Types of Access specifier or modifiers in Java

In Java, access specifiers (also known as access modifiers) are keywords used to specify the accessibility or visibility of classes, methods, variables, and constructors. These modifiers control how classes and their members can be accessed by other classes and packages. There are four types of access specifiers in Java:

1. public

• Most Accessible: The public modifier allows access from any other class or package.
• Classes, methods, variables, and constructors declared as public can be accessed by any other class.

Example:

public class PublicClass {

    // Class definition

}

public void publicMethod() {

    // Method definition

}

2. protected

• Package and Subclass Access: The protected modifier allows access within the same package and by subclasses (even if they are in different packages).
• It is not applicable to top-level classes.

Example:

protected class ProtectedClass {

    // Class definition

}

protected void protectedMethod() {

    // Method definition

}

3. default (no modifier)

• Package-Private Access: When no access specifier is specified, it is called "default" (package-private).
• Classes, methods, variables, and constructors with default access can only be accessed by classes in the same package.

Example:

class DefaultClass {

    // Class definition

}

void defaultMethod() {

    // Method definition

}

4. private

• Most Restrictive: The private modifier restricts access to only within the same class.
• private members are not accessible from subclasses or from other classes in the same package.

Example:

private class PrivateClass {

    // Class definition

}

private void privateMethod() {

    // Method definition

}

Comparison of Access Modifiers

• public: Most accessible. Can be accessed from any class or package.
• protected: Accessible within the same package and by subclasses (even in different packages).
• default: Accessible only within the same package.
• private: Most restrictive. Accessible only within the same class.

Best Practices

• Encapsulation: Use access modifiers to enforce encapsulation and control access to your classes and members.
• Choose Wisely: Select the appropriate access level for each class member to ensure proper encapsulation and security of your code.

Understanding and correctly applying these access modifiers is crucial for designing Java programs that are both secure and maintainable.