JTable

[Gerald Spica]

I am trying to create a Jtable using Vectors. When I compile the code I get the following error. What is the cause of this error?
C:\j2sdk1.4.1_04\bin\dev\Table>java SimpleTableDemo
Exception in thread "main" java.lang.ClassCastException
at javax.swing.table.DefaultTableModel.justifyRows(DefaultTableModel.jav
a:238)
at javax.swing.table.DefaultTableModel.setDataVector(DefaultTableModel.j
ava:194)
at javax.swing.table.DefaultTableModel.<init>(DefaultTableModel.java:131
)
at javax.swing.JTable.<init>(JTable.java:392)
at SimpleTableDemo.<init>(SimpleTableDemo.java:29)
at SimpleTableDemo.main(SimpleTableDemo.java:70)

 import javax.swing.JTable;
import javax.swing.JScrollPane;
import javax.swing.JPanel;
import javax.swing.JFrame;
import java.awt.*;
import java.awt.event.*;
importjava.util.*;
importjava.io.*;
public class SimpleTableDemo extends JFrame {
    private boolean DEBUG = true;
   private Vectordata;
   private Vector columnNames;
    public SimpleTableDemo() throws Exception {
        super("SimpleTableDemo");
     data = new Vector();
 data.add(new Appointment("Appt 182","Suite 202","Wilson","Checkup"));
 data.add(new Appointment("Appt 183","Suite 201","Ridge","Testing"));
 data.add(new Appointment("Appt 184","Suite 200","Wilson","X-ray"));
data.add(new Appointment("Appt 185", "Suite 205","Davies","Checkup"));

       columnNames = new Vector();
       columnNames.add(new AppointmentHeader("Name", "Location", "Appointed", "Purpose"));

        final JTable table = new JTable(data, columnNames);
        table.setPreferredScrollableViewportSize(new Dimension(500, 70));
        if (DEBUG) {
            table.addMouseListener(new MouseAdapter() {
                public void mouseClicked(MouseEvent e) {
                    printDebugData(table);
                }
            });
        }
        //Create the scroll pane and add the table to it.
        JScrollPane scrollPane = new JScrollPane(table);
        //Add the scroll pane to this window.
        getContentPane().add(scrollPane, BorderLayout.CENTER);
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
    }
    private void printDebugData(JTable table) {
        int numRows = table.getRowCount();
        int numCols = table.getColumnCount();
        javax.swing.table.TableModel model = table.getModel();
        System.out.println("Value of data: ");
        for (int i=0; i < numRows; i++) {
            System.out.print("    row " + i + ":");
            for (int j=0; j < numCols; j++) {
                System.out.print("  " + model.getValueAt(i, j));
            }
            System.out.println();
        }
        System.out.println("--------------------------");
    }
    public static void main(String[] args) throws Exception {
        SimpleTableDemo frame = new SimpleTableDemo();
        frame.pack();
        frame.setVisible(true);
    }
}
 

[Ernest Friedman-Hill]

The two arguments to the JTable constructor you're using are supposed to be a Vector of Vectors of cell contents, and a Vector of Strings. You're passing, instead, a Vector of Appointment objects, and a Vector containing a single AppointmentHeader object. I can't be sure what your intention is, but I think you want to do something like (code deliberately direct and straightforward, you could certainly use loops ...

Vector rowData = new Vector();
Vector row1 = new Vector();
row1.add("Appt 182");
row1.add("Suite 202");
row1.add("Wilson");
row1.add("Checkup");
rowData.add(row1);
Vector row2 = ...
Vector columnNames = new Vector();
columnNames.add("Name");
columnNames.add("Location");
columnNames.add ...
JTable table = new JTable(rowData, columnNames);

If you want to take the data directly from your business objects, then you need to write your own custom TableModel.

[F A H A D]

hi!
u have to add the field in the Table by using 2D Array or set the vector in the Table. If u want to add the field dynamically u have to uise the DefaultTableModel. I suggest u to use DefaultTableModel.
Take Care
Bye...