Access Modifiers

Introduction

Access modifiers control the visibility and accessibility of classes, methods, and fields in Java.
They help in encapsulating data and ensuring security and proper access control.

Types of Access Modifiers

1. Public

Scope: Accessible from any other class.
Usage: Used when you want to allow unrestricted access.

Example:

public class Car {
    public int speed;
 
    public void displaySpeed() {
        System.out.println(speed);
    }
}

2. Private

Scope: Accessible only within the same class.
Usage: Used to restrict access and protect data from outside interference.

Example:

public class Car {
    private int speed;
 
    public int getSpeed() {
        return speed;
    }
 
    public void setSpeed(int speed) {
        this.speed = speed;
    }
}

3. Protected

Scope: Accessible within the same package and by subclasses (even if they are in different packages).
Usage: Used when you want to allow access to subclasses but not to other unrelated classes.

Example:

public class Vehicle {
    protected int speed;
 
    protected void displaySpeed() {
        System.out.println(speed);
    }
}
 
public class Car extends Vehicle {
    public void showSpeed() {
        displaySpeed();
    }
}

4. Default (Package-Private)

Scope: Accessible only within the same package.
Usage: Used when you want to restrict access to within the package.
No Keyword: If no access modifier is specified, it defaults to package-private.

Example:

class Car {
    int speed;  // Default access
 
    void displaySpeed() {
        System.out.println(speed);
    }
}

Summary of Access Levels

Modifier	Class	Package	Subclass	World
public	Yes	Yes	Yes	Yes
protected	Yes	Yes	Yes	No
default	Yes	Yes	No	No
private	Yes	No	No	No

Usage Guidelines

public: Use for APIs and classes that need to be accessed from any other class.
private: Use for fields and methods that should not be exposed outside the class. Ideal for internal data and helper methods.
protected: Use for fields and methods that should be accessible in subclasses for extension purposes.
default: Use when you want to restrict access to the package level, ensuring internal package cohesion.

By understanding and correctly applying access modifiers, you can ensure proper encapsulation, data hiding, and maintainable code in Java.

Methods, Fields Setters and Getter methods