Access Modifiers in Java
There are two types of modifiers in Java: access modifiers and non-access modifiers.
The access modifiers in Java specifies the accessibility or scope of a field, method, constructor, or class. We can change the access level of fields, constructors, methods, and class by applying the access modifier on it.
There are four types of Java access modifiers:
There are many non-access modifiers, such as static, abstract, synchronized, native, volatile, transient, etc. Here, we are going to learn the access modifiers only.
Understanding Java Access Modifiers
Let's understand the access modifiers in Java by a simple table.
The private access modifier is accessible only within the class.
Simple example of private access modifier
In this example, we have created two classes A and Simple. A class contains private data member and private method. We are accessing these private members from outside the class, so there is a compile-time error.
Role of Private Constructor
If you make any class constructor private, you cannot create the instance of that class from outside the class. For example:
Note: A class cannot be private or protected except nested class.
If you don't use any modifier, it is treated as default by default. The default modifier is accessible only within package. It cannot be accessed from outside the package. It provides more accessibility than private. But, it is more restrictive than protected, and public.
Example of default access modifier
In this example, we have created two packages pack and mypack. We are accessing the A class from outside its package, since A class is not public, so it cannot be accessed from outside the package.
In the above example, the scope of class A and its method msg() is default so it cannot be accessed from outside the package.
The protected access modifier is accessible within package and outside the package but through inheritance only.
The protected access modifier can be applied on the data member, method and constructor. It can't be applied on the class.
It provides more accessibility than the default modifer.
Example of protected access modifier
In this example, we have created the two packages pack and mypack. The A class of pack package is public, so can be accessed from outside the package. But msg method of this package is declared as protected, so it can be accessed from outside the class only through inheritance.
The public access modifier is accessible everywhere. It has the widest scope among all other modifiers.
Example of public access modifier
Java Access Modifiers with Method Overriding
If you are overriding any method, overridden method (i.e. declared in subclass) must not be more restrictive.
The default modifier is more restrictive than protected. That is why, there is a compile-time error.