Now let us understand the scope of these access modifiers with the help of a table:. 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. 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 private access modifier can be accessed only within the same class and not from outside the class.
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.
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 the class A2 with help of extends keyword 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.
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. 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 class.
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Code inside subclasses cannot access the variable or method, nor can code from any external class. Classes cannot be marked with the private access modifier. Marking a class with the private access modifier would mean that no other class could access it, which means that you could not really use the class at all. Therefore the private access modifier is not allowed for classes.
The member variable time has been marked as private. That means, that the member variable time inside the Clock class cannot be accessed from code outside the Clock class. Fields are often declared private to control the access to them from the outside world. In some cases the fields are truly private, meaning they are only used internally in the class. In other cases the fields can be accessed via accessor methods e. Here is an accessor method example:.
In the above example the two methods getTime and setTime can access the time member variable. The two methods are declared public , meaning they can be called from code anywhere in your application.
The public Java access modifier is covered later in this text. If a constructor in a class is assigned the private Java access modifier, that means that the constructor cannot be called from anywhere outside the class.
A private constructor can still get called from other constructors, or from static methods in the same class. Here is a Java class example illustrating that:.
This version of the Clock class contains a private constructor and a public constructor. The private constructor is called from the public constructor the statement this ;. The private constructor is also called from the static method newClock.
The above example only serves to show you that a private constructor can be called from public constructors and from static methods inside the same class. Do not perceive the above example as an example of clever design in any way.
The default Java access modifier is declared by not writing any access modifier at all. The default access modifier means that code inside the class itself as well as code inside classes in the same package as this class, can access the class, field, constructor or method which the default access modifier is assigned to.
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