Refresh data in JTable when using a DefaultTableModel

Question

I have a JFrame where I construct a JTable.

The JTable is made in two steps:

1. I make a function initTable() where I make my table

2. I make another function initDataintoTable() which ads my data from an arraylist to my table.

Everything works fine until now. The problem comes when I try to update my JTable. In fact, I open a JDialog and I try to a new item on the list. I get to the point of modifying the Arraylist with the new item, but I can't get my table updated after, I don't really know where to put the fireTableDataChanged() for example and how to call it when I want it.

In the initDataintoTable I added a TableModelListener to my DefaultTableModel tablemodel.

protected void initDataIntoTable() {
    tablemodel.setRowCount(0);

    for (//every item on my list) {
    String[] row = {dataitem, dataitem2};
        tablemodel.addRow(row);
    }

    TableModelListener myjtable_listener = new TableModelListener() {
        public void tableChanged(TableModelEvent e) {
                            // I have to write something here to update my table ?
                            // I don't know if it's here where I have to update my table and if it is, how should I call this listener from the place I want to update ?
            tablemodel.fireTableDataChanged(); // ?
        }
    };
    table.getModel().addTableModelListener(jtable_listener);
    //tablemodel.addTableModelListener(myjtable_listener);
    }
}

In my jDialog, I have an ActionListener on the Ok button:

class OKButton implements ActionListener {
     public void actionPerformed(ActionEvent e) {
    // Here I manage to get my updated list of objects
            // What should I call here to update my jtable ?    
    }
}                   
okbutton.addActionListener(new OKButton());

I already saw a few questions on this website, but nothing I tried actually worked with my program. Thank you for your help and sorry for my english.

Answer 1

You never have to call fireTableDataChanged method explicitly since it's up to the TableModel implementation to notify the view when data has been changed (insert/update/delete).

In your case calling tablemodel.addRow(...) is enough: the table model will notify the view that data has changed and this last one will be updated.

okButton.addActionListener(new ActionListener() {
    @Override
    public void actionPerformed(ActionEvent e) {
        ...
        ((DefaultTableModel)table.getModel()).addRow(...);
        ...
    }
};

Edit

You state in a comment:

I can't do jframe.getTable() without having getTable static, and I can't get getTable() static without making table static. After doing this, my program works just like I wanted to.

If you have to add static modifier to make it work then you have a design problem. You probably have variables' scope issues in your code. Please see the example below: InputDialog is a different class that holds a reference to the table model without any static variable.

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import java.util.Date;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.table.DefaultTableModel;

public class Demo {

    private void createAndShowGUI() {

        DefaultTableModel model = new DefaultTableModel(new Object[]{"TimeStamp", "Value"}, 0) {
            @Override
            public Class<?> getColumnClass(int columnIndex) {
                switch(columnIndex) {
                    case 0: return Date.class;
                    default:  return super.getColumnClass(columnIndex);
                }
            }
        };

        final JTable table = new JTable(model);

        JButton button = new JButton("Add entry...");
        button.addActionListener(new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                new InputDialog((DefaultTableModel)table.getModel()).createAndShowGUI();
            }
        });

        JFrame frame = new JFrame("Demo");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.add(new JScrollPane(table), BorderLayout.CENTER);
        frame.add(button, BorderLayout.SOUTH);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }

    class InputDialog {

        private final DefaultTableModel model;

        public InputDialog(DefaultTableModel model) {
            this.model = model;
        }

        public void createAndShowGUI() {

            final JTextField textField = new JTextField(10);
            textField.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    model.addRow(new Object[]{new Date(), textField.getText()});
                    Window window = SwingUtilities.windowForComponent((Component)e.getSource());
                    window.dispatchEvent(new WindowEvent(window, WindowEvent.WINDOW_CLOSING));
                }
            });

            JPanel panel = new JPanel();
            panel.add(new JLabel("Please input a value and press ENTER key:"));
            panel.add(textField);

            JDialog dialog = new JDialog();
            dialog.setModal(true);
            dialog.setDefaultCloseOperation(JDialog.DISPOSE_ON_CLOSE);
            dialog.add(panel);
            dialog.pack();
            dialog.setLocationRelativeTo(null);
            dialog.setVisible(true);
        }

    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {                
                new Demo().createAndShowGUI();
            }
        });
    }
}