Topic 12024 min readStructured Tutorial

Understanding the Protected Access Modifier in Java

Quick Answer

Protected explains in Java, access modifiers control the visibility of classes, methods, and variables.

Learning Objectives

Explain the purpose of Protected in a practical learning context.
Identify the main ideas, terms, and decisions involved in Protected.
Apply Protected in a simple real-world scenario or practice task.

Introduction to Protected Access Modifier

In Java, access modifiers control the visibility of classes, methods, and variables. One important modifier is 'protected'.

The protected keyword allows access to members within the same package and also to subclasses, even if they are in different packages.

Access control is key to encapsulation and secure coding.

What is the Protected Access Modifier?

The protected access modifier is a level of access control in Java that is more permissive than private but more restrictive than public.

It allows members to be accessed by classes in the same package and by subclasses regardless of package.

Accessible within the same package.
Accessible in subclasses even if they are in different packages.
Not accessible by non-subclass classes in different packages.

Protected vs Other Access Modifiers

Java has four main access modifiers: private, default (package-private), protected, and public.

Understanding how protected compares to others helps in choosing the right level of access.

Access Levels Comparison
Access Modifier	Same Class	Same Package	Subclass (Different Package)	Other Packages
private	Yes	No	No	No
default (no modifier)	Yes	Yes	No	No
protected	Yes	Yes	Yes	No
public	Yes	Yes	Yes	Yes

When to Use Protected

Use protected when you want to allow subclasses to access or modify members, but keep them hidden from unrelated classes.

It is useful in inheritance hierarchies where subclasses need to interact with superclass members.

Allow controlled access to class members in inheritance.
Enable package-level access for related classes.
Prevent access from unrelated classes outside the package.

Example of Protected Usage

Here is a simple example demonstrating protected access in Java.

Practical Example

The 'name' field and 'display' method are protected in Animal. Dog subclass can access them even if in the same package. In a different package, direct access to 'name' or 'display' from Test class is not allowed.

Examples

Protected Access Modifier Example

package animals;

public class Animal {
    protected String name;

    protected void display() {
        System.out.println("Animal name: " + name);
    }
}

package animals;

public class Dog extends Animal {
    public void setName(String name) {
        this.name = name; // Accessing protected member
    }

    public void show() {
        display(); // Accessing protected method
    }
}

package test;
import animals.Dog;

public class Test {
    public static void main(String[] args) {
        Dog dog = new Dog();
        dog.setName("Buddy");
        dog.show();
        // dog.name or dog.display() not accessible here directly
    }
}

Best Practices

Use protected to expose members only to subclasses and package classes, not publicly.
Avoid overusing protected to maintain encapsulation and reduce tight coupling.
Document protected members clearly to indicate intended subclass usage.
Prefer private members with protected getters/setters if you want to control access.

Common Mistakes

Assuming protected members are accessible from any class in any package.
Using protected for members that should be private or public instead.
Exposing mutable fields as protected, which can lead to unintended side effects.
Not considering package structure when using protected.

Hands-on Exercise

Experiment with Protected Access

Create a superclass with protected members and two subclasses in different packages. Try accessing the protected members from each subclass and from a non-subclass class.

Expected output: Subclasses can access protected members; non-subclass classes outside the package cannot.

Hint: Remember that protected members are accessible in subclasses regardless of package, but not in unrelated classes outside the package.

Interview Questions

What is the difference between protected and default access modifiers in Java?

Interview

Protected allows access to subclasses even if they are in different packages, while default (package-private) access restricts access only to classes within the same package.

Can a protected member be accessed from a non-subclass in a different package?

Interview

No, protected members cannot be accessed from non-subclass classes outside their package.

What is Protected, and why is it useful?

Beginner

In Java, access modifiers control the visibility of classes, methods, and variables.