How to outline selected cells during drag and drop in the jtable

Question

Hi,
I have spent a lot of time to find out how to outline selected cells during drag in the jtable, but I did not find the answer.
Can anybody give me a tip, where to read more about this problem or even better, give an example...
I have the following situation:
1.Table has 10 rows and 10 columns
2.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION) and setCellSelectionEnabled(true)
3.user select 5 cells in 4th row (for example cell45,cell46,cell47,cell48 and cell49)
4.user starts dragging. During dragging an outline should be drawn. Outline should be a rectangular with width of 5 cells and height of one cell. Outline should move according to the mouse position.
5.rectangular disappears when dropped
Regards,
Primoz

Answer 1

In "createTransferable" you can create a drag image
which you can paint in "dragOver" and clear in "drop" method of DropTarget :
package dnd;
* DragDropJTableCellContents.java
import javax.swing.*;
import javax.swing.border.*;
import javax.swing.table.*;
import java.awt.*;
import java.awt.datatransfer.*;
import java.awt.dnd.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import java.io.IOException;
public class DragDropJTableCellContents extends JFrame {
    public DragDropJTableCellContents() {
        setTitle("Drag and Drop JTable");
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        getContentPane().add(createTable("JTable"), BorderLayout.CENTER);
        setSize(400, 300);
        setLocationRelativeTo(null);
    private JPanel createTable(String tableId) {
        DefaultTableModel model = new DefaultTableModel();
        for (int i = 0; i < 10; i++) {
            model.addColumn("Column "+i);
        for (int i = 0; i < 10; i++) {
            String[] rowData = new String[10];
            for (int j = 0; j < 10; j++) {
                rowData[j] = tableId + " " + i + j;
            model.addRow(rowData);
        JTable table = new JTable(model);
        table.getTableHeader().setReorderingAllowed(false);
        table.setSelectionMode(ListSelectionModel.SINGLE_INTERVAL_SELECTION);
        table.setCellSelectionEnabled(true);
        JScrollPane scrollPane = new JScrollPane(table);
        table.setDragEnabled(true);
        TableTransferHandler th = new TableTransferHandler();
        table.setTransferHandler(th);
        table.setDropTarget(new TableDropTarget(th));
        table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
        JPanel panel = new JPanel(new BorderLayout());
        panel.add(scrollPane);
        panel.setBorder(BorderFactory.createTitledBorder(tableId));
        return panel;
    public static void main(String[] args) {
        new DragDropJTableCellContents().setVisible(true);
    abstract class StringTransferHandler extends TransferHandler {
        public int dropAction;
        protected abstract String exportString(JComponent c);
        protected abstract void importString(JComponent c, String str);
        @Override
        protected Transferable createTransferable(JComponent c) {
            return new StringSelection(exportString(c));
        @Override
        public int getSourceActions(JComponent c) {
            return COPY;
        @Override
        public boolean importData(JComponent c, Transferable t) {
            if (canImport(c, t.getTransferDataFlavors())) {
                try {
                    String str = (String) t.getTransferData(DataFlavor.stringFlavor);
                    importString(c, str);
                    return true;
                } catch (UnsupportedFlavorException ufe) {
                } catch (IOException ioe) {
            return false;
        @Override
        public boolean canImport(JComponent c, DataFlavor[] flavors) {
            for (int ndx = 0; ndx < flavors.length; ndx++) {
                if (DataFlavor.stringFlavor.equals(flavors[ndx])) {
                    return true;
            return false;
    class TableTransferHandler extends StringTransferHandler {
        private int dragRow;
        private int[] dragColumns;
        private BufferedImage[] image;
        private int row;
        private int[] columns;
        public JTable target;
        @Override
        protected Transferable createTransferable(JComponent c) {
            JTable table = (JTable) c;
            dragRow = table.getSelectedRow();
            dragColumns = table.getSelectedColumns();
            createDragImage(table);
