Hi to all,
Thanks for your help .It really helps me a lot.Although you told
me that how to do this homework but after reading your replies i m also
facing problem in doing that but atlast i did it but i want to know that is
my approach right? and if there is any other alternative please tell me .
Here what i did
As you told me to initialize StudentRecord i did it
public class Student {
/**Create an instance of Student class */
public Student(){
studentRecord = new StudentRecord();
}
Then in the same class(Student) i wrote setter and getter method in this way
public String getName(){
return studentRecord.getName();
}
public void setName(String name){
studentRecord.setName(name);
}
and then in the main class(in my case MyOwnProjectMain) I set and call it in
this way
annaStudent.setName("Anna");
System.out.println("Name = " + annaStudent.getName());
Is this approach is right? . My question is can we do it without creating
the above setName and getName method in Student class
Actually in the first place I initialize studentRecord as you told me in the
Student constructor then without writing the above setter and getter
methods(setName and getName) in Student class i try to access the name in
this way
annaStudent.studentRecord.setName("Anna");
But it again says that studentRecord has private access in Student class
Also as Vasile says that try
StudentRecord rec = annaStudent.getStudentRecord();
I also did it but it syas no symbol found in Student class then i replace
the getStudentRecord() to getName() and setName() but it again says that no
setName and getName method in Student class.
So please tell me is it necessary to create these setName and getName method
that i did, in the Student class or is there any alternative to do it
.Thanks for your help
On Thu, Mar 26, 2009 at 10:56 AM, * ^ * <[email protected]> wrote:
>
> On Mar 26, 6:33 am, Ryu <[email protected]> wrote:
> > Hi to all,
> > Hope everyone is fine.Sorry i have a problem with this
> > lab's homework as other people was , I also read the emails that
> > previously posted regarding this lab's homework but i still unable to
> > do it .I stuck at a point that how we access the StudentRecord class
> > setName() method using Student class object.First i try this. I have
> > only set and getStudentId methods in my Student class and also
> > increasecount method
> >
> > // Create an object instance of Student
> > class.
> > Student annaStudent =new Student();
> >
> > // Increament the studentCount by
> > invoking a static method.
> > Student.increaseStudentCount();
> >
> > annaStudent.studentRecord.setName("Anna");
> >
> > but it shows error that studentRecord has private access in Student
> > class. The same thing was follow by another group member before and in
> > reply of this the answer is you initialize student record like this
> >
> > annaStudent.studentRecord = new
> > StudentRecord();
> >
> > but when i try this it again says that studentRecord has private
> > access in Student class.
> >
> > Secondly i follow another group member technique and
> > that is make setter and getter method in Student class like this
> >
> > public void setStudentName
> > (String name){
> >
> > studentRecord.setName(name);
> > }
> >
> > public String
> > getStudentName(){
> > return
> > studentRecord.getName();
> > }
> >
> > but when i call it in main like
> >
> > annaStudent.setStudentName("Anna");
> >
> > annaStudent.setStudentId(1);
> >
> > and run the program i got an error message that
> >
> > Exception in thread "main" java.lang.NullPointerException
> > at Student.setStudentName(Student.java:46)
> > at MyOwnProjectMain.main(MyOwnProjectMain.java:27)
> >
> > At (Student.java:46) i have this line
> >
> > studentRecord.setName(name);
> >
> > and (MyOwnProjectMain.java:27) i have this one
> >
> > annaStudent.setStudentName("Anna");
> >
> You had tried two ways. In the first: You had tried to access a non
> visible member. Whereby, in the second: You had tried to access a
> member that has not been initialised.
>
> > So please you people tell me that how can i access StudentRecord
> > setName() method using Student class object
> First, initialise studentRecord. Then, you can access it in <main>
> like you did before. For example:
> In student:
> // Initialise studentRecord.
> Student(){
> studentRecord=new StudentRecord();
> }
>
> >
> > Second, studentRecord is private and for private we use setter and
> > getter methods , i want to ask that is it necessary to made setter and
> > getter for studentRecord or we can access StudentRecord methods
> > without making setter and getter method in Student class
> >
> > Third why i got null pointer exception
> You had access studentRecord when it has not been initialised.
>
> >
> > thanks in advance
>
> >
>
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