Jtable mouse header cursor

[Sabine El Rassy]

Hello,

when the mouse cursor is over the boundary between the headers of two adjacent columns in a jtable, it changes to a double headed arrow, indicating that the column width can be changed by dragging the mouse. How can I put a listener that tells me when the mouse icon has changed from a simpe mouse pointer to a double headed arrow <-> ?
Thanks

[Darryl Burke]

This begs the question: how do you intend to use that information? I ask because I believe there may be (probably is) a better way of achieving that than this approach.

And welcome to the Ranch!

[Sabine El Rassy]

thanks
I need to do like excel, when the user double click on the header while its double headed arrow, the column width will take its max value.
I have done this , but Im just wondering If there's some other way?

	int currentColumnIndexModified = Table.getTableHeader().getColumnModel().getColumnIndexAtX(e.getX()-3);
					Double headerNextBorne = new Double(Table.getTableHeader().getHeaderRect(currentColumnIndexModified).getMaxX()+3 +Table.getLocationOnScreen().getX());
					PointerInfo pointer = MouseInfo.getPointerInfo();
					if (pointer.getLocation().x-5>Table.getLocationOnScreen().x && 
							pointer.getLocation().x<headerNextBorne && 	headerNextBorne-pointer.getLocation().x<8) {
					Table.getColumnModel().getColumn(currentColumnIndexModified).setPreferredWidth(maxWidth);

					}

[Rob Camick]

How can I put a listener that tells me when the mouse icon has changed from a simpe mouse pointer to a double headed arrow

I don't think there is an event for this, but you can check to see which cursor is displayed when the mouse click event is generated.

Here is my solution that uses this approach. To resize the row you use a double click. Note, the code appears more complicated because it will also handle the situation where a sorter is being used on the table. That is, when you click in the resizing area, sorting on the row will NOT be invoked.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;

public class ResizeColumnListener implements MouseListener
{
    private static Cursor resizeCursor = Cursor.getPredefinedCursor(Cursor.E_RESIZE_CURSOR);

	private MouseListener uiListener;
	private JTableHeader header;
	private TableColumnAdjuster tca;

	public ResizeColumnListener(JTable table)
	{
		header = table.getTableHeader();
		tca = new TableColumnAdjuster( table );

		MouseListener[] listeners = header.getMouseListeners();

		for (MouseListener ml: listeners)
		{
			String className = ml.getClass().toString();

			if (className.contains("BasicTableHeaderUI"))
			{
				uiListener = ml;
				header.removeMouseListener(ml);
				header.addMouseListener( this );
			}
		}
	}

	@Override
	public void mouseClicked( MouseEvent e )
	{
		if (header.getCursor() != resizeCursor)
		{
			uiListener.mouseClicked( e );
			return;
		}

		//  Handle the double click event to resize the column
		//  Note: The last 3 pixels + 3 pixels of next column are for resizing,
		//  so we need to adjust the mouse point to get the actual column.

		if (e.getClickCount() == 2)
		{
			Point p = e.getPoint();
			p.x -= 3;
			int column = header.columnAtPoint( p );
			tca.adjustColumn( column );

			//  Generate event to reset the cursor

			header.dispatchEvent(new MouseEvent(
				header,
				MouseEvent.MOUSE_MOVED,
				e.getWhen(),
				e.getModifiers(),
				e.getX(),
				e.getY(),
				0,
				false));
		}
	}

	@Override
	public void mouseEntered( MouseEvent e )
	{
		uiListener.mouseEntered( e );
	}

	@Override
	public void mouseExited( MouseEvent e )
	{
		uiListener.mouseExited( e );
	}

	@Override
	public void mousePressed( MouseEvent e )
	{
		uiListener.mousePressed( e );
	}

	@Override
	public void mouseReleased( MouseEvent e )
	{
		uiListener.mouseReleased( e );
	}

	public static void main(String[] args)
	{
		try
		{
//			UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
		}
		catch (Exception e) { }

		DefaultTableModel model = new DefaultTableModel(5, 5);
		model.setValueAt("Row 0 : Column 0", 0, 0);
		model.setValueAt("Row 1 : Column 1", 1, 1);
		model.setValueAt("Row 2 : Column 2", 2, 2);
		model.setValueAt("Row 3 : Column 3", 3, 3);
		model.setValueAt("Row 4 : Column 4", 4, 4);

		JTable table = new JTable( model );
		table.setAutoResizeMode(JTable.AUTO_RESIZE_OFF);
		table.setAutoCreateRowSorter(true);
		JScrollPane scrollPane = new JScrollPane( table );

    	new ResizeColumnListener(table);

		JFrame frame = new JFrame();
		frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
		frame.add( scrollPane );
		frame.setSize(400, 200);
		frame.setVisible(true);
	}
}

Note: the above code uses the Table Column Adjuster class to determine the maximum width of the column.

[Darryl Burke]

I would recommend a MouseListener added to the table header with its mouseClicked(...) code something like

        if (e.getClickCount() < 2) {
          return;
        }
        int px = e.getPoint().x;
        int x = 0;
        for (int i = 0; i < table.getColumnCount(); i++) {
          if (Math.abs(px - x) <= 3) {
            System.out.println("Column to resize: " + (i - 1));
            // do stuff with column(i - 1)
          }
          x += table.getColumnModel().getColumn(i).getWidth();
        }

For your original approach, you could extend JTableHeader and override getCursor() to call firePropertyChanged("cursor") whenever the cursor changes

      Cursor lastCursor;

      @Override
      public Cursor getCursor() {
        Cursor currentCursor = super.getCursor();
        if (currentCursor != lastCursor) {
          firePropertyChange("CURSOR", lastCursor, currentCursor);
          lastCursor = currentCursor;
        }
        return currentCursor;
      }

And listen for the property change

addPropertyChangeListener("CURSOR", new PropertyChangeListener() {

      @Override
      public void propertyChange(PropertyChangeEvent evt) {
        System.out.println(evt.getNewValue());
      }
    });

I wouldn't recommend this as it involves extending a core class -- which is avoidable by adopting the MouseListener approach.
edit: and requires still more code to determine which column to resize.

[Sabine El Rassy]

I tried both methods and it works! thanks =)