Java Access Modifiers

Access Modifiers in Java

Access to variables and methods in Java classes is accomplished through access modifiers. Access modifiers define varying levels of access between class members and the outside world (other objects). Access modifiers are declared immediately before the type of a member variable or the return type of a method.

There are four access modifiers in java :

• default
• public
• protected
• private
  

Access modifiers affect the visibility not only of class members, but also of classes themselves.

Default Access Modifier

The default access modifier specifies that only classes in the same package can have access to a class's variables and methods. Class members with default access have a visibility limited to other classes within the same package. There is no actual keyword for declaring the default access modifier, it is applied by default in the absence of an access modifier.

Code for default access variable and member:

long length;
void getLength() {
return length;
}

Notice that neither the member variable nor the method supplies an access modifier, so each
takes on the default access modifier implicitly.

public Access Modifier

The public access modifier specifies that class variables and methods are accessible to anyone, both inside and outside the class. This means that public class members have global
visibility and can be accessed by any other object.

Sample Code for public member variables:

public int count;
public boolean valid;

protected Access Modifier

The protected access modifier specifies that class members are accessible only to methods in that class and subclasses of that class. This means that protected class members have visibility limited to subclasses.

Sample code for protected variable and a protected method :

protected char Name;
protected char getName() {
return Name;
}

The private Access Modifier

The private access modifier is the most restrictive; it specifies that class members are accessible only by the class in which they are defined. This means that no other class has access to private class members, even subclasses.

Code example for private member variables:

private String firstName;
private double Value;

Access to classes, constructors, methods and fields are regulated using access modifiers. Access modifiers in Java determine the visibility and the scope of the Java elements.