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twodayslate

08-13-2008 09:54 PM

Explain static

Code:

private static studentNum=0;

public Student() {

studentNum++;

}

public static int getStudentNum() { return studentNum; }

public int getStudentNum is only static so it can return the static StudentNum correct? To call it you would say Student.bob.getStudentNum();

Am I understanding this?

shyam

08-14-2008 06:44 PM

Quote:

Originally Posted by twodayslate (Post 723251)

public int getStudentNum is only static so it can return the static StudentNum correct? To call it you would say Student.bob.getStudentNum();?

who is bob?

you access static methods only via the class name so, Student.getStudentNum() (assuming that the snippet you posted is part of the Student class)

twodayslate

08-15-2008 02:19 AM

Thanks for the reply!

Quote:

Originally Posted by shyam (Post 723635)

who is bob?

you access static methods only via the class name so, Student.getStudentNum() (assuming that the snippet you posted is part of the Student class)

Code:

Student bob = new Student();

So to get bob's student number what do you call? It can't be Student.getStudentNum();, is it Student.bob.getStudentNum();?

icm9768

08-15-2008 03:57 AM

It would be Student.getStudentNum(). Static variables are shared among ALL instances of the class so it doesn't require you to reference it via any particular instance (bob in your case), nor should you for clarity sake. Using Student.bob.getStudentNum() would work, but it will create a warning when you compile your code.

Just as a side note, in case you didn't already realize, that each Student class you instantiate will not have a unqiue studentNum. Every instance will have the same id (i.e. The total number of Student objects you have created).

shyam

08-15-2008 06:38 AM

Quote:

Originally Posted by twodayslate (Post 723762)

Code:

Student bob = new Student();

So to get bob's student number what do you call? It can't be Student.getStudentNum();, is it Student.bob.getStudentNum();?

as icm9768 has rightly pointed out there is no bob's student number...if you want to store bob's student number you should store it in a member variable sorta like this

Code:

class Student {

  private static studentNum=0;

  private myNumber;

  public Student() {

    this.myNumber = studentNum++;

  }

  public static int getStudentNum() { 

    return studentNum; 

  }

  public int getNumber() {

    return myNumber;

  }

}

Code:

Student bob   = new Student(),

        dylan = new Student();



Student.getStudentNum(); // returns 2

bob.getNumber(); // gives 0

dylan.getNumber(); // gives 1

twodayslate

08-15-2008 10:13 PM

Thanks.
This was a question for my summer assignment. (Dont worry, you did not do my homework for me)
I understand it now. Thanks!

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