更改Jtable单元值

Question

I have a jtable that keep book file records and sho them.

I create a "Borrow" jbutton that when clicked to a row that not borrowed, The "Borrow Status" of that row should change to "Yes".

I use this codes, but did not changed!

public class user_AllBooks extends AbstractTableModel{
BookInformation book_info=new BookInformation();
String[] columns=new String[]{"Book Name","Book Date", "Book ID","Borrow Status"};
ArrayList<BookInformation> bData=new ArrayList<BookInformation>();

public user_AllBooks(){
    try{
        BufferedReader br=new BufferedReader(new FileReader("AllBookRecords.txt"));
        String line;
        while((line = br.readLine()) != null){
            bData.add(initializeBookData(line));
        }
        br.close();
    }
    catch(IOException ioe){

    }
}

public BookInformation initializeBookData(String myline){
    BookInformation book_infos=new BookInformation();
    String[] celledLine=myline.split("     ");
    book_infos.setBookName(celledLine[0]);
    book_infos.setBookDate(celledLine[1]);
    book_infos.setBookID(celledLine[2]);
    book_infos.setBorrowStatus(celledLine[3]);
    return book_infos;
}

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

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

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

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

    switch(columnIndex){     
        case 0:
            value=bookInf.getBookName();
            break;
        case 1:
            value=bookInf.getBookDate();
            break;
        case 2:
            value=bookInf.getBookID();
            break;
        case 3:
            value=bookInf.getBorrowStatus();
            break;
        default :
            value="...";
    }
    return value;    
}
}

Second Class:

public class user_AllBooksM extends JFrame implements ActionListener{
user_AllBooks uAllBooks=new user_AllBooks();
final JTable bTable=new JTable(uAllBooks);
JButton borrowButton;
public user_AllBooksM(){
    setTitle("All Books");
    exitButton=new JButton("Exit");
    borrowButton=new JButton("Borrow");
    borrowButton.addActionListener(this);
    JPanel Bpanel=new JPanel();
    Bpanel.setLayout(new FlowLayout());
    JScrollPane sp=new JScrollPane(bTable);
    Bpanel.add(sp);
    Bpanel.add(borrowButton);
    this.add(Bpanel);
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.setBounds(300, 60, 550, 550);
    this.setResizable(false);
    this.setVisible(true);
}

@Override
public void actionPerformed(ActionEvent event) {
        borrowInitialize(bTable.getSelectedRow());  
}

public void  borrowInitialize(int row){
    if(uAllBooks.getValueAt(row, 3).equals("yes")) {
        JOptionPane.showMessageDialog(null, "This Book Was Borrowed");
    }
    else{
        uAllBooks.setValueAt("Yes", row, 3);
        uAllBooks.fireTableRowsUpdated(row, row);
    }
}

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

}

Thanks.

Answer 1

To override setValueAt You should use:

@Override
public void setValueAt(Object value, int row, int col)
{
    BookInformation book_infos = bData.get(row);
    if (col==0)
    book_infos.setBookName((String)value);
    else if (col==1)
    book_infos.setBookDate((String)value);
    else if (col==2)
    book_infos.setBookID((String)value);
    else if (col==3)
    book_infos.setBorrowStatus((String)value);
    fireTableCellUpdated(row,col);
}

Define this method within class user_AllBooks

Answer 2

You have overridden the getValueAt method. So it always returns value from your bData arraylist.

public Object getValueAt(int rowIndex, int columnIndex) {
    BookInformation bookInf=bData.get(rowIndex);

So you need to implement the setValueAt method also in your table model so change actual data in the bData arraylist.

Also note that bTable.getSelectedRow() will give you selected row in terms of the view. In model the index might be different if the table is sorted.

Answer 3

You could use TableModel#setValueAt , but you would also become responsible for updating the table, which breaks the MCV model.

Instead, you could add a setBorrowed method to your user_AllBooks class.

public void setBorrowed(int row, boolean borrowed) {
    BookInformation book = bData.get(row);
    book.setBorrowedState(borrowed);
    fireTableCellUpdated(row, 3);
}