access modifier of volume variable to public this means it can be accessed from both inside and outside the PackagingBox class.
volume
Note! We have not mentioned the access modifier for the weight and price variable so, by default they are set to public.
weight
price
So, far we have learned how to create a class and add member variables and set their access modifier.
In the next tutorial we will learn about methods that will help us to operate on the member variables.
Thanks for reading. See you in the next tutorial :-)