Access Modifier

1. Overview

2. Example

2.1 private

class A{  
private int data=40;  
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  
   }  
}  

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  
 }  
}  

2.2 default

//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  
  }  
}  

2.3 protected

//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();  
  }  
}  

Output:Hello

2.4 public

//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();  
  }  
}  

Output:Hello

2.5 Java Access Modifiers with Method Overriding

If you are overriding any method, the overridden method (i.e. declared in a 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");}//C.T.Error. This is invalid
protected void msg(){System.out.println("Hello java");} // This is valid
 public static void main(String args[]){  
   Simple obj=new Simple();  
   obj.msg();  
   }  
}  

3. Reference

https://www.javatpoint.com/access-modifiers