setRefNumber

Spørgsmålet lyder:

Add a further field, refNumber, to the Book class. This field can store a reference number for a library, for example. It should be of type String and initialised to the zero length string ("") in the constructor as its initial value is not passed in a parameter to the constructor. Instead, define a mutator for it with the following signature:

public void setRefNumber(String ref)

The body of this method should assign the value of the parameter to the refNumber field. Add a corresponding getRefNumber accessor to help you check that the mutator works correctly.

____________________________

class Book
{
   
    private String author, title;
    private int pages,

    public Book(String bookAuthor, String bookTitle, int pages)
    {
        author = bookAuthor;
        title = bookTitle;
        this.pages = pages;
       
    }

    // Add the methods here ...
   
    public String getAuthor()
    {
        return author;
    }
   
    public String gettitle()
    {
        return title;
    }
   
    public void printAuthor()
    {
        System.out.println(author);
    }
   
    public void printTitle()
    {
        System.out.println(title);
    }
   
    public int getpages()
    {
        return pages;
    }
   
    public void printDetails()
    {
        System.out.println(" Title:" + title + ", Author:" + author + ", pages:" + pages);
    }
   
}

Det eneste jeg har lavet er de blå mærker, men håber i kan hjælpe mig videre?

Mvh Mads