selecting column names dynamically from table column header

[neha_sinha]

hello,

could anyone please help me out as how to select column names dynamically from the table column header.the table column header has fewer columns displayed than what declared in the table column model.

regards,
neha

[camickr]

Table Column Manager allows the user to right click on the table header to control which columns are visible.

import java.awt.*;
import java.util.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;
 
public class TableColumnManager implements MouseListener, ActionListener
{
	//
	private static final String HIDDEN_COLUMN = "HiddenColumn:";
 
	//  Reference to the Singleton instance of this class
	private static TableColumnManager singleton;
 
    /**
     *  Use a private constructor so we can create a Singleton.
     */
	private TableColumnManager()
	{
	}
 
    /**
     *  Get the Singleton instance of the TableColumnManager.
     *
     *  @return  the Singlton instance of TableColumnManager
     */
	private static TableColumnManager getInstance()
	{
		if (singleton == null)
		{
			singleton = new TableColumnManager();
		}
 
		return singleton;
	}
 
    /**
     *  Add support for the management of visible TableColumns
     *  for a given JTable.
     *
     *  @param  table the table to provide support for
     */
	public static void install(JTable table)
	{
		table.getTableHeader().addMouseListener( getInstance() );
	}
 
    /**
     *  Remove support for the management of visible TableColumns
     *  for a given JTable.
     *
     *  @param  table the table to remove support from
     */
	public static void uninstall(JTable table)
	{
		table.getTableHeader().removeMouseListener( getInstance() );
	}
 
    /**
     *  Hide a column from view in the table.
     *
     *  @param  table        the table from which the column is removed
     *  @param  modelColumn  the column index from the TableModel
     *                       of the column to be removed
     */
	public static void hideColumn(JTable table, int modelColumn)
	{
		int viewColumn = table.convertColumnIndexToView( modelColumn );
 
		if (viewColumn != -1)
		{
			TableColumn column = table.getColumnModel().getColumn(viewColumn);
			hideColumn(table, column);
		}
	}
 
    /**
     *  Hide a column from view in the table.
     *
     *  @param  table        the table from which the column is removed
     *  @param  columnName   the column name of the column to be removed
     */
	public static void hideColumn(JTable table, String columnName)
	{
		try
		{
			TableColumnModel tcm = table.getColumnModel();
			int index = tcm.getColumnIndex( columnName );
			TableColumn column = tcm.getColumn( index );
			hideColumn(table, column);
		}
		catch(IllegalArgumentException e) {}
	}
 
    /**
     *  Hide a column from view in the table.
     *
     *  @param  table   the table from which the column is removed
     *  @param  column  the TableColumn to be removed from the
     *                  TableColumnModel of the specified table
     */
	public static void hideColumn(JTable table, TableColumn column)
	{
		table.getColumnModel().removeColumn( column );
 
		//  Save the column so it can be redisplayed
 
		ArrayList list = (ArrayList)table.getClientProperty(HIDDEN_COLUMN);

		if (list == null)
		{
			list = new ArrayList();
			table.putClientProperty(HIDDEN_COLUMN, list);
		}

		list.add(column);
	}

    /**
     *  Show a hidden column in the table.
     *
     *  @param  table        the table to which the column is added
     *  @param  modelColumn  the column index from the TableModel
     *                       of the column to be added
     */
	public static void showColumn(JTable table, int modelColumn)
	{
		ArrayList list = (ArrayList)table.getClientProperty(HIDDEN_COLUMN);

		if (list == null) return;

		ListIterator it = list.listIterator();

		while (it.hasNext())
		{
			TableColumn column = (TableColumn)it.next();

			if (column.getModelIndex() == modelColumn)
			{
				table.getColumnModel().addColumn( column );
				it.remove();
				break;
			}
		}
	}

    /**
     *  Show a hidden column in the table.
     *
     *  @param  table        the table to which the column is added
     *  @param  columnName   the column name from the TableModel
     *                       of the column to be added
     */
	public static void showColumn(JTable table, String columnName)
	{
		ArrayList list = (ArrayList)table.getClientProperty(HIDDEN_COLUMN);

		if (list == null) return;

		ListIterator it = list.listIterator();

		while (it.hasNext())
		{
			TableColumn column = (TableColumn)it.next();

			if (column.getHeaderValue().equals(columnName))
			{
				table.getColumnModel().addColumn( column );
				it.remove();
				break;
			}
		}
	}

