# Encapsulation in Java

By

Paul Tomoiu

●

In 

Examples, 

Concepts

●

Published 2022-12-23

In Java OPP (Object-Oriented Programming) we speak about 4 main concepts:

• Abstraction
• Encapsulation
• Inheritance
• Polymorphism

This tutorial explains to you the concept of encapsulation. For a good understanding of the concept you will have an example.

When we speak about Java encapsulation, we speak about hiding data. We don't know how the attributes of a class are defined and used, but we still can modify and see some variables. This is done using getters & setters in Java.

Here is an example:

public class Car {
 
    private String color; 
    private int age;
    private String type;
     
    private String owner;
     
    public String getColor() {
        return color;
    }
    public void setColor(String color) {
        this.color = color;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public String getType() {
        return type;
    }
    public void setType(String type) {
        this.type = type;
    }
}

public class ApplicationMain {

    public static void main(String [] args) {
        Car car = new Car();
        car.setColor("green");
        car.setAge(4);
        car.setType("Peugeot");
 
        System.out.println("This car is "+car.getColor()+".");
        System.out.println("This car has "+car.getAge()+" years old.");
        System.out.println("This car is a "+car.getType()+".");
    }
}

When we run the 'main' class we have the following result:

java ApplicationMain

This car is green.
This car has 4 years old.
This car is a Peugeot.

As you can see in the main class you cannot set directly the variable. The variable could be seen/modified using some methods. For doing this, you have to create "getters" and/or "setters" and to define the class variable as "private".

Somehow related to the encapsulation we have the Java access modifiers. In Java, the access modifiers are used to set the accessibility of variables, methods (including the setter & getter methods), classes, interfaces, constructors.

Here we have the list of access modifiers and their impact: