When stepping into the world of Java programming, understanding how to use access modifiers is a key foundational skill. These simple yet powerful tools help you determine who can use or modify different parts of your code, helping to keep your projects organized and secure.
In this blog post, “Access Modifiers in Java: A Simple Guide”, we’ll break down the basics of access modifiers in a straightforward and easy-to-understand manner. Whether you’re just starting out or looking to refresh your knowledge, this guide will help you navigate the different types of access modifiers and how to use them effectively in your Java programs.
Access modifiers are object-oriented programming that is used to set the accessibility of classes, constructors, methods, and other members of Java.
Using the access modifiers we can set the scope or accessibility of these classes, methods, constructors, and other members.
JAVA has two types of modifiers: access modifiers and non-access modifiers.
What are Access Modifiers?
Access modifiers are keywords that can be used to control the visibility of fields, methods, and constructors in a class. The four access modifiers in Java are public, protected, default, and private.
Four Types of Access Modifiers
- Private: We can access the private modifier only within the same class and not from outside the class.
- Default: We can access the default modifier only within the same package and not from outside the package. And also, if we do not specify any access modifier it will automatically consider it as default.
- Protected: We can access the protected modifier within the same package and also from outside the package with the help of the child class. If we do not make the child class, we cannot access it from outside the package. So inheritance is a must for accessing it from outside the package.
- Public: We can access the public modifier from anywhere. We can access public modifiers from within the class as well as from outside the class and also within the package and outside the package.
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Let us see which all members of Java can be assigned with the access modifiers:
| Members of JAVA | Private | Default | Protected | Public |
| Class | No | Yes | No | Yes |
| Variable | Yes | Yes | Yes | Yes |
| Method | Yes | Yes | Yes | Yes |
| Constructor | Yes | Yes | Yes | Yes |
| interface | No | Yes | No | Yes |
| Initializer Block | NOT ALLOWED |
Now let us understand the scope of these access modifiers with the help of a table:
| Accessibility | Private | Default | Protected | Public | |
| Same Package | Same Class | Yes | Yes | Yes | Yes |
| Without Inheritance | No | Yes | Yes | Yes | |
| With Inheritance | No | Yes | Yes | Yes | |
| Different Package | Without Inheritance | No | No | No | Yes |
| With Inheritance | No | No | Yes | Yes |
Let’s understand with more details:
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Private Access Modifier
- The private access modifier is specified when any member of a class is prefixed with the private keyword. In comparison with the other access modifiers, this is the most restricted access modifier.
- When the methods or data members are prefixed with a private access modifier, the visibility of these methods and data members are restricted so, they can be accessed only within the same class where they have been declared, they will not be visible to the outside world.
- If we have another class from the same package still, we will not be able to access these methods or data members. So usually, we keep the class variables and methods as private, which are intended to be used inside the same class where declared.
Let us consider an example where we will consider two classes A1 and A2 within the same package p1. We will declare a variable and a method as private in class A1 and then try to access these methods and variables from class A2.
So here we will Compile Time Error.
Let us see for a private constructor:
If we make any class constructor private, we cannot create the instance of that class from outside the class, and hence, from here we can conclude that the private access modifier can be accessed only within the same class and not from outside the class.
Default Access Modifier
- It is not a keyword. Any Java members such as class or methods or data members when not specified with any access modifier they are by default considered as default access modifiers. These methods or data members are only accessible within the same package and they cannot be accessed from outside the package. It provides more visibility than a private access modifier. But this access modifier is more restricted than protected and public access modifiers.
Let us consider an example for the default access modifier.
Here, we have two different packages p1 and p2. In the p1 package, we have class A1 where we declared a default variable and a default method. Now we are trying to access this variable and method from outside the package that is from package p2 which has a class A2.
When we try to access these variables and methods from outside the package we get a Compile time error.
Hence, we conclude that the default access modifier members can be accessed only within the same package and cannot be accessed from outside the package. And they have more visibility than private access modifier but is more restricted than protected and public access modifiers.
Protected Access Modifier
- It is a keyword. This access modifier is used to access the methods or data members of a class within the same package as well as outside the package but only through inheritance. The protected access modifier has more accessibility than private and defaults access modifiers. But it has less visibility than the public access modifier.
Let us consider an example for a protected access modifier.
