// Lang_17 ['null' keyword].nova


// The application class.
class NullKeywordApp
{
   // Application class's "main" function.
   public static void main( String[] args )
   {
      // Declare a reference.
      // All new uninitialized references are automatically null.
      Integer i;

      // Call "method" with a null argument.
      method0( null );

      // Check if i is not null.
      if ( i != null )
      {
         Stream.writeLine( "i is not null." );
      }
      else
      {
         Stream.writeLine( "i is null." );
      }


      // Create a new "B" object.
      B b = new B( );

      // Check if b's "b" attribute is null.
      if ( b.b == ( null ) )
      {
         Stream.writeLine( "b is null." );
      }
      else
      {
         Stream.writeLine( "b is not null." );
      }
   }


   private static Integer method0( Integer i )
   {
      // Return null.
      return null;
   }


   // Used to demonstrate ambiguous method calls when passing "null" arguments.
   // Uncomment this method to get the "ambiguous method call" compilation error.
/*   private static String method0( String s )
   {
      return s;
   }*/
}


class B
{
   // Instance attribute.
   public Boolean b;

   // Empty constructor.
   public B( )
   {
      // Attribute "b" will remain null.
   }
}