Just Learn Code

Mastering Data Hiding: Access Modifiers and Accessor Methods Explained

Access Modifiers and Accessor Methods

Have you ever heard of the term “access modifiers” or “accessor methods”? These may sound like complicated programming terms, but they are essential to understanding how to control access to data in object-oriented programming (OOP).

In this article, we’ll be discussing access modifiers and accessor methods, and how they can help you manage scope and protect your data.

Scope control through access modifiers.

Access modifiers in Java are used to restrict access to classes, methods, and variables. There are four types of access modifiers in Java: public, private, protected, and default (also known as package-private).

These access modifiers help control the level of access other code can have to your code. Public access modifier:

This access modifier is the least restrictive, meaning that any code in any package can access the public class, method, or variable.

Public access modifier has a scope that covers the entire project.

Private access modifier:

This access modifier is the most restrictive and is the opposite of the public modifier.

Private variables and methods can only be accessed within the class in which they are declared. Other classes in the same package cannot access them.

Protected access modifier:

This access modifier allows access from within the same package or any derived class outside of the package.

Default/Package private access modifier:

This access modifier is the least restrictive after public, but still more restrictive than protected.

It limits the access to objects to within the same package.

When you define a class, all members (fields, methods, etc.) have a scope that they are accessible within.

When combined with access modifiers, scope can be controlled. For example, you might create two classes in the same package, one of which contains variables or methods that should not be accessed by the other class.

By declaring the variables or methods as private, you restrict access to only the class that contains them.

Accessor methods.

Accessor methods, also referred to as getter functions, are methods used to retrieve the value of a private field in a class. Because private fields cannot be directly accessed outside the class in which they are defined, accessor methods are used to expose (or get) the value of the field.

Getter methods typically have the following syntax:

public get()

For example, let’s say we have a class named Car with several fields. One of the private fields is “model”, and we want to allow access to that field.

We would create a getter, like so:

public String getModel() {

return model;


This method returns the value of the private field “model” when called. It is public, so any other code in the project can access it.

Private fields are used to restrict the access of the fields to only the class that contains them. Getter methods allow us to expose these fields’ values for other classes without allowing them to make changes to those fields.

Additionally , this approach permits applying business logic or validation to the values that are being accessed and returned, which would not be possible to achieve if we just made all variables public.

Mutator Methods

Mutator methods (or setters) are used to both set and validate the private variables a class has. In general, a mutator method is a public method in a class that updates or modifies the value of private instance variables.

A mutator method typically has the following syntax:

public void set( value)

Let us include an example of the Car class we have been discussing, but this time we will include a mutator method for the model field:

public void setModel(String newModel) {

if(newModel.length()>1 && newModel.length() < 10) {

this.model = newModel;



As we can see, the method checks whether the length of the string that is being passed as a parameter is within the set criteria. If the string is between two and ten characters long, it can be assigned to the private model variable.

In other cases, the function returns without making any changes.

In summary

In OOP, access modifiers and accessor methods are essential paradigms when it comes to scope control, data encapsulation, and access. Public, private, and protected access modifiers define the level of access for associated methods or variables.

Private variables are essential when restricting the visibility of the data to others in the class. To access these private variables, we can use accessor methods, which are public methods that provide access to the private data, but while still manipulating the data in their class.

Mutator methods come in handy when we need to set and validate the private variables a class has. By following these principles, we can increase code security and maintainability in our programming projects.

Even when the codebase grows complex, encapsulation, clear naming conventions, and updated access modifiers make the development process smoother. When it comes to Object-Oriented Programming (OOP), data hiding is a vital concept that all programmers must understand.

Essentially, data hiding is the practice of hiding object data that is not relevant to end-users or other classes and modules in the system. In this article, we will explore the importance of data hiding and how accessors and mutators are utilized to achieve it.

Importance of Data Hiding

Data hiding provides a level of security to object data in a program. When sensitive data is not exposed to the world, it prevents any unauthorized access or modification of data by other parts of the code.

By hiding data, developers can be assured that the data’s integrity is maintained throughout the program’s execution. Data hiding also ensures that changes can be made more easily and with fewer consequences.

Suppose one class relies on a second class’s implementation details and accesses its data directly. In that case, any changes made to the second class can impact the first class, making it harder to maintain and debug.

When data is hidden, it enables developers to have better control and consistency over the program’s data access. Only authorized code can access the hidden data, and even that code can only access it via predetermined accessors and mutators.

However, it is important to note that data hiding does not mean that the data cannot be modified at all. Instead, it only allows modification to the data via predetermined developed methods, such as accessors and mutators.

Use of Accessors and Mutators

The use of accessors and mutators is one of the ways to enable the practice of data hiding. Since data hiding restricts access to private data or methods, the use of accessors and mutators makes it possible to get and set values for that data.

Accessors, as mentioned earlier, are public methods that access the private data inside a class, they provide read-only access to the object data, making it accessible without changing the object state.

While accessors do not modify the data, another method called the mutator can modify that data.

Mutators, also called “setters,” provide modification of the private data in the object. They permit internal data changes and ensure that the data is always valid before implementing the changes.

Here is an example of how accessors and mutators can be implemented in a class:

class Student {

private String firstName;

private String lastName;

public String getFirstName() {

return firstName;


public void setFirstName(String firstName) {

if (firstName!= null && firstName.length() > 0) {

this.firstName = firstName;



public String getLastName() {

return lastName;


public void setLastName(String lastName) {

if (lastName!= null && lastName.length()>0) {

this.lastName = lastName;




In the Student class above, the private data members “firstName” and “lastName are only accessible through the public accessors “getFirstName”, “getLastName” and the mutators “setFirstName”, “setLastName.” In these methods, you can apply any validation or filtering that’s needed to ensure that the data is correct and consistently maintainable.

The implementation of accessors and mutators protects the private data from unwanted changes by limiting their access.

It also ensures that the same validation rules apply in every place where the data is being used, leading to fewer errors and enhanced data consistency. In conclusion, data hiding is a programming principle required to guarantee the integrity of an object, enabling developers to control how data is accessed and modified.

A developer who does not implement data hiding exposes code to the risk of unwarranted data access and modifications. By using accessors and mutators, developers can streamline their code’s implementation and have more control over the state of the program.

In Object-Oriented Programming, data hiding is a crucial concept that ensures the data’s integrity is protected by preventing unauthorized access or modifications to sensitive data. By using accessors and mutators, developers can control data access and modification, streamlining their code’s implementation.

Hiding data also enables developers to have better control and consistency over a program’s data access. Ultimately, data hiding improves a program’s security, maintainability, and reliability.

As a final thought, we can say that mastering data hiding is essential for any programmer who wants to create robust and effective object-oriented programs.

Popular Posts