            return new StringSelection(exportString(c));
        protected String exportString(JComponent c) {
            JTable table = (JTable) c;
            row = table.getSelectedRow();
            columns = table.getSelectedColumns();
            StringBuffer buff = new StringBuffer();
            for (int j = 0; j < columns.length; j++) {
                Object val = table.getValueAt(row, columns[j]);
                buff.append(val == null ? "" : val.toString());
                if (j != columns.length - 1) {
                    buff.append(",");
            return buff.toString();
        protected void importString(JComponent c, String str) {
            target = (JTable) c;
            DefaultTableModel model = (DefaultTableModel) target.getModel();
            String[] values = str.split("\n");
            int colCount = target.getSelectedColumn();
            int max = target.getColumnCount();
            for (int ndx = 0; ndx < values.length; ndx++) {
                String[] data = values[ndx].split(",");
                for (int i = 0; i < data.length; i++) {
                    String string = data;
if(colCount < max){
model.setValueAt(string, target.getSelectedRow(), colCount);
colCount++;
public BufferedImage[] getDragImage() {
return image;
private void createDragImage(JTable table) {
if (dragColumns != null) {
try {
image = new BufferedImage[dragColumns.length];
for (int i = 0; i < dragColumns.length; i++) {
Rectangle cellBounds = table.getCellRect(dragRow, i, true);
TableCellRenderer r = table.getCellRenderer(dragRow, i);
DefaultTableModel m = (DefaultTableModel) table.getModel();
JComponent lbl = (JComponent) r.getTableCellRendererComponent(table,
table.getValueAt(dragRow, dragColumns[i]), false, false, dragRow, i);
lbl.setBounds(cellBounds);
BufferedImage img = new BufferedImage(lbl.getWidth(), lbl.getHeight(),
BufferedImage.TYPE_INT_ARGB_PRE);
Graphics2D graphics = img.createGraphics();
graphics.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 1f));
lbl.setBorder(BorderFactory.createLineBorder(Color.LIGHT_GRAY));
lbl.paint(graphics);
graphics.dispose();
image[i] = img;
} catch (RuntimeException re) {
class TableDropTarget extends DropTarget {
private Insets autoscrollInsets = new Insets(20, 20, 20, 20);
private Rectangle rect2D = new Rectangle();
private TableTransferHandler handler;
public TableDropTarget(TableTransferHandler h) {
super();
this.handler = h;
@Override
public void dragOver(DropTargetDragEvent dtde) {
handler.dropAction = dtde.getDropAction();
JTable table = (JTable) dtde.getDropTargetContext().getComponent();
Point location = dtde.getLocation();
int row = table.rowAtPoint(location);
int column = table.columnAtPoint(location);
table.changeSelection(row, column, false, false);
paintImage(table, location);
autoscroll(table, location);
super.dragOver(dtde);
public void dragExit(DropTargetDragEvent dtde) {
clearImage((JTable) dtde.getDropTargetContext().getComponent());
super.dragExit(dtde);
@Override
public void drop(DropTargetDropEvent dtde) {
Transferable data = dtde.getTransferable();
JTable table = (JTable) dtde.getDropTargetContext().getComponent();
clearImage(table);
handler.importData(table, data);
super.drop(dtde);
private final void paintImage(JTable table, Point location) {
Point pt = new Point(location);
BufferedImage[] image = handler.getDragImage();
if (image != null) {
table.paintImmediately(rect2D.getBounds());
rect2D.setLocation(pt.x - 15, pt.y - 15);
int wRect2D = 0;
int hRect2D = 0;
for (int i = 0; i < image.length; i++) {
table.getGraphics().drawImage(image[i], pt.x - 15, pt.y - 15, table);
pt.x += image[i].getWidth();
if (hRect2D < image[i].getHeight()) {
hRect2D = image[i].getHeight();
wRect2D += image[i].getWidth();
rect2D.setSize(wRect2D, hRect2D);
private final void clearImage(JTable table) {
table.paintImmediately(rect2D.getBounds());
private Insets getAutoscrollInsets() {
return autoscrollInsets;
private void autoscroll(JTable table, Point cursorLocation) {
Insets insets = getAutoscrollInsets();
Rectangle outer = table.getVisibleRect();
Rectangle inner = new Rectangle(outer.x + insets.left,
outer.y + insets.top,
outer.width - (insets.left + insets.right),
outer.height - (insets.top + insets.bottom));
if (!inner.contains(cursorLocation)) {
Rectangle scrollRect = new Rectangle(cursorLocation.x - insets.left,
cursorLocation.y - insets.top,
insets.left + insets.right,
insets.top + insets.bottom);
table.scrollRectToVisible(scrollRect);
Edited by: Andre_Uhres on Nov 18, 2007 10:03 PM