Access Modifiers in java

Access Modifiers in Java

Access to classes is controlled using Access Modifiers aka ( Access Specifiers, Visibility Specifiers) in java. These are used to regulate access to classes, fields and methods in java. Using access modifiers you can control the access of variables, methods with in a class. Java provides number of access modifiers to control the access for class as well as the fields, methods and constructors in your classes.

We have 4 types of access modifiers in java which are explained below:-

Default: Visible to the package, the default. No modifiers are needed, no keyword is required.

Private: Visible to the class only.

Public: Visible to the world.

Protected: Visible to the package and all subclasses.

Default: We do not have any default specifier in Java. It provides Default specifier which is used where no access modifier is present. Using this you can access class, methods or fields which belongs to same package, but not from outside the package. Example

Class demo
{
Int a;
}

Private: Private access modifier is being accessed within the same class to which the methods and fields belong. It is most restrictive access modifier in java. Private access modifiers cannot be accessed outside the class or classes inheriting that class or within subclasses. Which shows that private modifier is just opposite to public access modifier. Using the private modifier is the main way that an object encapsulates itself and hides data from the outside world. Example

Class demo
{
Private int a;
}

Public: It has the widest scope among all other modifiers and having highest level of accessibility. Methods, fields and constructors declared as public within public class are visible to any class, weather these classes are in same package or in any other package. If the public class we are trying to access is in a different package, then the public class still needs to be imported. Example

Class demo
{
public x,y;
public static void main(String[] args){
}
}

The main() method needs to be public to be accessed by java interpreter to run the class.

Protected:  Methods, fields and constructors declared protected in a superclass can be accessed only by subclasses in other packages. Protected access modifier is accessible within same package and outside the package but through inheritance only. Protected access modifier cannot be applied to class and interfaces where as methods, fields can be declared protected, however methods and fields in interface cannot be declared protected. Example

Class demo
{
protected boolean openBook();
}

The following rules for inherited methods are enforced −
·        Methods declared public in a superclass also must be public in all subclasses.
·    Methods declared protected in a superclass must either be protected or public in subclasses; they cannot be private.
·        Methods declared private are not inherited at all, so there is no rule for them.
Access Modifier
within class
within package
outside package by subclass only
Private
Y
N
N
Default
Y
Y
N
Protected
Y
Y
Y
Public
Y
Y
Y
Source of this graph is https://www.javatpoint.com/access-modifiers

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