Populating jTable using database data

So, you need some way to “tell” the table that the model has been loaded. You could use a listener call back mechanism, but it might be easier to use a SwingWorker instead.

This will allow you to make a call to the database in a background thread and when it’s finished, update the UI from within the EDT.

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.util.Vector;
import java.util.concurrent.ExecutionException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.swing.JTable;
import javax.swing.SwingWorker;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.TableModel;
import sun.applet.Main;

public class DataLoadWorker extends SwingWorker<TableModel, TableModel> {

    private final JTable table;

    public DataLoadWorker(JTable table) {
        this.table = table;
    }

    @Override
    protected TableModel doInBackground() throws Exception {
        Vector data = new Vector();
        Vector columns = new Vector();
        PreparedStatement ps = null;
        ResultSet rs = null;
        try {
            String stmt = "SELECT * FROM APP.DATAVAULT";
            ps = Main.getPreparedStatement(stmt);
            rs = ps.executeQuery();
            ResultSetMetaData md = rs.getMetaData();
            int columnCount = md.getColumnCount();
            //store column names  
            for (int i = 1; i <= columnCount; i++) {
                columns.add(md.getColumnName(i));
            }

            columns.ensureCapacity(columnCount);

            Vector row;
            while (rs.next()) {

                row = new Vector(columnCount);
                for (int i = 1; i <= columnCount; i++) {
                    row.add(rs.getString(i));
                }
                data.add(row);

                //Debugging                
            }

            // List.setModel(tableModel);

        } finally {
            try {
                ps.close();
            } catch (Exception e) {
            }
            try {
                rs.close();
            } catch (Exception e) {
            }
        }

        DefaultTableModel tableModel = new DefaultTableModel(data, columns);
        return tableModel;
    }

    @Override
    protected void done() {
        try {
            TableModel model = get();
            table.setModel(model);
        } catch (InterruptedException | ExecutionException ex) {
            ex.printStackTrace();
        }
    }
}

You’re example won’t work either.

The Vectors columns and data are declared withing the context of the try-catch, which means they won’t be visible to the remainder of the method, so DefaultTableModel tableModel = new DefaultTableModel(data, columns); won’t compile.

You should be, at the very least, dumping the stack trace of any exceptions, it will help you find where the actually error is, so instead of System.out.println(e.getMessage());, you should use e.printStackTrace();. A better solution is to use the Logger either from the JDK or a third party logger like log4j.

You are also resources, that is, if you open, you should close it. While you do call ps.close() and rs.close(), if, for what ever reason, an exception occurs, they will not be called, leaving resources open.

Add these to the finally block of your try-catch to ensure that they are closed and make all best efforts to close them.