Here we have two packages p1 and p2. In package p1 we have class A1 where we have declared a protected test method. In package p2 we are inheriting the members of class A1 inside class A2 with help of extending keywords and creating a relationship between the two classes. We can also say that class A1 is the parent class or the superclass and class A2 is the child class or the subclass respectively.
When we inherit the members of class A1 inside class A2, with the help of a protected access modifier we can access the members of class A1 of package p1 from class A2 of the different package p2.
So here we get the output as Hi I’m from a protected method.
Hence, we can conclude that the methods, variables, and data members of a class prefixed with a protected access modifier can be accessed within the same package as well as can be accessed from outside the package but only with the help of inheritance.
Public Access Modifier
It is a keyword. If a class member like variable, method, or data members are prefixed with a public access modifier, then they can be accessed from anywhere inside the program. That is, they can be accessed within the same class as well as from outside the different classes.
It also includes access within the same package and also from outside the package. The members like variables, methods, and other data members can be accessed globally.
Using public access modifiers we can provide access to the members most simply. There are no restrictions on public access modifier members. Hence, it has the widest accessibility or visibility scope as compared to the rest of the access modifiers.
Let us now consider an example of public access modifier.
Here in this example, we have two different packages p1 and p2. In p1 we have a class a1 where we have declared a variable and a method prefixed public keyword. And in the p2 package, we have a class A2 from where we are trying to access the members of class A1 without inheritance.
Here we get the output as 10 and Hi I’m from the public method.
So from the above example, we can conclude that public access modifier members can be accessed from anywhere, within the same class as well as from outside the class. And also can be accessed within the same package and also from outside a package.
NOTE: If any other developer is using your class, then try to use the most restricted access modifier. And also try to use a private access modifier, wherever necessary.
An overall accessibility:
private<default<protected<public.
JAVA Access Modifiers with Method Overriding
When overriding a method, the method which is overridden should not be restrictive.
For example:
In the above example, the test method is been overridden in class A2. But the subclass method should have the same visibility or more visibility than the superclass method. Since the subclass method has less scope than the superclass method, we get a compile-time error.
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Access Modifier in Java FAQs
Access modifiers in Java are keywords that determine the visibility and accessibility of classes, fields, methods, and constructors in object-oriented programming. They control which parts of a class can be accessed from other classes or packages.
There are four main types of access modifiers in Java:
Public: Allows the class, field, method, or constructor to be accessible from any other class in any package. There are no access restrictions.
Protected: Allows access from the same class, any subclass within the same package, and any subclass in a different package. However, for non-subclasses in different packages, access is restricted.
Default (package-private): If no access modifier is specified, it is considered default. It allows access only within the same package.
Private: Limits access to the same class only. Members marked as private are not accessible from outside the class.
Here are examples of access modifiers in Java:
// Public access modifier
public class PublicClass {
public int publicField;
public void publicMethod() {
// code here
}
}
// Protected access modifier
protected class ProtectedClass {
protected int protectedField;
protected void protectedMethod() {
// code here
}
}
// Default (package-private) access modifier
class DefaultClass {
int defaultField;
void defaultMethod() {
// code here
}
}
// Private access modifier
class PrivateClass {
private int privateField;
private void privateMethod() {
// code here
}
}
An access modifier is a keyword in object-oriented programming languages like Java that defines the scope and visibility of classes, methods, fields, and constructors within a program. It controls how these elements can be accessed from different parts of the program, such as other classes or packages.
Access modifiers in Object-Oriented Programming (OOP) determine the accessibility and visibility of various components of a class. They provide control over the level of encapsulation and interaction between different parts of a program, promoting encapsulation and modular design.
Private: Members marked as private are accessible only within the same class. They are not accessible from outside the class. It provides the highest level of encapsulation.
Protected: Protected members are accessible within the same class, subclasses within the same package, and subclasses in different packages. It provides more accessibility than private but restricts access from unrelated classes.
Public: Public members are accessible from any class in any package. There are no access restrictions. It provides the least encapsulation.
he main difference between protected and private access modifiers is the level of visibility they provide:
Protected: Members with protected access can be accessed within the same class, subclasses within the same package, and subclasses in different packages.
Private: Members with private access can only be accessed within the same class. They are not accessible from subclasses or any other class.
An access specifier is a term used to describe the access level of a class member (field, method, constructor) in object-oriented programming languages. It specifies how the member can be accessed and from where within the program.
