public 
class ObjectExample
{

   public static
   void main ( String [] args )
   {
      A q ;
      q = new A() ; // syntax to instantiate an object

      q.k = 4 ;    // syntax to access the instance variable of an object
      System.out.println("q.k= "+q.k) ;  // prints 4

      A r ;
      r = new A() ;
      r.k = 2 ;

      System.out.println("q.k= "+q.k) ; // prints 4
      System.out.println("r.k= "+r.k) ; // prints 2

      r.incrementK() ; // syntax to invoke a method of an object

      System.out.println("q.k= "+q.k) ; // prints 4
      System.out.println("r.k= "+r.k) ; // prints 3

      A u ;
      u = q ;    // u is an "alias" for q
      u.incrementK() ;

      System.out.println("q.k= "+q.k) ; // prints 5
      System.out.println("r.k= "+r.k) ; // prints 3
   }
}

class A
{
   int k ;  // instance variable

   void incrementK()  // instance method
   {
      k++ ; 
   }
}