Question

I use this method to add a new row to my jtable and file too.

But when i clicked to add button, That new record added to jtable, but when i see the text file, I found something like this:

myproject.Library.BookInformation@9899472

where is my mistake?

My code:

public class MainS extends JFrame{

   final AllBooks allBooks=new AllBooks();
   final JTable Btable=new JTable(allBooks);

   public MainS(){
       JButton AddBookButton=new JButton("Add New Book");
       AddBookButton.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) { 

           AddDialogS adddialog=new AddDialogS(MainS.this);
           adddialog.setVisible(true);
           BookInformation B_info=adddialog.getBookInfos();
           if(B_info != null){
               allBooks.AddRow(B_info);
           }
        }
    });

    JPanel Bpanel=new JPanel();
    Bpanel.setLayout(new FlowLayout());
    JScrollPane sp=new JScrollPane(Btable);
    Bpanel.add(sp);
    Bpanel.add(AddBookButton);
    this.add(Bpanel);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setBounds(300, 60, 550, 550);
    this.setVisible(true);
   }

   public static void main(String[] args){
       new MainS();
   }
}

second class for add new record:

public class AddDialogS extends JDialog{
BookInformation bookinform=new BookInformation();

public AddDialogS(JFrame owner){
    super(owner,"Add New Book!", true);
    JButton OkButton=new JButton("Ok");
   final JTextField nameTF=new JTextField(10);
   JLabel namelbl=new JLabel("bookname");
   final JTextField dateTF=new JTextField(10);
   JLabel datelbl=new JLabel("bookDate");
   final JTextField idTF=new JTextField(10);
   JLabel IDlbl=new JLabel("bookId");


    OkButton.addActionListener(new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
            bookinform.setBookName(nameTF.getText().trim());
            bookinform.setBookDate(String.valueOf(dateTF.getText().trim()));
            bookinform.setBookID(String.valueOf(idTF.getText().trim()));
            AddDialogS.this.dispose();
        }
    });

    JPanel panel=new JPanel(new FlowLayout());
    panel.add(OkButton);
    panel.add(nameTF);
    panel.add(dateTF);
    panel.add(idTF);
    panel.add(namelbl);
    panel.add(datelbl);
    panel.add(IDlbl);
    this.add(panel);
    this.setBounds(10, 30, 400, 500);
}

public BookInformation getBookInfos(){
    return bookinform;
}
}

My table model Class:

public class AllBooks extends AbstractTableModel{
BookInformation Binfos1=new BookInformation();

String[] Bcol=new String[]{"Name","Date","Id"};
List<BookInformation> Bdata=new ArrayList<BookInformation>();

public AllBooks(){
    try{
        FileReader fr=new FileReader("AllBookRecords.txt");
        BufferedReader br=new BufferedReader(fr);
        String line;

        while( (line=br.readLine()) !=null){
            Bdata.add(initializeBookInfos(line));
        }
        br.close();
    }
    catch(IOException ioe){

    }
}

public static BookInformation initializeBookInfos(String str){
    BookInformation Binit=new BookInformation();
    String[] bookCellArray=str.split("     ");
    Binit.setBookName(bookCellArray[0]);
    Binit.setBookDate(bookCellArray[1]);
    Binit.setBookID(bookCellArray[2]);
    return Binit;
}

public void AddRow(BookInformation bookinfo){
    if(AddToFile(bookinfo)){
        Bdata.add(bookinfo);
        fireTableRowsInserted(Bdata.size()-1, Bdata.size()-1);
    }
    else{
        JOptionPane.showMessageDialog(null, "Unable Add To File"+bookinfo.getBookName());
    }
}

public boolean AddToFile(String bookinfos){
    try{       
        PrintWriter Bpw=new PrintWriter(new FileOutputStream("AllBookRecords.txt",true));
        Bpw.println(bookinfos);
        return true;
    }
    catch(IOException ioe){
        return false;
    } 
}

@Override
public String getColumnName(int col){
    return Bcol[col];
}

@Override
public int getRowCount() {
    if(Bdata !=null){
    return Bdata.size();
    }
    else{
        return 0;
    }
}

@Override
public int getColumnCount() {
    return Bcol.length;
}

@Override
public Object getValueAt(int rowIndex, int columnIndex) {
    BookInformation binfo=Bdata.get(rowIndex);
    Object value;

    switch(columnIndex){

        case 0:
            value=binfo.getBookName();
            break;
        case 1:
            value=binfo.getBookDate();
            break;
        case 2:
            value=binfo.getBookID();
            break;
        default :
            value="...";  
    }
    return value;

}
}

My BookInformation Class:

public class BookInformation {

private String BookName;
private String BookDate;
private String BookID;

public String getBookName() {
    return BookName;
}

public void setBookName(String book_name) {
    this.BookName = book_name;
}

public String getBookDate() {
    return BookDate;
}


public void setBookDate(String book_date) {
    this.BookDate = book_date;
}


public String getBookID() {
    return BookID;
}

public void setBookID(String Book_id) {
    this.BookID = Book_id;
}
}

Thanks for help.

Answer 1

Looks like what you get in the file is a result of method toString() invocation on an object of this class: myproject.Library.BookInformation.

So the quickest fix in your case would be to override toString() method for BookInformation to return what you need.

public String toString() {
    return getBookName(); // Or whatever you see fit.
}

Even if later you’ll change your code not to rely on toString() a meaningful implementation is not going to hurt.

Unlike in another answer you do NOT have to change code for AddToFile if you override toString(). However, if you don’t modify code for BookingInformation, then you would have to craft string value when you call AddToFile similar to what was suggested:

AddToFile(bookinfo.getBookName()) // Or whatever you see fit.

Another even better way would be to modify AddToFile method to accept BookingInformation as a parameter.

public boolean AddToFile(BookingInformation bookinfos){
    try{       
    PrintWriter Bpw=new PrintWriter(new FileOutputStream("AllBookRecords.txt",true));
    Bpw.println(bookinfos.getBookName()); // Or whatever you see fit.
    return true;
    }
    catch(IOException ioe){
    return false;
    } 
}