Whenever we are writing our classes, we have to provide some information about our classes to the JVM like whether this class can be accessed from anywhere or not, whether child class creation is possible or not, whether object creation is possible or not, etc. we can specify this information by using an appropriate keyword in java called access modifiers. So access modifiers are used to set accessibility of classes, methods, and other members.
Public Access Modifiers: If a class is declared as public then we can access that class from anywhere.
In the below example we are creating a package pack1 inside that package we declare a class A which is public and inside that class, we declare a method m1 which is also public. Now we create another package pack2 and inside that pack2 we import pack1 and declare a class B and in class B’s main method we create an object of type class A and trying to access the data of method m1.
Compiling and saving the above code by using the below command line:
If class A is not public while compiling B class we will get a compile-time error saying pack1. A is not public in pack1 and can’t be accessed from the outside package.
Similarly, a member or method, or interface is declared as public as we can access that member from anywhere.
Protected Access Modifier: This modifier can be applied to the data member, method, and constructor, but this modifier can’t be applied to the top-level classes and interface.
A member is declared as protected as we can access that member only within the current package but only in the child class of the outside package.
In the above example, we create three objects using parent reference and child reference and call m1() method on it, and it successfully executed so from the above example we can say that we can access the protected method within the current package anywhere either by using parent reference or by child reference.
Public Access Modifier Private Access Modifier This modifier is applicable for both top-level classes and interfaces. This modifier is not applicable for both top-level classes and interfaces. We can access public members from the non-child class of outside package. We can’t access protected members from the non-child class of outside package. We can access public members anywhere from the outside package. We can access protected members only through child reference from the outside package. The public modifier is more accessible than the protected modifier. This modifier is more restricted than the public modifier.
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