Access Modifiers in Java: Public, Protected, Default, and Private Explained

Access Modifiers in Java

An access modifier in Java is a keyword used to control the visibility and accessibility of class members such as variables, methods, constructors, and classes.

Access modifiers help achieve data security, encapsulation, and controlled access.

✅ Types of Access Modifiers in Java

Java provides four types of access modifiers:

1. public
2. protected
3. default (no keyword)
4. private

🌍 Real-Life Analogy

Think of a house:

• Public areas → Living room (everyone can access)
• Protected areas → Family room (relatives only)
• Default areas → Inside the house (family members)
• Private areas → Bedroom (only owner)

1. Public Access Modifier
✅ Definition

If a class member is declared as public, it can be accessed:

• Within the same class
• Within the same package
• From a different package

✔ No restriction on access.

public int data;

public void show() {}

🌍 Real-Life Example

Public Park – anyone can enter and use it.

2. Protected Access Modifier
✅ Definition

If a class member is declared as protected, it can be accessed:

• Within the same class
• Within the same package
• In a different package only through inheritance

            protected int value;

            protected void display() {}

🌍 Real-Life Example

Family Property – accessible only to family members (inheritance).

3. Default Access Modifier (Package-Private)
✅ Definition

When no access modifier is specified, it is called default access.

It can be accessed:

• Within the same class
• Within the same package
• ❌ Not accessible outside the package

            int number;

            void print() {}

🌍 Real-Life Example

Apartment Society – only residents can enter.

4. Private Access Modifier

✅ Definition

If a class member is declared as private, it can be accessed:

• Only within the same class

                     private int secret;

                     private void calculate() {}

🌍 Real-Life Example

ATM PIN – known only to the account holder.

🔑 Where Access Modifiers Can Be Used

✅ Public

• Class
• Abstract Class
• Interface
• Static Variable
• Instance Variable
• Static Method
• Instance Method
• Constructor

✅ Protected

• Static Variable
• Instance Variable
• Static Method
• Instance Method
• Constructor

✅ Default

• Class
• Abstract Class
• Interface
• Static Method
• Instance Method
• Constructor
• Static Block
• Instance Block
• Local Variable

✅ Private

• Static Variable
• Instance Variable
• Static Method
• Instance Method
• Constructor

❌ Private classes and interfaces are not allowed

⚠️ Rules of Access Modifiers in Method Overriding
✅ Important Rule

A subclass overriding method cannot reduce visibility, but it can increase visibility.

❌ Invalid Example

class A {

    public void show() {}

}

class B extends A {

    protected void show() {} // ❌ Not allowed

}

✅ Valid Example

class A {

    protected void show() {}

}

class B extends A {

    public void show() {} // ✅ Allowed

}

📌 Key Points to Remember

• Access modifiers control visibility
• public has the highest visibility
• private has the lowest visibility
• Proper use improves security and encapsulation
• Method overriding must not reduce access level