How to add data to JTable created in design mode?

Question

I created an initial JFrame that contains a table with three columns, as shown below:

This JFrame was created in design mode, and so now in the panel's constructor, I want to load some data so when the user selects to open this JFrame, the data is loaded.

My column data types are Object (generally 'Status' is for an image representing the status of the share - active or inactive), String for the share's name and integer for the number of active clients connected to that share.

My question is, how to I add rows to a JTable via code?

Answer 1

In a simplified way (can be improved):

class MyModel extends AbstractTableModel{

    private ArrayList<Register> list = new ArrayList<Register>();

    @Override
    public int getColumnCount() {
        return 3;
    }

    @Override
    public int getRowCount() {
        return list.size();
    }

    @Override
    public Object getValueAt(int rowIndex, int columnIndex) {
        Register r = list.get(rowIndex);
        switch (columnIndex) {
        case 0: return r.status; 
        case 1: return r.name;
        case 2: return r.clients; 
        }
            return null;
    }

    public void addRegister(String status, String name, String clients){
        list.add(new Register(status, name, clients));
        this.fireTableDataChanged();
    }

    class Register{
        String status;
        String name;
        String clients;

        public Register(String status, String name, String clients) {
            this.status = status;
            this.name = name;
            this.clients = clients;
        }
    }

}

Then, in the panel's constructor:

MyTableModel mtm = new MyTableModel();
yourtable.setModel(mtm);

And for add a line:

mtm.addRegister("the status","the name","the client(s)");

EDIT:

To alter a column's header name:

TableColumn statusColumn = yourtable.getColumnModel().getColumn(0); 
statusColumn.setHeaderValue("Status");

Answer 2

• JTable has two levels (as you posted printscreen) talking about view,

• there is (hidden) XxxTableModel which stores the values,

• in the XxxTableModel you can to call myTableModel#addRow

simple example

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.table.*;

public class RemoveAddRows extends JFrame {

    private static final long serialVersionUID = 1L;
    private Object[] columnNames = {"Type", "Company", "Shares", "Price"};
    private Object[][] data = {
        {"Buy", "IBM", new Integer(1000), new Double(80.50)},
        {"Sell", "MicroSoft", new Integer(2000), new Double(6.25)},
        {"Sell", "Apple", new Integer(3000), new Double(7.35)},
        {"Buy", "Nortel", new Integer(4000), new Double(20.00)}
    };
    private JTable table;
    private DefaultTableModel model;

    public RemoveAddRows() {

        model = new DefaultTableModel(data, columnNames) {

            private static final long serialVersionUID = 1L;

            @Override
            public Class getColumnClass(int column) {
                return getValueAt(0, column).getClass();
            }
        };
        table = new JTable(model) {

            private static final long serialVersionUID = 1L;

            @Override
            public Component prepareRenderer(TableCellRenderer renderer, int row, int column) {
                Component c = super.prepareRenderer(renderer, row, column);
                int firstRow = 0;
                int lastRow = table.getRowCount() - 1;
                int width = 0;
                if (row == lastRow) {
                    ((JComponent) c).setBackground(Color.red);
                } else if (row == firstRow) {
                    ((JComponent) c).setBackground(Color.blue);
                } else {
                    ((JComponent) c).setBackground(table.getBackground());
                }
                /*if (!isRowSelected(row)) {
                String type = (String) getModel().getValueAt(row, 0);
                c.setBackground("Buy".equals(type) ? Color.GREEN : Color.YELLOW);
                }
                if (isRowSelected(row) && isColumnSelected(column)) {
                ((JComponent) c).setBorder(new LineBorder(Color.red));
                }*/
                return c;
            }
        };
        table.setPreferredScrollableViewportSize(table.getPreferredSize());
        JScrollPane scrollPane = new JScrollPane(table);
        add(scrollPane);
        JButton button1 = new JButton("Remove all rows");
        button1.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent arg0) {
                if (model.getRowCount() > 0) {
                    for (int i = model.getRowCount() - 1; i > -1; i--) {
                        model.removeRow(i);
                    }
                }
                System.out.println("model.getRowCount() --->" + model.getRowCount());
            }
        });
        JButton button2 = new JButton("Add new rows");
        button2.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent arg0) {
                Object[] data0 = {"Buy", "IBM", new Integer(1000), new Double(80.50)};
                model.addRow(data0);
                Object[] data1 = {"Sell", "MicroSoft", new Integer(2000), new Double(6.25)};
                model.addRow(data1);
                Object[] data2 = {"Sell", "Apple", new Integer(3000), new Double(7.35)};
                model.addRow(data2);
                Object[] data3 = {"Buy", "Nortel", new Integer(4000), new Double(20.00)};
                model.addRow(data3);
                System.out.println("model.getRowCount() --->" + model.getRowCount());
            }
        });
        JPanel southPanel = new JPanel();
        southPanel.add(button1);
        southPanel.add(button2);
        add(southPanel, BorderLayout.SOUTH);
    }

    public static void main(String[] args) {
        RemoveAddRows frame = new RemoveAddRows();
        frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
        frame.pack();
        frame.setLocationRelativeTo(null);
        frame.setVisible(true);
    }
}