How to make a JComboBox table editor have the design of an ordinary JComboBox?

Question

I have a JComboBox used as an editor in a JTable. In the picture you can see them in the column labeled Produs. I would like to use the design of the stand-alone JComboBox in the grid cells, particularly the right part of the combo box where the triangle is missing from the grid cells, so a user will know that the grid cells are combo boxes without having to click on one of them. How can I apply the design of the JComboBox (IsBackFlush) to the JComboBoxes in the grid?

Essentially, how can I design comboBox2 based on the design of comboBox1? Thanks.

Answer 1

Working from this complete example as a common frame of reference, note how the appearance of unselected cells in the ITEM_COL column is due to the default renderer. The arrow button typical of a stand-alone JComboBox only appears when the cell's editor is evoked, as by clicking on the cell or pressing Space when the cell is selected. You can add a triangle in a custom renderer:

final JComboBox combo = new JComboBox(items);
TableColumn col = table.getColumnModel().getColumn(ITEM_COL);
col.setCellRenderer(new DefaultTableCellRenderer(){

    @Override
    public Component getTableCellRendererComponent(JTable table, Object value,
            boolean isSelected, boolean hasFocus, int row, int column) {
        JLabel label = (JLabel) super.getTableCellRendererComponent(table,
            value, isSelected, hasFocus, row, column);
        label.setIcon(UIManager.getIcon("Table.descendingSortIcon"));
        return label;
    }
});

Addendum: A more complete example due to @aterai is seen here.

Answer 2

In the spirit of moving forward I was going to post the solution that I was talking about earlier. This solution actually uses comboBox as a renderer. So it will look the same as a real comboBox in any LAF. The problem is that the text is squished, so I like trashgod's implementation better.

import java.awt.*;
import java.awt.event.*;
import java.util.List;
import java.util.ArrayList;
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;

public class TableComboBoxByRow extends JFrame
{
    List<TableCellEditor> editors = new ArrayList<TableCellEditor>(3);

    public TableComboBoxByRow()
    {
        // Create the editors to be used for each row

        String[] items1 = { "Red", "Blue", "Green" };
        JComboBox comboBox1 = new JComboBox( items1 );
        DefaultCellEditor dce1 = new DefaultCellEditor( comboBox1 );
        editors.add( dce1 );

        String[] items2 = { "Circle", "Square", "Triangle" };
        JComboBox comboBox2 = new JComboBox( items2 );
        DefaultCellEditor dce2 = new DefaultCellEditor( comboBox2 );
        editors.add( dce2 );

        String[] items3 = { "Apple", "Orange", "Banana" };
        JComboBox comboBox3 = new JComboBox( items3 );
        DefaultCellEditor dce3 = new DefaultCellEditor( comboBox3 );
        editors.add( dce3 );

        //  Create the table with default data

        Object[][] data =
        {
            {"Color", "Red"},
            {"Shape", "Square"},
            {"Fruit", "Banana"},
            {"Plain", "Text"}
        };
        String[] columnNames = {"Type","Value"};
        DefaultTableModel model = new DefaultTableModel(data, columnNames);
        JTable table = new JTable(model)
        {
            //  Determine editor to be used by row
            public TableCellEditor getCellEditor(int row, int column)
            {
                int modelColumn = convertColumnIndexToModel( column );

                if (modelColumn == 1 && row < 3)
                    return editors.get(row);
                else
                    return super.getCellEditor(row, column);
            }
        };

        JScrollPane scrollPane = new JScrollPane( table );
        getContentPane().add( scrollPane );
        table.getColumnModel().getColumn(1).setCellRenderer(new ComboBoxRenderer() );
    }

    class ComboBoxRenderer extends JComboBox implements TableCellRenderer
    {

        public ComboBoxRenderer()
        {
            setBorder(new EmptyBorder(0, 0, 0, 0));
        }

        public Component getTableCellRendererComponent(
            JTable table, Object value, boolean isSelected,
            boolean hasFocus, int row, int column)
        {
//          setFocusable(false);
            removeAllItems();
            addItem( value );
            return this;
        }
    }

    public static void main(String[] args)
    {
        TableComboBoxByRow frame = new TableComboBoxByRow();
        frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
        frame.pack();
        frame.setVisible(true);
    }
}