Access Modifiers in Java

There are two types of modifiers in java

  • Access modifiers
  • No-Access modifiers

The access modifiers in java specifies scope of a data member, method, constructor or class.

there are 4 types of java access modifiers :

  • private
  • default
  • protected
  • public

Understanding all java access modifiers

Let's understand the access modifiers by a simple table.

Access Modifier within class within package outside package by subclass only outside package
Private Y N N N
Default Y Y N N
Protected Y Y Y N
Public Y Y Y Y

Access control modifier

Java language has four access modifier to control access levels for classes, variable methods and constructor.

1.Default - Default has scope only inside the same package

2.Public - Public scope is visible everywhere

3.Protected - Protected has scope within the package and all sub classes

4.Private - Private has scope only within the classes

Non-access modifiers

here are many non-access modifiers such as static, abstract, synchronized, native, volatile, transient etc. Here, we will learn access modifiers.

1)private access modifier

the private access modifier is accessible only within class

Example of private access modifier

						 
class A{  
private int data=30;  
private void msg(){System.out.println("Hello java");}  
}  
  
public class Simple{  
 public static void main(String args[]){  
   A obj=new A();  
   System.out.println(obj.data);//Compile Time Error  
   obj.msg();//Compile Time Error  
   }  
}  							 

Role of private Constructor

If you make any class constructor private ,you cannot create the instances of the class from outside the class.For Example

				
 class A{  
private A(){}//private constructor  
void msg(){System.out.println("Hello java");}  
}  
public class Simple{  
 public static void main(String args[]){  
   A obj=new A();//Compile Time Error  
 }  
}  

Note: A class cannot be private or protected except nested class.

Default access modifier

If you don't use any modifier, it is treated as default by default. The default modifier is accessible only within package.

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.

	
						 //save by A.java  
package pack;  
class A{  
  void msg(){System.out.println("Hello");}  
}

	
//save by B.java  
package mypack;  
import pack.*;  
class B{  
  public static void main(String args[]){  
   A obj = new A();//Compile Time Error  
   obj.msg();//Compile Time Error  
  }  
}  

Protected access modifier

the protected access modifieris 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.

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.

	
 //save by A.java  
package pack;  
public class A{  
protected void msg(){System.out.println("Hello");}  
}  

	
//save by B.java  
package mypack;  
import pack.*;  
  
class B extends A{  
  public static void main(String args[]){  
   B obj = new B();  
   obj.msg();  
  }  
}  

Public access modifier

the public access modifier is accessible everywhere.it has the widest scope among all other modifiers

Example of public access modifier

	
  //save by A.java  
  
package pack;  
public class A{  
public void msg(){System.out.println("Hello");}  
}
	
//save by B.java  
  
package mypack;  
import pack.*;  
  
class B{  
  public static void main(String args[]){  
   A obj = new A();  
   obj.msg();  
  }  
} 

Java access modifiers with method overriding

If you are overriding any method, overridden method (i.e. declared in subclass) must not be more restrictive.

	
  class A{  
protected void msg(){System.out.println("Hello java");}  
}  
  
public class Simple extends A{  
void msg(){System.out.println("Hello java");}  
 public static void main(String args[]){  
   Simple obj=new Simple();  
   obj.msg();  
   }  
}  
Note :The default modifier is more restrictive than protected. That is why there is compile time