Java provides access modifiers to control the visibility and accessibility of class members. In this blog post, we’ll discuss the differences between four main access modifiers in Java: public, protected, package-private, and private.
Public
The public access modifier is the most permissive of all access modifiers. A class member declared as public can be accessed from anywhere in the code, regardless of the package it is defined in.
public class Example {
public int x;
public void setX(int x) {
this.x = x;
}
}
Protected
The protected access modifier provides more access restrictions than public, but less than package-private or private. A class member declared as protected can be accessed within the same package, as well as in subclasses located in different packages.
class Example {
protected int x;
protected void setX(int x) {
this.x = x;
}
}
Package-private (default)
A class member that does not have any access modifier specified is considered package-private. This means that the member can only be accessed within the same package.
class Example {
int x;
void setX(int x) {
this.x = x;
}
}
Private
The private access modifier is the most restrictive of all access modifiers. A class member declared as private can only be accessed within the same class and is not accessible from any other class, even subclasses.
class Example {
private int x;
private void setX(int x) {
this.x = x;
}
}
Why use access modifiers in Java?
Access modifiers provide a way to encapsulate and protect the data and behavior of a class. By controlling the visibility and accessibility of class members, developers can ensure that the class is used in a safe and predictable way. This helps to prevent unintended modification of class data, which can lead to bugs and security vulnerabilities.
How do access modifiers impact inheritance in Java?
Access modifiers also play a role in inheritance in Java. When a subclass inherits from a superclass, it inherits the class members of the superclass. However, the access level of these members may be restricted based on the access modifier.
For example, if a superclass has a private member, it will not be accessible from the subclass, even though the subclass inherits it. Similarly, if a superclass has a protected member, it will be accessible from the subclass, but not from any other classes outside the package.
Conclusion
In conclusion, when deciding which access modifier to use, consider the visibility and accessibility that is required for the class member. Public is the most permissive, while private is the most restrictive. The protected and package-private access modifiers provide intermediate levels of visibility and accessibility.