Access modifiers in Java control the visibility and accessibility of classes, methods, and variables. They define who can access a particular entity in the program.

Types of Access Modifiers

There are four types of access modifiers provided in java,

• public
• protected
• private
• default (no modifier)

1. public Access Modifier

• It is accessible from anywhere (inside and outside the class, package, and subclass). 
• It has no restrictions on visibility.

// save into file MyClass.java
package mypackage;
public class MyClass {
   public void showMessage() {
       System.out.println("Public method can be accessed anywhere!");
   }
}

// save into another file Test.java
package anotherpackage;
import mypackage.MyClass;
public class Test {
   public static void main(String[] args) {
       MyClass obj = new MyClass();
       obj.showMessage(); 
   }
}

Output

Public method can be accessed anywhere!

2. private Access Modifier

• It is accessible only within the same class.
• It is not accessible in subclasses or other classes.
• It is used for data hiding.

Example

class Person {
   private String name = "Alice";
   private void display() {
       System.out.println("Name: " + name);
   }
   public static void main(String[] args) {
       Person obj = new Person();
       obj.display(); // Accessible inside the same class
   }
}
class Test {
   public static void main(String[] args) {
       Person obj = new Person();
       // obj.display(); ERROR: Private method not accessible
   }
}

Output (from Person class's main method)

Name: Alice

The display() method cannot be accessed from outside the Person class.

3. protected Access Modifier

• It is accessible within the same package and subclasses outside the package.
• It is used for inheritance.

Example

package mypackage;
class Animal {
   protected void sound() {
       System.out.println("Animals make sounds...");
   }
}
package anotherpackage;
import mypackage.Animal;
class Dog extends Animal {
   public void bark() {
       sound(); // Accessible in subclass
   }
}
public class Test {
   public static void main(String[] args) {
       Dog obj = new Dog();
       obj.bark(); // Accessible through subclass
   }
}

Output

Animals make sounds...

sound() cannot be accessed outside of mypackage unless it is obtained via inheritance.

4. Default Access (No Modifier)

• This is also called package-private access.
• It is accessible only within the same package.
• It is not accessible outside the package (even to subscales).

Example

package mypackage;
class Vehicle {
   void display() {
       System.out.println("This is a vehicle.");
   }
}
package anotherpackage;
import mypackage.Vehicle;
public class Test {
   public static void main(String[] args) {
       Vehicle obj = new Vehicle();
       obj.display(); // ERROR: Cannot access default method outside package
   }
}

The compilation error occurs because display() is not accessible outside of mypackage.

Final thaught

Also, Read: Explain the Constructors in Java