How to Get a Defaulttablemodel Object's Data into a Subclass of Defaulttablemodel

How to get a DefaultTableModel object's data into a subclass of DefaultTableModel

Here is an example that shows how to read the data from the ResultSet and implement the getColumnClass(...) method in your own custom DefaultTableModel:

import java.awt.*;
import java.sql.*;
import java.util.*;
import javax.swing.*;
import javax.swing.table.*;

public class TableFromDatabase extends JFrame
{
    public TableFromDatabase()
    {
        Vector<Object> columnNames = new Vector<Object>();
        Vector<Object> data = new Vector<Object>();

        try
        {
            //  Connect to an Access Database

            String driver = "sun.jdbc.odbc.JdbcOdbcDriver";
//            String url = "jdbc:odbc:???";  // if using ODBC Data Source name
            String url =
                "jdbc:odbc:Driver={Microsoft Access Driver (*.mdb)};DBQ=c:/directory/???.mdb";
            String userid = "";
            String password = "";

            Class.forName( driver );
            Connection connection = DriverManager.getConnection( url, userid, password );

            //  Read data from a table

            String sql = "Select * from ???";
            Statement stmt = connection.createStatement();
            ResultSet rs = stmt.executeQuery( sql );
            ResultSetMetaData md = rs.getMetaData();
            int columns = md.getColumnCount();

            //  Get column names

            for (int i = 1; i <= columns; i++)
            {
                columnNames.addElement( md.getColumnLabel(i) );
            }

            //  Get row data

            while (rs.next())
            {
                Vector<Object> row = new Vector<Object>(columns);

                for (int i = 1; i <= columns; i++)
                {
                    row.addElement( rs.getObject(i) );
                }

                data.addElement( row );
            }

            rs.close();
            stmt.close();
            connection.close();
        }
        catch(Exception e)
        {
            System.out.println( e );
        }

        //  Create table with database data

        DefaultTableModel model = new DefaultTableModel(data, columnNames)
        {
            @Override
            public Class getColumnClass(int column)
            {
                for (int row = 0; row < getRowCount(); row++)
                {
                    Object o = getValueAt(row, column);

                    if (o != null)
                    {
                        return o.getClass();
                    }
                }

                return Object.class;
            }
        };

        JTable table = new JTable( model );
        JScrollPane scrollPane = new JScrollPane( table );
        add( scrollPane );

        JPanel buttonPanel = new JPanel();
        add( buttonPanel, BorderLayout.SOUTH );
    }

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

By overriding the getColumnClass(...) method you will now see number formatted right aligned and if you ever need to sort the data it will work properly since the column will be sorted based on a numeric value not a String value.

I want to add a CheckBox to each row.

So now you have two options:

1. Modify the above code so that the "columnNames" Vector contains another header name for the check box column and add Boolean.FALSE to each "row" Vector as you iterate through the ResultSet.

2. Use the above TableModel as is (or use the DbUtils TableModel) and then create a wrapper TableModel that will add a check box column to any existing TableModel. Check out: How to add checkbox in Jtable populated using rs2xml for an example of this approach.

How to subclass DefaultTableModel and change its dataVector

You have to override the getValueAt(...) method:

@Override
public Object getValueAt(int row, int column) {
    DataHolder data = dataVector_.get(row);
    switch(column) {
        case 0: return data.month;
        case 1: return data.day;
        case 2: return data.year;
        default: return null;
    }

How to Retrieve JTable Data as an Array

I take that back, on 2nd thoughts, you dont need any typecasting - TableModel is an interface that has all the 3 method calls you need. :)

Summary: Get the model for the table, check its class and typecast it to appropriate class (Abstract or Default TableModel), and use its methods to load a newly created array. Some psuedoCode:

public Object[][] getTableData (JTable table) {
    DefaultTableModel dtm = (DefaultTableModel) table.getModel();
    int nRow = dtm.getRowCount(), nCol = dtm.getColumnCount();
    Object[][] tableData = new Object[nRow][nCol];
    for (int i = 0 ; i < nRow ; i++)
        for (int j = 0 ; j < nCol ; j++)
            tableData[i][j] = dtm.getValueAt(i,j);
    return tableData;
}

Your headers should not have changed by user-edits. Hope that helps. Regards, - M.S.

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