	//  Implement the MouseListener

	public void mousePressed(MouseEvent e)
	{
		checkForPopup( e );
	}
 
	public void mouseReleased(MouseEvent e)
	{
		checkForPopup( e );
	}
 
	public void mouseClicked(MouseEvent e) {}
	public void mouseEntered(MouseEvent e) {}
	public void mouseExited(MouseEvent e) {}
 
	private void checkForPopup(MouseEvent e)
	{
		if (e.isPopupTrigger())
		{
			JTableHeader header = (JTableHeader)e.getComponent();
			int column = header.columnAtPoint( e.getPoint() );
			showPopup(header.getTable(), column);
		}
	}
 
    /**
     *  Show a hidden column in the table.
     *
     *  @param  table        the table to which the column is added
     *  @param  columnName   the column name from the TableModel
     *                       of the column to be added
     */
	public static void showPopup(JTable table, int tableColumn)
	{
		int columns = table.getModel().getColumnCount();
		JCheckBoxMenuItem[] items = new JCheckBoxMenuItem[columns];
 
		//  Create menu items for hidden columns
 
   		ArrayList list = (ArrayList)table.getClientProperty(HIDDEN_COLUMN);
 
   		if (list != null)
   		{
			ListIterator it = list.listIterator();
 
			while (it.hasNext())
			{
				TableColumn column = (TableColumn)it.next();
				String columnName = column.getHeaderValue().toString();
				JCheckBoxMenuItem item = new JCheckBoxMenuItem( columnName );
				item.setSelected( false );
				item.addActionListener(getInstance());
				items[column.getModelIndex()] = item;
			}
   		}
 
		//  Create menu items for visible columns

		TableColumnModel columnModel = table.getColumnModel();
		int columnCount = columnModel.getColumnCount();

		for (int i = 0; i < columnCount; i++)
		{
			TableColumn column = columnModel.getColumn(i);
			String columnName = column.getHeaderValue().toString();
			JCheckBoxMenuItem item = new JCheckBoxMenuItem( columnName );
			item.setSelected( true );
			item.addActionListener(getInstance());

			if (columnCount == 1)
				item.setEnabled( false );

			items[column.getModelIndex()] = item;
		}


		//  Create popup menu from array of menu items.
		//  Override method to select the specified menu item.
		//  (ie. this is a bug? fix)

		JPopupMenu popup = new JPopupMenu()
		{
			public void setSelected(Component sel)
			{
				int index = getComponentIndex( sel );
				getSelectionModel().setSelectedIndex(index);
				final MenuElement me[] = new MenuElement[2];
				me[0]=(MenuElement)this;
				me[1]=getSubElements()[index];

				SwingUtilities.invokeLater(new Runnable()
				{
					public void run()
					{
						MenuSelectionManager.defaultManager()
							.setSelectedPath(me);
					}
				});
			}
		};

		for (int i = 0; i < items.length; i++)
		{
			if (items[i] != null)
			{
				popup.add( items[i] );
			}
		}

		//  Display the popup below the TableHeader

		JTableHeader header = table.getTableHeader();
		Rectangle r = header.getHeaderRect( tableColumn );
		popup.show(header, r.x, r.height);
		int modelColumn = table.convertColumnIndexToModel( tableColumn );
		popup.setSelected( items[modelColumn] );
	}

    /**
     *  Responsible for processing the ActionEvent. A column will either be
     *  added to the table or removed from the table depending on the state
     *  of the menu item that was clicked.
     *
     * @param event the ActionEvent.
     */
	public void actionPerformed(ActionEvent event)
    {
		JMenuItem item = (JMenuItem)event.getSource();
		JPopupMenu popup = (JPopupMenu)item.getParent();
		JTableHeader header = (JTableHeader)popup.getInvoker();
		JTable table = header.getTable();

		if (item.isSelected())
		{
			showColumn(table, item.getText());
		}
		else
		{
			hideColumn(table, item.getText());
		}
	}

	public static void main(String[] args)
	{
		JTable table = new JTable( new DefaultTableModel(5, 10) );

		TableColumnManager.install(table);
		TableColumnManager.hideColumn(table, 2);
		TableColumnManager.hideColumn(table, "E");
 
		JFrame frame = new JFrame();
		frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
		frame.getContentPane().add( new JScrollPane(table) );
		frame.pack();
		frame.setVisible( true );
	 }
}