different JComboBoxes as editors on multiple JTable rows

[Matthew Taylor]

Objective: Use JComboBoxes within two columns of a JTable. Within each row of the table, the value of the first JComboBox will dictate what values are presented for selection within the second JComboBox.

Problem: I can't find a good way to specify a different cell editor for each row within a column. It's easy to choose an editor for the entire column, but in this case I may want to use different JComboBox options on different rows.

Sample Code: This code doesn't attempt to solve the entire problem, but shows the problem I'm running into right now. I have a debugging statement that writes out a message to the screen each time an ActionEvent occurs on a JComboBox within the first column. I'm trying to assign a unique ID to each JComboBox within each row so I can tell which one was chosen. That way I can tell which corresponding JComboBox in the second column to manipulate in response. However, every time an event is fired from the event-dispatching thread during execution, the same JComboBox is the source (it happens to always be the last one that was created).

 
import javax.swing.*;
import javax.swing.table.*;
 
import java.awt.*;
import java.awt.event.*;
import java.util.ArrayList;
import java.util.HashMap;
 
public class TestTablePanel extends JPanel {
JTable table;
MyTableModel model = new MyTableModel();
 
// values for the first column of comboboxes
String[] valueIndex = {"Coffees", "Sodas", "Beers"};
 
// values for the second column of comboboxes, dynamically 
// dependent on the value of the combobox in the first column
// on the same row
HashMap region;
    
public TestTablePanel() {
ArrayList tmp = new ArrayList();
        region = new HashMap();
        // load some sample values into the data structures
        tmp.add("Columbian"); tmp.add("Ethiopian"); tmp.add("Starbucks");
        region.put(valueIndex[0], tmp);
        tmp.clear(); tmp.add("Coke"); tmp.add("Pepsi"); tmp.add("Sprite");
        region.put(valueIndex[1], tmp);
        tmp.clear(); tmp.add("Bud"); tmp.add("Miller"); tmp.add("Guiness");
        region.put(valueIndex[2], tmp);
        
        // create table using the user-defined model
        table = new JTable(model);
 
        // Install the custom editor on the first column
        int vColIndex = 0;
        TableColumn col = table.getColumnModel().getColumn(vColIndex);
        for (int i=0; i<model.getRowCount(); i++) {
        col.setCellEditor(new JComboBoxTableCellEditor(valueIndex, i));
        }
        
        add(table);
}

    class MyTableModel extends AbstractTableModel {
        private String[] columnNames = {"Beverage", "Beverage Type"};
        private Object[][] data = {
            {"Choose", "Choose"},
            {"Choose", "Choose"},
            {"Choose", "Choose"},
            {"Choose", "Choose"},
            {"Choose", "Choose"}
        };
 
        public int getColumnCount() {
            return columnNames.length;
        }
 
        public int getRowCount() {
            return data.length;
        }
 
        public String getColumnName(int col) {
            return columnNames[col];
        }
 
        public Object getValueAt(int row, int col) {
            return data[row][col];
        }
 
        public Class getColumnClass(int c) {
        return getValueAt(0, c).getClass();
        }
 
        public boolean isCellEditable(int row, int col) {
            return true;
        }
 
        public void setValueAt(Object value, int row, int col) {
            data[row][col] = value;
            fireTableCellUpdated(row, col);
        }
    }
 
/* 
 * I'm trying to set this class up as the cell editor for the
 * third and fourth columns of the table.  I used the indexed
 * JComboBoxes so I can identify which one was changed when
 * an action event is fired.  The problem is that no matter what
 * box I choose, the ActionEvent has the same source -- the last
 * JComboBox created within this class. 
 */
public class JComboBoxTableCellEditor extends AbstractCellEditor
implements TableCellEditor {
IndexedJComboBox cBox;

/* values should be the JComboBox elements for this column,
 * id specified the JComboBox uniquely from the others for
 * event firing purposes later
public JComboBoxTableCellEditor(String[] values, int id) {
cBox = new IndexedJComboBox(values, id);
cBox.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent evt) {
System.out.println("JComboBox " + 
((IndexedJComboBox)evt.getSource()).getID() + 
" selected!");
}
});
}

public Component getTableCellEditorComponent (JTable table, Object value,
                boolean isSelected, int rowIndex, int vColIndex) {
return cBox;
}

public Object getCellEditorValue() {
return cBox.getSelectedItem();
}
}

/* used to specify which combobox is which within the model. */
public class IndexedJComboBox extends JComboBox {
int id;

public IndexedJComboBox(Object[] vals, int i) { 
super(vals);
id = i; 
}

public int getID() { return id; }
}
}

This is just the last attempt I've made at this problem. I've been working on it sporatically for about a week. Please help if you have any experience with this.

[ June 20, 2005: Message edited by: Peter Glass ]
[ June 20, 2005: Message edited by: Peter Glass ]

[Matthew Taylor]

Nevermind, I figured it out. The only way I could add a different renderer and editor for my table was to extend JTable and overwrite the getCellEditor(int row, int col) and getCellRender(int row, int col) methods.