Access specifier in java

Programming in Java

Object Oriented in Java

Advanced topics in Java

Java has four types of access specifiers and they are declared as following :

a. public :

 public int a;

b. protected :

 protected int b;

c. default (no specifier) :

 int c;

d. private :

 private int d;

All access modifiers can be understood with the following examples :

case 1 : Access variables within the class.

class A
{
  public int a=10;
  protected int b=20;
  int c=30;
  private int d=40;

  void show()
  {
    System.out.println("a="+a+" b="+b+" c="+c+" d="+d);
  }
}

class CheckMain
{
  public static void main(String args[])
  {
     A obj= new A();
     obj.show(); // all variables may be printed as they are used within the class.
  }
}

case 2 : Access variable in the subclass of the same package.

class A
 {
   public static int a=10;
   protected static int b=20;
   static int c=30;
   private static int d=40;
 }

class B extends A
{
public static void main(String args[])
{
System.out.println(“a=”+a);
System.out.println(“b=”+b);
System.out.println(“c=”+c);
//System.out.println(“d=”+d); uncommenting this line will give error..
} //..as private variable cant be used here.
}

case 3 : Access variable in the non-subclass of the same package.

class A
 {
   public int a=10;
   protected int b=20;
   int c=30;
   private int d=40;
 }

class B
{
public static void main(String args[])
{
A obj= new A(); // need to create objects to access properties of another class without inheritance.
System.out.println(“a=”+obj.a);
System.out.println(“b=”+obj.b);
System.out.println(“c=”+obj.c);
//System.out.println(“d=”+obj.d); uncommenting this line will give error as private variable cant be used here.
}
}

case 4 : Access variable in the subclass of a different package.

package pkg1;
class A
{
  public static int a=10;
  protected static int b=20;
  static int c=30;
  private static int d=40;
}

package pkg2;
import pkg1.*;
class B extends A
{
  public static void main(String args[])
  {
    System.out.println("a="+a);
    System.out.println("b="+b);
    //System.out.println("c="+c); uncommenting this line will give error as default variable can not be accessed outside package.
    //System.out.println("d="+d); uncommenting this line will give error as private variable is out of scope
  }
}

case 5 : Access variable in the subclass of a different package.

package pkg1;
class A
{
  public int a=10;
  protected int b=20;
  int c=30;
  private int d=40;
}

package pkg2;
import pkg1.*;
class B 
{
  public static void main(String args[])
  {
    A obj= new A(); // need to create objects to access properties of another class without inheritance.
    System.out.println("a="+obj.a); // only public variable may be accessed here.
    //System.out.println("b="+obj.b);
    //System.out.println("c="+obj.c);
    //System.out.println("d="+obj.d); 
}
}