Why I always got a warning when compiling

Question

this is a small test on how to use Vector, i know it may not necessary
my problem is the compiler always warns me that
warning
==============================
Note: F:\SmallTest_Car.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
(how to apply -Xlint, when use jcreator 3.5?)
Process completed.
==============================
can you help me find out the very reason?
this is my program
=================
class Car
     double dHoursParked;
     double dCharges;
     public Car(double dFrist, double dSecond)
          dHoursParked=dFrist;
          dCharges=dSecond;
}//end class car-----------------
import java.util.*;
class SmallTest_Car
     public static void main(String args[])
          Vector carRecords=new Vector(5);
          carRecords.add(new Car(1.0,2.0));
     }//end main
}//end class question1after catch Exception, also got warning
=============
import java.util.*;
class SmallTest_Car
     public static void main(String args[])
          Vector carRecords=new Vector(5);
          try
               carRecords.add(new Car(1.0,2.0));
          catch(Exception e){     }
     }//end main
}//end class question1

Answer 1

- ignore the warning as it is not an error.worst suggestion.Except there are cases where valid working code produces warnings of this type which cannot be avoided. In some cases you have to just ignore the warning.