Linked ComboBox JTable Cell Editors

Question

I have a table with two comboBox columns. The combo box in the first column always has the same values. This is pretty simple:

jTableEditTransaction.getColumnModel().getColumn(0).setCellEditor(new DefaultCellEditor(accountClassComboBox));

The next bit is trickier: I want the values in the second column to depend on which value is selected in the first column, so each row will have different values. Can I assign an editor to a specific cell rather than to an entire column?

Answer 1

You don't want a separate editor object for cells, but instead really want one single editor for the column. What needs to change is the data held by the cell and displayed by the editor. This data can be cell specific and coded for in your editor. You'll likely want to extend the DefaultCellEditor class to allow you to do this.

For example, something like this perhaps:

import java.awt.Component;
import java.util.HashMap;
import java.util.Map;
import javax.swing.*;
import javax.swing.table.DefaultTableModel;

public class LinkedCombBoxEditors extends JPanel {
   public static final String[] DAY_TYPE = {"Weekday", "Weekend"};
   private static final String[] COL_NAMES = {"Day Type", "Day"};
   private Map<String, DefaultComboBoxModel<String>> keyMap = new HashMap<>();
   private JComboBox<String> innerEditor = new JComboBox<>();

   public LinkedCombBoxEditors() {
      DefaultComboBoxModel<String> cModel = new DefaultComboBoxModel<>();
      cModel.addElement("Monday");
      cModel.addElement("Tuesday");
      cModel.addElement("Wednesday");
      cModel.addElement("Thursday");
      cModel.addElement("Friday");
      keyMap.put(DAY_TYPE[0], cModel);

      cModel = new DefaultComboBoxModel<>();
      cModel.addElement("Saturday");
      cModel.addElement("Sunday");
      keyMap.put(DAY_TYPE[1], cModel);

      DefaultTableModel model = new DefaultTableModel(COL_NAMES, 4);
      JComboBox<String> comboBox0 = new JComboBox<>(DAY_TYPE);
      JTable table = new JTable(model);
      table.getColumnModel().getColumn(0).setCellEditor(new DefaultCellEditor(comboBox0));
      table.getColumnModel().getColumn(1).setCellEditor(new ComboEditor1(innerEditor));

      add(new JScrollPane(table));
   }

   private class ComboEditor1 extends DefaultCellEditor {

      private ComboBoxModel<String> emptyModel = new DefaultComboBoxModel<>();

      public ComboEditor1(JComboBox<String> innerEditor) {
         super(innerEditor);
      }

      @Override
      public Component getTableCellEditorComponent(JTable table, Object value,
            boolean isSelected, int row, int column) {
         Component editorComp = super.getTableCellEditorComponent(table, value, isSelected, row, column);
         JComboBox<String> comboBox = (JComboBox<String>)editorComp; 
         Object item = table.getValueAt(row, 0);
         if (item != null) {
            DefaultComboBoxModel<String> comboModel = keyMap.get(item);
            comboBox.setModel(comboModel);
         } else {
            comboBox.setModel(emptyModel);
         }
         // DefaultComboBoxModel<String> model = new 
         return editorComp;
      }
   }

   private static void createAndShowGui() {
      LinkedCombBoxEditors mainPanel = new LinkedCombBoxEditors();

      JFrame frame = new JFrame("LinkedCombBoxEditors");
      frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
      frame.getContentPane().add(mainPanel);
      frame.pack();
      frame.setLocationByPlatform(true);
      frame.setVisible(true);
   }

   public static void main(String[] args) {
      SwingUtilities.invokeLater(new Runnable() {
         public void run() {
            createAndShowGui();
         }
      });
   }
}