Java Access Specifiers - Part 2

In this Part, we will check how the specifiers behave when the classes defined in 
different packages are trying to access member variables of other classes.

  Private Access Specifier  

Consider the following code,

package com.vk;

public class Vk {
 
  private int a=40; // Access Specifier -> Private.
 
}



package com.vk.first;

import com.vk.Vk;

class Vk1
{
 public static void main(String args[])
 {
  System.out.println("Creating a new Object");
  
  Vk v=new Vk();
  
  System.out.println("Trying to access the Private member variable");
  v.a=50;
  
 }
}


In the above program, we have a defined a member variable 'a'  with 
Access Specifier -> Private and we are trying to access this variable from a class 

'Vk1'which is defined in a different package.

Run this program and check if the compilation is success.

Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
 The field Vk.a is not visible

 at com.vk.first.Vk1.main(Vk1.java:14)



Private Variables cannot be accessed by any other class, they can only 

be accessed in the 
class where they are defined.

Protected Access Specifier 

Now lets change the access specifier for our variable 'a' to protected and check if 
compilation is clean.

package com.vk;

public class Vk {
 
 protected int a=40; // Access Specifier -> Protected.
 
}




package com.vk.first;

import com.vk.Vk;

class Vk1
{
 public static void main(String args[])
 {
      System.out.println("Creating a new Object");
  
      Vk v=new Vk();
  
      System.out.println("Trying to access the Protected member variable");
      v.a=50;
  
 }
}




Exception in thread "main" java.lang.Error: Unresolved compilation problems: 
 Vk cannot be resolved to a type
 Vk cannot be resolved to a type

 at com.vk.first.Vk1.main(Vk1.java:8)




Protected variables cannot be accessed from classes defined in different package. 

Default Access Specifier

To define a variable with default access specifier, dont mention anything before 

the data_type.

Now lets change the access specifier for our variable 'a' to default and check if 
compilation is clean.

package com.vk;

public class Vk {
 
 int a=40; // Access Specifier -> Default.
 
}




package com.vk.first;

import com.vk.Vk;

class Vk1
{
 public static void main(String args[])
 {
  System.out.println("Creating a new Object");
  
  Vk v=new Vk();
  
  System.out.println("Trying to access the Default member variable");
  v.a=50;
  
 }
}





Exception in thread "main" java.lang.Error: Unresolved compilation problem: 
 The field Vk.a is not visible

 at com.vk.first.Vk1.main(Vk1.java:14)




Default variables can be accessed by any other class defined in the same package.

Public Access Specifier

Now lets change the access specifier for our variable 'a' to Public and check if 

compilation is clean.

package com.vk;

public class Vk {
 
  public int a=40; // Access Specifier -> Public.
 
}



package com.vk.first;

import com.vk.Vk;

class Vk1
{
 public static void main(String args[])
 {
  System.out.println("Creating a new Object");
  
  Vk v=new Vk();
  
  System.out.println("Trying to access the Public member variable");
  v.a=50;
  
 }
}



Creating a new Object
Trying to access the Public member variable