What are access modifiers in Java

💡 Concept: Access Modifiers in Java

Access modifiers define the visibility and accessibility of classes, methods, and variables in Java.

📘 Quick Intro

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

🧠 Analogy

Think of access modifiers as privacy settings on social media, controlling who can see your posts (members).

🔧 Technical Explanation

public: Accessible from anywhere.
private: Accessible only within the class.
protected: Accessible within package and subclasses.
default: Accessible within the package.
Used to enforce encapsulation and hide implementation details.

🎯 Use Cases

✅ Use private to hide internal details.
✅ Use public for API methods.
✅ Use protected to allow subclass access.
✅ Use default for package-level access.

💻 Java Access Modifiers Example


public class Example {
    public int publicVar = 1;
    private int privateVar = 2;
    protected int protectedVar = 3;
    int defaultVar = 4; // package-private

    public void display() {
        System.out.println("Public: " + publicVar);
        System.out.println("Private: " + privateVar);
        System.out.println("Protected: " + protectedVar);
        System.out.println("Default: " + defaultVar);
    }
}

❓ Interview Q&A

Q1: What are the four access modifiers in Java?
A: public, private, protected, default.

Q2: Which modifier is most restrictive?
A: private.

Q3: What is default access?
A: Package-private.

Q4: Can protected members be accessed outside package?
A: Yes, in subclasses.

Q5: Can private members be accessed outside class?
A: No.

Q6: Why use access modifiers?
A: To implement encapsulation.

Q7: Can classes be private?
A: Only nested classes.

Q8: Can interface members be private?
A: Yes, from Java 9.

Q9: What happens if no access modifier is specified?
A: Default (package) access is used.

Q10: What is encapsulation?
A: Hiding internal details using access modifiers.

📝 MCQs

Q1. What are the four access modifiers in Java?

public, private, protected, default
public only
private only
protected only

Q2. Which modifier is most restrictive?

public
private
protected
default

Q3. What is default access?

public
private
Package-private
protected

Q4. Can protected members be accessed outside package?

No
Yes, in subclasses
Only in package
Never

Q5. Can private members be accessed outside class?

Yes
No
Sometimes
Only with reflection

Q6. Why use access modifiers?

To increase visibility
To implement encapsulation
To speed up code
For inheritance

Q7. Can classes be private?

Yes
No
Only nested classes
Only abstract classes

Q8. Can interface members be private?

No
Yes, from Java 9
Only public
Only protected

Q9. What happens if no access modifier is specified?

public
private
Default (package) access
protected

Q10. What is encapsulation?

Exposing all details
Hiding internal details using access modifiers
Inheritance
Polymorphism

💡 Bonus Insight

Proper use of access modifiers is key to maintaining robust, secure, and maintainable Java code.

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