Question

I’m still struggling with a JTable that should be automatically updated.

The situation is as follows:
I instantiate MyTable (extends JTable), and set it in my UI class (MyView). The MyTable class takes the UI class and an instance of the class that contains logic as parameters):

...
private JPanel createTablePanel() {
    tablePanel = new JPanel();
    myTable = new MyTable(this,mymeth);
    setMyTable(myTable);
    JScrollPane scrollPane = new JScrollPane(getMyTable());
    tablePanel.add(scrollPane);
    return tablePanel;
}

MyTable itself looks like below. An extension of AbstractTableModel (MyTableModel) is set to it. An extension of TableModelListener is set to the model. And finally an extension of ListSelectionListener is set to the model’s SelectionModel.

public class MyTable extends JTable implements TableModelListener
{

public MyTable(MyView myView, MyMethods mymeth)
{

    AbstractTableModel tableModel = new MyTableModel(mymeth);
    setModel(tableModel);
    getModel().addTableModelListener(new MyTableModelListener());
    setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
    setCellSelectionEnabled(true);
    getColumnModel().getSelectionModel().addListSelectionListener(new MyTableSelectionListener(this, mymeth, myView));
    setPreferredScrollableViewportSize(this.getPreferredSize());

}

}

Let’s have a quick look at the model’s constructor.

public MyTableModel(MyMethods mymeth) {
    dataObject = new MyData(mymeth);
    myData = dataObject.getMyData();
    colTitles = dataObject.getColTitles();
}

MyData compiles the data for the table: A Vector<Vector<Object>>, that consists of three Vector<Object>s (the table data) and a String[] (The column titles). The data itself comes from a graph via mymeth, the logic class’ instance.

Whenever a table column is clicked, a popup (i.e. JOptionPane) object is instantiated, which presents a selection of values for the 3rd row in the selected column. The user chooses a value and the value is set to the data model. Note the way the table is updated after that.

public MyOptionPane(int i, MyMethods mymeth, MyView myView) {
    this.view = myView;
    String sourceString = mymeth.getSourceString(i); // Gets a String from a
String[]. In this Array, the order is the same as in the table.
    String tag = null;
    tag = (String) JOptionPane.showInputDialog(this, "Choose a tag for \"" + sourceString + "\"", "String tagging" , JOptionPane.PLAIN_MESSAGE, null, myView.getTags().toArray(), myView.getTags().get(0));
    mymeth.setTag(i, tag);

    // This is where fireTableDataChanged() didn't work, but this did
            MyTableModel model = new MyTableModel(mymeth); // New model instance
    view.getMyTable().setModel(model); // reset new model to table
}

This works. However, from what I’ve read I shold be able to simply call fireTableDataChanged() on the model and the table should update itself. However, this doesn’t work. User kleopatra has commented to an answer in a previous post:

do not call any of the model’s fireXX methods from any code external to the model.
Instead implement the model to do so when anything changed

So: Can I call fireTableDataChanged() within such a structure at all? And if so, where and how?

Thanks in advance for all pieces of enlightenment!

Answer 1

from what I’ve read I shold be able to simply call fireTableDataChanged() on the model and the table should update itself

Your program doesn’t invoke the fireXXX methods on the model. The TableModel itself is responsible for invoking these methods whenever any of the data in the model is changed. Look at the Creating a Table Model example from the Swing tutorial. The setValueAt(…) method shows how to invoke the appropriate fireXXX method.

If you create a completely new TableModel, then you need to use the setModel() method.

Kleopatra’s comment was that all fireXXX methods showed be invoked from within the TableModel class itself. If you want to understand how this is done, then take a look at the source code for the DefaultTableModel. If has example of when you would invoke the fireTableDataChanged() method along with the other fireXXX methods.