无法将自定义数据类型转换为字符串？

Question

我正在使用java序列化开发一个库系统。当我实现书籍问题部分时，我需要存储书籍的细节和成员的详细信息。

为此，我使用了“issueNewBook”方法。该方法属于“Book”类。所以当我调用此方法时，它有一个属性“libraryMember member”，这将返回成员id。

在我调用此方法之后，它表示字符串无法转换为libraryMember？我不知道如何解决这个问题。我尝试了所有我知道的事情。你的帮助在这个时候非常重要。谢谢。

图书馆成员班：

public class libraryMember implements Serializable{


    String userType;
    String username;
    String password;
    String confirmPassword;
    private String name;
    public int memberNumber;
    private SetOfBooks currentLoans = new SetOfBooks();
    private static int memberCount = 0;


    public libraryMember() {

        userType=null;
        username=null;
        password=null;
        confirmPassword=null;
    }


public libraryMember(String aName){

name= aName;
memberNumber = memberCount++;
currentLoans = new SetOfBooks();

}

    @Override
    public String toString(){

return Integer.toString(memberNumber) + " " + name;


}
    public void borrowBook(Book aBook){

    currentLoans.addBook(aBook);
    aBook.setBorrower(this);

    }
    public String getUserType(){

    return this.userType;
    }

    public Object getName() {
         return this.username;
    }

    public String getPassword() {
        return this.password;
    }


    public String getConfirmPassword() {
        return this.confirmPassword;
    }

    public void singUp(Object userType, String username, String password) {

        this.userType = (String) userType;
        this.username = username;
        this.password = password;

    }

}

预订课程：

public class Book implements Serializable{

    public String title;
    public String author;
    public String publisher;
    public String isbn;
    public int noOfCopies;
    private libraryMember borrower = null;
    private static int bookCount = 0;
    private int accessionNumber;
    public String Issuedate;
    public String returnDate;

    public Book(String name){

    title = name;
    accessionNumber = bookCount++;

    }

   public void addNewBook(int bookID, String title, String author,String publisher,String isbn,int noOfCopies) {

        this.accessionNumber = bookID;
        this.title = title;
        this.author = author;
        this.publisher = publisher;
        this.isbn=isbn;
        this.noOfCopies=noOfCopies;

    }

   public void issueNewBook(int bookID,String title,libraryMember member,String issuedDate,String returnDate)
   {
   this.accessionNumber= bookID;
   this.title= title;
   this.borrower=member;
   this.Issuedate = issuedDate;
   this.returnDate=returnDate;


   }
    public int getBookID()
    {
    return accessionNumber+1;

    }
    public String getBookName()
    {

    return title;
    }

    void setBorrower(libraryMember theBorrower){

    borrower = theBorrower;

    }

    libraryMember geMember(){

    return borrower;

    }

}

书籍问题按钮动作：

// TODO在这里添加您的处理代码：

 ArrayList<Book> bookList = new ArrayList();

        int flag = 0;
        try {
            FileInputStream fis = new FileInputStream("issuedBook.dat");
            ObjectInputStream ois = new ObjectInputStream(fis);

            Book book;
            while ((book = (Book) ois.readObject()) != null) {
                if (book.getBookName().equals(issue_BookNameArea.getText())) {
                    flag = 1;
                    break;
                }
                bookList.add(book);
            }
            ois.close();
            fis.close();
        }
        catch(FileNotFoundException e)
        {


        }
        catch (EOFException e) {
        } catch (ClassNotFoundException ex2) {
        } catch (IOException e) {
        }

        if (flag == 0) {
            //write to file only if name doesn't exist
          Book bk = new Book(getName());

            String s = issue_BookNameArea.getText();


      libraryMember member = null;

            bk.issueNewBook((Integer.parseInt(issue_BookIdField.getText())),issue_BookNameArea.getText(),issue_MemberID.getText(), issueDate_dateChooser.getText(), returndaateField.getText());

            bookList.add(bk);
            try {
                FileOutputStream fos;
                ObjectOutputStream oos;
                fos = new FileOutputStream("newMember.dat");
                oos = new ObjectOutputStream(fos);

                Book b;
                Iterator i = bookList.iterator();
                while (i.hasNext()) {
                    b = (Book) i.next();
                    oos.writeObject(b);
                    oos.flush();
                }

                fos.close();
                oos.close();
               // dispose();


            } catch (IOException e) {
            }

        }

}

问题包含方法：

bk.issueNewBook（（Integer.parseInt（issue_BookIdField.getText（））），issue_BookNameArea.getText（），issue_MemberID.getText（），issueDate_dateChooser.getText（），returndaateField.getText（））;

错误来自：

issue_MemberID.getText（）

错误：

字符串无法转换为libraryMember