Ok still having problems with this.
First problem - how to get studentId to increment? Can you do studentId
++ for an Integer object? In the end I ended up making studentId a
class variable that is incremented and creating an instance variable
of int type called Id that holds the student's studentId. Otherwise
the studentId was always 3 when printed - might have just been
printing in the wrong order, but shouldn't you be able to assign each
student their own studentId?
Second problem - forgot what it was...
Have submitted the homework now, and it works, but don't feel its as
was intended. Could just be misinterpretation of the instructions on
my part though... For example:
The Student class has studentId instance variable whose type is
Integer type.
-I've made studentId a class variable and a separate instance variable
called Id.
On May 15, 11:05 am, "Nick Dolan" <nickdo...@gmail.com> wrote:
> Take studentercord out from settee Anna is the object and you call set on that
>
> e.g
> anna.setName("Anna");
>
> Nick
> 07961171046
>
> -----Original Message-----
> From: Mihai DINCA <mihai.di...@free.fr>
> Date: Sat, 15 May 2010 11:05:35
> To: <jkendal...@gmail.com>
>
> Cc: Java Programming Online Training Course By Sang
> Shin<javaprogrammingwithpassion@googlegroups.com>
> Subject: Re: [java programming] Re: Homework 1014
>
> I think your constructor for the class Student must do "studentRecord =
> new StrudentRecord()" or something like this.
>
> Hope it helps
> mihai
>
> JKay a écrit :
> > Tried to post the entire project here, but moderator said no.
> > Apparently we're not allowed to post large volumes of code, just small
> > snippets?
>
> > The project is 3 classes (StudentRecordExample.java[MAIN],
> > StudentRecord.java,Student.java), which have been modified from the
> > original MyStudentRecordExampleProject so its a bit bulky and could do
> > with a lot of streamlining, but I figure it should work anyways. As
> > said the error I'm getting is:
>
> > Exception in thread "main" java.lang.NullPointerException
> > at StudentRecordExample.main(StudentRecordExample.java:35)
> > Java Result: 1
>
> > I used the 'new' keyword to create an instance of a Student object
> > like so in StudentRecordExample.java:
>
> > Student anna = new Student();
>
> > Then to set the name variable for object anna of class Student, I
> > used:
>
> > anna.studentRecord.setName("Anna");
>
> > which as I understand it gets method setName from class studentRecord.
> > Do I have to explicitly link classes Student and StudentRecord some
> > how for this to work? BTW this line of code where I set anna's name
> > variable is highlighted when I click on the error, and is on line 35.
>
> > On May 14, 6:00 pm, Nic Fox <f...@nicfox.com> wrote:
>
> >> Without seeing your code it's hard to say.
>
> >> So you've used the 'new' keyword to make an instance of a Student
> >> object?
> >> E.g. Student anna = new Student();
>
> >> And then you use something like:
> >> anna.name = "Anna";
>
> >> If you've done those things then it could be an issue with variable
> >> scope perhaps?
>
> >> On 14/05/2010, at 11:47 PM, JKay wrote:
>
> >>> I keep getting the following error when I run my program:
>
> >>> Exception in thread "main" java.lang.NullPointerException
> >>> at StudentRecordExample.main(StudentRecordExample.java:35)
>
> >>> I looked up what java.lang.NullPointException is in the API and found
> >>> this:
>
> >>> "public class NullPointerException
> >>> extends RuntimeException
>
> >>> Thrown when an application attempts to use null in a case where an
> >>> object is required. These include:
>
> >>> * Calling the instance method of a null object.
> >>> * Accessing or modifying the field of a null object.
> >>> * Taking the length of null as if it were an array.
> >>> * Accessing or modifying the slots of null as if it were an array.
> >>> * Throwing null as if it were a Throwable value.
>
> >>> Applications should throw instances of this class to indicate other
> >>> illegal uses of the null object."
>
> >>> Which as far as I understand means that I'm trying to do something
> >>> with a null object. Said object is object anna of class Student, and
> >>> the method on the line that is throwing the exception is me attempting
> >>> to set the name variable for anna to "Anna"
>
> >>> Any ideas?
>
> >>> James
>
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