JTable中JComboBox的可用性功能

Question

I'm trying to build a table which includes JComboBoxes as both the renderer and editor components. This mostly works fine, however there are two things I can't seem to solve.

1. Tabbing between cells should make the JComboBox active
2. Clicking the drop-down arrow should immediately open the option list

Regarding 1, the editable combo should place focus within the embedded text field, the fixed combo should allow the down arrow to open the list of options.

Regarding 2, I find that this sometimes works depending on what other cell is currently active, but other times I have to double click. I cannot make this behaviour consistent.

For convenience I have included a clear example which (I believe) uses the recommended approach for embedding JComboBoxes within Jtables.

Thank you for constructive advice.

import java.awt.Component;
import java.util.*;
import javax.swing.*;
import javax.swing.table.*;

public class TableCombos
{
    public static void main(String[] args)
    {
        JFrame frame = new JFrame("Frame");
        frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        AbstractTableModel model = new DefaultTableModel()
        {
            String[] columnHeaders = new String[]{"label", "combo-edit", "combo-fixed"};
            Class<?>[] columnClasses = new Class<?>[]{String.class, Double.class, Double.class};
            List<Object[]> data = new ArrayList<>();
            {
                data.add(new Object[]{"row 1", 1.0d, 2.0d});
                data.add(new Object[]{"row 2", 2.0d, 3.0d});
            }

            @Override
            public int getColumnCount()
            {
                return columnHeaders.length;
            }

            @Override
            public boolean isCellEditable(int row, int column)
            {
                return column != 0;
            }

            @Override
            public int getRowCount()
            {
                if (data == null) // race condition
                    return 0;
                return data.size();
            }

            @Override
            public Object getValueAt(int row, int column)
            {
                return data.get(row)[column];
            }

            @Override
            public void setValueAt(Object aValue, int row, int column)
            {
                data.get(row)[column] = aValue;
            }

            @Override
            public Class<?> getColumnClass(int column)
            {
                return columnClasses[column];
            }

            @Override
            public String getColumnName(int column)
            {
                return columnHeaders[column];
            }
        };

        JTable table = new JTable(model);
        table.setSurrendersFocusOnKeystroke(true);

        TableColumn c1 = table.getColumnModel().getColumn(1);
        TableColumn c2 = table.getColumnModel().getColumn(2);

        JComboBox<Double> editorComboEditable = new JComboBox<>(new Double[]{1.0d, 2.0d, 3.0d});
        editorComboEditable.setEditable(true);
        c1.setCellEditor(new DefaultCellEditor(editorComboEditable));
        c2.setCellEditor(new DefaultCellEditor(new JComboBox<>(new Double[]{1.0d, 2.0d, 3.0d})));

        final JComboBox<Double> rendererComboEditable = new JComboBox<>(new Double[]{1.0d, 2.0d, 3.0d});
        rendererComboEditable.setEditable(true);
        final JComboBox<Double> rendererComboFixed = new JComboBox<>(new Double[]{1.0d, 2.0d, 3.0d});
        c1.setCellRenderer(new TableCellRenderer()
        {
            @Override
            public Component getTableCellRendererComponent(JTable t, Object value, boolean isSelected, boolean hasFocus, int row, int column)
            {
                rendererComboEditable.setSelectedItem(value);
                return rendererComboEditable;
            }
        });
        c2.setCellRenderer(new TableCellRenderer()
        {
            @Override
            public Component getTableCellRendererComponent(JTable t, Object value, boolean isSelected, boolean hasFocus, int row, int column)
            {
                rendererComboFixed.setSelectedItem(value);
                return rendererComboFixed;
            }
        });

        frame.getContentPane().add(new JScrollPane(table));

        frame.pack();
        frame.setVisible(true);
    }
}

Answer 1

Both of your issues be resolved by overriding the DefaultCellEditor#isCellEditable method and returning true

You may need to set JTable#setSurrendersFocusOnKeystroke to true as well

Update

The short answer is "It's messy". The long answer is "it's very messy"

I did a "continuos editing" process some time back. Basically, I overrode the Enter and Tab key bindings.

What I'd did was basically stop any active cell editor, take note of the current cell and then tried to finding the next editable cell, looping back around to the start (cell 0x0) if required.

When I found a editable cell, I called JTable#esitCellAt to start editing the cell.

To get the popup to be visible when the cell starts editing, you will need to override the addNotify method of the JComboBox and, using SwingUtilities#invokeLater , set the popup visible