Something

/**
 * A class that maintains information on a book.
 * This might form part of a larger application such
 * as a library system, for instance.
 *
 * @author (Insert your name here.)
 * @version (Insert today's date here.)
 */
class Book
{
    // The fields.
    private String author;
    private String title;
    private int pages;
    private String refnumber;
    private int borrowed;

    /**
     * Set the author and title fields when this object
     * is constructed.
     */
    public Book(String bookAuthor, String bookTitle, int bookPages)
    {
        author = bookAuthor;
        title = bookTitle;
        pages = bookPages;
        refnumber = "";
        borrowed = 0;
    }
    public String getAuthor()
    {
        return author;
    }
    public String getTitle()
    {
        return title;
    }
     public int getPages()
    {
        return pages;
    }
    
     public void setRefNumber(String ref)
    {
        refnumber = ref;
        if ( refnumber.length() < 3) {
            refnumber = "";
            System.out.println("ERROR REFERENCE MUST BE ATLEAST 3 CHARACTERS");
        }
        else {refnumber = ref ;
        }
    }
    
    public String getRefnumber()
    {
        return refnumber;
    }
    public int getBorrowed()
    {
        return borrowed;
    }
    public int increaseBorrowed()
    {
        borrowed = borrowed + 1;
        return borrowed;
    }
    public void printAuthor()
    {
        System.out.println("Author - "+ author +" ");
    }
       public void printTitle()
    {
        System.out.println("Title -  "+ title +" ");
    }
        public void printPages()
    {
        System.out.println("Pages -  "+ pages +" ");
    }
       
    public void printDetails()
    {
        if( refnumber.length() > 0) {
            System.out.println("Title - "+ title +", Author - "+ author +", Pages - "+ pages +", Reference Number - " + refnumber +". Number of times borrowed " + borrowed +".");
        }
        else {
            System.out.println("Title -  "+ title +", Author - "+ author +", Pages -"+ pages +". ZZZ. Number of times borrowed " + borrowed +".");
        }
    }
}