public void testNullString ()
    {
       String realString = "qljf";
       String nullString = null ;
 
        testI(realString, "error 1");
        testI(null      , "error 2");
        testI(nullString, "error 3");
    }
    private static void testI(final String testee, final String msg) {
        if ( !(testee instanceof String)) {
            System.out.println(testee + " is not an instaceof String.  " + msg);
        }
    }

class Person (){
 
   public boolean equals(Object o) {
      if (!(o instanceof Person)) return false ;
      
      Person obj = (Person)o ; // obj cannot be null
 
      return obj.__fName.equals (this.__fName) ;
   }
 
   private String __fName ;
}