public modifier will break encapsulation property

Question

We always say that, Encapsulation keeps data and functionality safe from the outside world. So its a protective wrapper around the class and the code can be saved from unauthorized access by outer world. But what if, I declare one variable with public modifier will it break Encapsulation ?

That depends. You need to decide what to expose. Usually, don't expose anything related to implementation details. i.e. What does the user of this class _not_ need to know about? — Sweeper, Jan 27 '18 at 08:39
Yes and it considered as a bad practise. https://stackoverflow.com/questions/8002928/public-property-vs-private-property-with-getter — Chaitanya, Jan 27 '18 at 08:47

score 0 · Answer 1 · answered Jan 27 '18 at 08:50

Encapsulation in Java is a mechanism of wrapping the data (variables) and code acting on the data (methods) together as a single unit. In encapsulation, the variables of a class will be hidden from other classes, and can be accessed only through the methods of their current class. Therefore, it is also known as data hiding.

public class EncapTest {
   private String name;
   private String idNum;
   private int age;

   public int getAge() {
      return age;
   }

   public String getName() {
      return name;
   }

   public String getIdNum() {
      return idNum;
   }

   public void setAge( int newAge) {
      age = newAge;
   }

   public void setName(String newName) {
      name = newName;
   }

   public void setIdNum( String newId) {
      idNum = newId;
   }
}

so that all your methods and variable should be private

score 0 · Answer 2 · answered Jan 29 '18 at 09:56

In my idea modifiers absolutely supports Encapsulation. Maybe you just violate Information Hiding.

Encapsulation is not information hiding. Information hiding is a more fundamental technique than encapsulation. We should clarify between Encapsulation and Information Hiding. (see the reference)

Encapsulation is a technique for expressing the boundaries of those modules.

Suppose that we have an attribute in our class and we need to set some values from external the class. We can not define it as public. We can not define it as protected too (see this question), the only way to define this types of conditions is defining some methods (or some modifiers in very simple interface). In this case we Encapsulate it.

So what is the difference between a public attribute and a private attribute with modifiers?

In a very big projects, we can add some other conditions to modifiers without any changes to other parts of project (the OCP of SOLID).

Finally: In some cases we need to set some values from outside the class to attributes. So sometimes we need to use modifiers and it is the encapsulation way to access the fields. We can not define the fields as public or protected in OOP.

score 0 · Answer 3 · answered Jan 31 '19 at 18:14

First of all, let's see what encapsulation really is.

Encapsulation is one of the four OOP concepts. In encapsulation, the variables of a class will be hidden from other classes, and can be accessed only through the methods of their current class. Therefore, it is also known as data hiding.

So making a class variable public it's not encapsulation anymore.

Let's see some real usages of encapsulation:

By encapsulating, you force yourself and other developers to access that variable through their getters and setters. Let's be honest, it's the same thing as if the field was public, right? But what if you add some logic to the setters?

public class User {

    private String username;
    private String password;

    // username getter and setter not displayed in this example.

    public void setPassword(String password) {
        this.password = someCoolHashingMethod(password);
    }

    public String getPassword() {
        return this.password;
    }

}

Do you see what's happening there? You force the password to be stored as a hash instead of clear. (There are many ways to protect a password but we'll stick to this dummy example for now).

Another real use for encapsulation is that you can change the name of the variable without changing the code everywhere in your application.

So you if you change it's name and it's not encapsulated, you will have to go everywhere you used it, modified it, to change there aswell. So a project level refactorization is needed. But if it's encapsulated, you used getters and setters everywhere! That means you just need to change it there only. Example:

public class User {

    private String username;
    private String pass; // <---- notice the new name

    // username getter and setter not displayed in this example.

    public void setPassword(String password) {
        this.pass = someCoolHashingMethod(password); // <---- notice the new name
    }

    public String getPassword() {
        return this.pass; // <---- notice the new name
    }

}

Hope this answered a little bit more than your question really was.

public modifier will break encapsulation property

3 Answers3