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 <[email protected]> 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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