thomasjcf21 thomasjcf21 - 4 months ago 13
Java Question

Result Set not always being shown in the JTable

I am creating an application in Java which retrieves some information from a MySQL database and then displays it in a JTable on the screen.

The code I am using to get and put the information into a DefaultListModel<> is shown below. The DefaultListModel<> is then fed to the JTable which displays the information onto the screen.

SwingWorker<Void, Void> worker = new SwingWorker< Void, Void>() {

@Override
public Void doInBackground() {

String SQL = "SELECT * FROM AddABill";

try {
Statement stmt = GlobalVars.conn.createStatement();

ResultSet rs = stmt.executeQuery(SQL);

menuOptions.clear();

while(rs.next()){

menuOptions.addElement(rs.getString(1) + " - " + rs.getString(2));
}

rs.close();
stmt.close();
}

catch (SQLException e) {
System.out.println("An Error Was Detected! :/");
}

return null;
}

@Override
public void done(){
loadingGif.setVisible(false);
}

};

worker.execute();


The issue I am having is that sometimes the information is displayed onto the screen and sometimes it isn't. Since there is no change in the query used I am assuming it is something to do with the MySQL connection.

The JTable and MenuOptions are setup like this

menuOptions = new DefaultListModel<>();
menuOptions.addElement("");

menuList = new JList<>(menuOptions);
menuList.setFont(new Font("Myriad Hebrew", Font.PLAIN, 32));
menuList.setBackground(Color.decode("#005952"));
menuList.setForeground(Color.decode("#BEC423"));
menuList.setSelectionBackground(Color.decode("#660033"));
menuList.setSelectionForeground(Color.decode("#FFFFFF"));


So the question I am wondering is how can I make sure that the information is always displayed on the screen. A picture of when it is displayed and not displayed is shown below.

Displayed:

Displayed

Not Displayed:

Not Displayed

On a final note to get the information to show I have to keep on re-running the code until it is eventually shown.

Any help is much appreciated.

Answer

@trashgod @mKorbel

Thanks for the help guys, I have solved the issue by adding the information into the table from the done() function. The code is below

SwingWorker<Void, Void> worker = new SwingWorker< Void, Void>() {

        String[] billItems = null;

        @Override
        public Void doInBackground() {

            String SQL = "SELECT * FROM AddABill";

            try {
                Statement stmt = GlobalVars.conn.createStatement();

                ResultSet rs = stmt.executeQuery(SQL);

                //Set The Cursor To Last Position
                rs.last();

                int totalRows = rs.getRow();

                billItems = new String[totalRows];

                //Set The Cursor Back To The Start
                rs.beforeFirst();

                while(rs.next()){
                    int rowNum = rs.getRow() - 1;
                    billItems[rowNum] = rs.getString(1) + " - " + rs.getString(2);
                }

                rs.close();
                stmt.close();
            }

            catch (SQLException e) {
                System.out.println("An Error Was Detected! :/");
            }

            return null;
        }

        @Override
        public void done(){
            menuOptions.clear();

            for(int i = 0; i < billItems.length; i++){
                menuOptions.addElement(billItems[i]);
            }

            loadingGif.setVisible(false);
        }

    };

Thanks,

Thomas.