Highlighting a column header of a JTable

highlight, java, jtable, jtableheader, swing

Solution

The basic issue I had was there was no connection between the table header and the selection change. In fact, the header is really clever with it's repaints...

I ended up providing my own header, which attached a listener to the table's selection model and repainted the header on the selection changed.

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.EventQueue;
import java.util.List;
import javax.swing.Icon;
import javax.swing.JFrame;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.RowSorter;
import javax.swing.RowSorter.SortKey;
import static javax.swing.SortOrder.ASCENDING;
import static javax.swing.SortOrder.DESCENDING;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ListSelectionEvent;
import javax.swing.event.ListSelectionListener;
import javax.swing.table.DefaultTableCellRenderer;
import javax.swing.table.DefaultTableModel;
import javax.swing.table.JTableHeader;

public class TestColumnHighlight {

    public static void main(String[] args) {
        new TestColumnHighlight();
    }

    public TestColumnHighlight() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                }

                JTable table = new JTable();
                DefaultTableModel model = new DefaultTableModel(
                                new Object[]{"abc", "def", "ghi", "jkl"},
                                0);

                model.addRow(new Object[]{0, 0, 0, 0});
                model.addRow(new Object[]{0, 0, 0, 0});
                model.addRow(new Object[]{0, 0, 0, 0});
                model.addRow(new Object[]{0, 0, 0, 0});
                model.addRow(new Object[]{0, 0, 0, 0});

                table.setModel(model);
                table.setTableHeader(new CustomTableHeader(table));
                table.getTableHeader().setDefaultRenderer(new ColumnHeaderRenderer());

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setLayout(new BorderLayout());
                frame.add(new JScrollPane(table));
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class CustomTableHeader extends JTableHeader {

        public CustomTableHeader(JTable table) {
            super();
            setColumnModel(table.getColumnModel());
            table.getColumnModel().getSelectionModel().addListSelectionListener(new ListSelectionListener() {
                @Override
                public void valueChanged(ListSelectionEvent e) {
                    repaint();
                }
            });
        }

        @Override
        public void columnSelectionChanged(ListSelectionEvent e) {
            repaint();
        }

    }

    public class ColumnHeaderRenderer extends DefaultTableHeaderCellRenderer {

        @Override
        public Component getTableCellRendererComponent(JTable table, Object value, boolean selected, boolean focused, int row, int column) {
            super.getTableCellRendererComponent(table, value, selected, focused, row, column);

            int selectedColumn = table.getSelectedColumn();
            System.out.println("Selected " + selectedColumn + "-" + column);
            if (selectedColumn == column) {
                Color bg = table.getSelectionBackground();
                setBackground(bg);
                setOpaque(true);
            } else {
                setOpaque(false);
            }

            return this;
        }

    }

    public class DefaultTableHeaderCellRenderer extends DefaultTableCellRenderer {

        public DefaultTableHeaderCellRenderer() {
            setHorizontalAlignment(CENTER);
            setHorizontalTextPosition(LEFT);
            setVerticalAlignment(BOTTOM);
            setOpaque(false);
        }

        @Override
        public Component getTableCellRendererComponent(JTable table, Object value,
                        boolean isSelected, boolean hasFocus, int row, int column) {
            super.getTableCellRendererComponent(table, value,
                            isSelected, hasFocus, row, column);
            JTableHeader tableHeader = table.getTableHeader();
            if (tableHeader != null) {
                setForeground(tableHeader.getForeground());
            }
            setIcon(getIcon(table, column));
            setBorder(UIManager.getBorder("TableHeader.cellBorder"));
            return this;
        }

        protected Icon getIcon(JTable table, int column) {
            SortKey sortKey = getSortKey(table, column);
            if (sortKey != null && table.convertColumnIndexToView(sortKey.getColumn()) == column) {
                switch (sortKey.getSortOrder()) {
                    case ASCENDING:
                        return UIManager.getIcon("Table.ascendingSortIcon");
                    case DESCENDING:
                        return UIManager.getIcon("Table.descendingSortIcon");
                }
            }
            return null;
        }

        protected SortKey getSortKey(JTable table, int column) {
            RowSorter rowSorter = table.getRowSorter();
            if (rowSorter == null) {
                return null;
            }

            List sortedColumns = rowSorter.getSortKeys();
            if (sortedColumns.size() > 0) {
                return (SortKey) sortedColumns.get(0);
            }
            return null;
        }
    }
}

Problem

i'm currently building a little JTable, and want to highlight the column header (and row headers - the row-header part is actually working) when a cell is selected to make it easier to find the associated names with this cell. Here is a picture: I already tried switching out the renderer for the header with this: ``` table.getTableHeader().setDefaultRenderer(new ColumnHeaderRenderer()); ``` But it's only called when i click on the header and always says isSelected is false. This is the code i use for the row-names, including the highlight inside the renderer - code is not by me, i just modified it a little: ``` /* * Use a JTable as a renderer for row numbers of a given main table. * This table must be added to the row header of the scrollpane that * contains the main table. */ public class RowNameTable extends JTable implements ChangeListener, PropertyChangeListener { private JTable main; public RowNameTable(JTable table) { main = table; main.addPropertyChangeListener(this); setFocusable(false); setAutoCreateColumnsFromModel(false); setModel(main.getModel()); setSelectionModel(main.getSelectionModel()); TableColumn column = new TableColumn(); column.setHeaderValue(" "); addColumn(column); column.setCellRenderer(new RowNameRenderer(main)); getColumnModel().getColumn(0).setPreferredWidth(table.getColumnModel().getColumn(0).getPreferredWidth()); setPreferredScrollableViewportSize(getPreferredSize()); } @Override public void addNotify() { super.addNotify(); Component c = getParent(); // Keep scrolling of the row table in sync with the main table. if (c instanceof JViewport) { JViewport viewport = (JViewport) c; viewport.addChangeListener(this); } } /* * Delegate method to main table */ @Override public int getRowCount() { return main.getRowCount(); } @Override public int getRowHeight(int row) { return main.getRowHeight(row); } /* * This table does not use any data from the main TableModel, * so just return a value based on the row parameter. */ @Override public Object getValueAt(int row, int column) { return Integer.toString(row + 1); } /* * Don't edit data in the main TableModel by mistake */ @Override public boolean isCellEditable(int row, int column) { return false; } // // Implement the ChangeListener // public void stateChanged(ChangeEvent e) { // Keep the scrolling of the row table in sync with main table JViewport viewport = (JViewport) e.getSource(); JScrollPane scrollPane = (JScrollPane) viewport.getParent(); scrollPane.getVerticalScrollBar().setValue(viewport.getViewPosition().y); } // // Implement the PropertyChangeListener // public void propertyChange(PropertyChangeEvent e) { // Keep the row table in sync with the main table if ("selectionModel".equals(e.getPropertyName())) { setSelectionModel(main.getSelectionModel()); } if ("model".equals(e.getPropertyName())) { setModel(main.getModel()); } } /* * Borrow the renderer from JDK1.4.2 table header */ private static class RowNameRenderer extends DefaultTableCellRenderer { private JTable main; public RowNameRenderer(JTable main) { this.main = main; setHorizontalAlignment(JLabel.CENTER); } @Override public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column) { if (table != null) { JTableHeader header = table.getTableHeader(); if (header != null) { setForeground(header.getForeground()); setBackground(header.getBackground()); setFont(header.getFont()); } } if (isSelected) { setFont(getFont().deriveFont(Font.BOLD)); } setText((value == null) ? "" : main.getColumnName(row)); setBorder(UIManager.getBorder("TableHeader.cellBorder")); return this; } } } ``` And here we have the relevant part to create the table: ``` costTableModel = new CostTableModel(costCalc); table = new JTable(costTableModel); table.setPreferredScrollableViewportSize(table.getPreferredSize()); table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF); table.setCellSelectionEnabled(true); scrollPane = new JScrollPane(table); RowNameTable nameTable = new RowNameTable(table); scrollPane.setRowHeaderView(nameTable); ``` And the class costTableModel, just for completeness sake: ``` public class CostTableModel extends AbstractTableModel { private CostCalculator costCalc; public CostTableModel(CostCalculator costCalc) { this.costCalc = costCalc; } @Override public int getRowCount() { return costCalc.getPersonsList().size(); } @Override public int getColumnCount() { return costCalc.getPersonsList().size(); } @Override public String getColumnName(int col) { return costCalc.getPersonsList().get(col).getName(); } @Override public Object getValueAt(int rowIndex, int columnIndex) { Person debtor = costCalc.getPersonsList().get(rowIndex); Person debtee = costCalc.getPersonsList().get(columnIndex); return costCalc.getAmountOwed(debtor, debtee); } @Override public Class getColumnClass(int c) { return getValueAt(0, c).getClass(); } } ``` Thank you for your help in advance!

Original source