Author: Zafir Anjum

Display any JComponent in a cell. Sample shows buttons, labels, combobox, scrolbar and radio buttons. These components behave in the regular manner to mouse actions.

The sample below shows how to implement this. To achieve this we need three classes.

JTable has been anonymously subclassed below but you may wish to create a public class with this feature. This subclass of JTable overrides only two methods - getCellRenderer() and getCellEditor(). These methods make sure that the right object is returned. Note that we also set the default cell renderer and cell editor for the JComponent class. With this mechanism, you could at a later time create a custom renderer (or editor) for any of the swing components and simply call setDefaultRenderer() for this custom renderer to get used.

The JComponentCellRenderer implements the TableCellRenderer and its single method simply returns the component in the cell to be rendered.

The JComponentCellEditor is also mostly simple. The handler of the event listener list is borrowed from one of the swing classes. This class essentially uses the component in the cell as the editor too. The only mysterious code is in shouldSelectCell(). What it does is create a dummy mouse_release and mouse_clicked events on the component. The reason for this is that the TableUI class passes on the event that initiated the edit ( the mouse_pressed event ) to the editor component. Since many components expect mouse_released and mouse_clicked to follow, we oblige these components.

// File: Table.java
// Author: Zafir Anjum
import java.awt.*;
import java.util.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.table.*;

public class Table
{
	public static void main(String[] args)
	{
		JFrame frame = new JFrame("Table");
		frame.addWindowListener( new WindowAdapter() {
			public void windowClosing(WindowEvent e)
			{
				Window win = e.getWindow();
				win.setVisible(false);
				win.dispose();
				System.exit(0);
			}
		} );
		
		JTable table = new JTable( 6,4 )
		{
			public TableCellRenderer getCellRenderer(int row, int column) {
				TableColumn tableColumn = getColumnModel().getColumn(column);
				TableCellRenderer renderer = tableColumn.getCellRenderer();
				if (renderer == null) {
					Class c = getColumnClass(column);
					if( c.equals(Object.class) )
					{
						Object o = getValueAt(row,column);
						if( o != null )
							c = getValueAt(row,column).getClass();
					}
					renderer = getDefaultRenderer(c);
				}
				return renderer;
			}
			
			public TableCellEditor getCellEditor(int row, int column) {
				TableColumn tableColumn = getColumnModel().getColumn(column);
				TableCellEditor editor = tableColumn.getCellEditor();
				if (editor == null) {
					Class c = getColumnClass(column);
					if( c.equals(Object.class) )
					{
						Object o = getValueAt(row,column);
						if( o != null )
							c = getValueAt(row,column).getClass();
					}
					editor = getDefaultEditor(c);
				}
				return editor;
			}
			
		};
		
		// Buttons
		table.setValueAt( new JButton("Button"), 0, 0 );
		table.setValueAt( new JButton("Button"), 0, 1 );
		
		
		// Combobox
		JComboBox combo = new JComboBox( new String[] {"First", "Second", "Third"} );
		table.setValueAt( combo, 1, 1 );
		
		// Labels
		table.setValueAt( new JLabel("Label"), 1, 0 );
		JLabel label = new JLabel( "Label", new ImageIcon( table.getClass().getResource("new.gif") ),
			JLabel.LEFT);
		table.setValueAt( label, 1, 2 );
		
		// Scrollbar
		table.setValueAt( new JScrollBar(JScrollBar.HORIZONTAL), 2,1 );
		
		// RadioButtons
		JRadioButton b1 = new JRadioButton( "Group1 Button1" );
		JRadioButton b2 = new JRadioButton( "Group1 Button2" );
		JRadioButton b3 = new JRadioButton( "Group1 Button3" );
		
		ButtonGroup g1 = new ButtonGroup();
		g1.add( b1 );
		g1.add( b2 );
		g1.add( b3 );
		
		table.setValueAt( b1, 3, 0 );
		table.setValueAt( b2, 3, 1 );
		table.setValueAt( b3, 3, 2 );
		
		table.setDefaultRenderer( JComponent.class, new JComponentCellRenderer() );
		table.setDefaultEditor( JComponent.class, new JComponentCellEditor() );
		JScrollPane sp = new JScrollPane(table);
		
		
		frame.getContentPane().add( sp );
		frame.pack();
		frame.show();
	}
}


class JComponentCellRenderer implements TableCellRenderer
{
    public Component getTableCellRendererComponent(JTable table, Object value,
		boolean isSelected, boolean hasFocus, int row, int column) {
        return (JComponent)value;
    }
}





// File: JComponentCellEditor.java
// Author: Zafir Anjum
import java.awt.Component;
import java.awt.event.*;
import java.awt.AWTEvent;
import java.lang.Boolean;
import javax.swing.table.*;
import javax.swing.event.*;
import java.util.EventObject;
import javax.swing.tree.*;
import java.io.Serializable;
import javax.swing.*;


public class JComponentCellEditor implements TableCellEditor, TreeCellEditor,
Serializable {
	
	protected EventListenerList listenerList = new EventListenerList();
	transient protected ChangeEvent changeEvent = null;
	
	protected JComponent editorComponent = null;
	protected JComponent container = null;		// Can be tree or table
	
	
	public Component getComponent() {
		return editorComponent;
	}
	
	
	public Object getCellEditorValue() {
		return editorComponent;
	}
	
	public boolean isCellEditable(EventObject anEvent) {
		return true;
	}
	
	public boolean shouldSelectCell(EventObject anEvent) {
		if( editorComponent != null && anEvent instanceof MouseEvent
			&& ((MouseEvent)anEvent).getID() == MouseEvent.MOUSE_PRESSED )
		{
            Component dispatchComponent = SwingUtilities.getDeepestComponentAt(editorComponent, 3, 3 );
			MouseEvent e = (MouseEvent)anEvent;
			MouseEvent e2 = new MouseEvent( dispatchComponent, MouseEvent.MOUSE_RELEASED,
				e.getWhen() + 100000, e.getModifiers(), 3, 3, e.getClickCount(),
				e.isPopupTrigger() );
			dispatchComponent.dispatchEvent(e2); 
			e2 = new MouseEvent( dispatchComponent, MouseEvent.MOUSE_CLICKED,
				e.getWhen() + 100001, e.getModifiers(), 3, 3, 1,
				e.isPopupTrigger() );
			dispatchComponent.dispatchEvent(e2); 
		}
		return false;
	}
	
	public boolean stopCellEditing() {
		fireEditingStopped();
		return true;
	}
	
	public void cancelCellEditing() {
		fireEditingCanceled();
	}
	
	public void addCellEditorListener(CellEditorListener l) {
		listenerList.add(CellEditorListener.class, l);
	}
	
	public void removeCellEditorListener(CellEditorListener l) {
		listenerList.remove(CellEditorListener.class, l);
	}
	
	protected void fireEditingStopped() {
		Object[] listeners = listenerList.getListenerList();
		// Process the listeners last to first, notifying
		// those that are interested in this event
		for (int i = listeners.length-2; i>=0; i-=2) {
			if (listeners[i]==CellEditorListener.class) {
				// Lazily create the event:
				if (changeEvent == null)
					changeEvent = new ChangeEvent(this);
				((CellEditorListener)listeners[i+1]).editingStopped(changeEvent);
			}	       
		}
	}
	
	protected void fireEditingCanceled() {
		// Guaranteed to return a non-null array
		Object[] listeners = listenerList.getListenerList();
		// Process the listeners last to first, notifying
		// those that are interested in this event
		for (int i = listeners.length-2; i>=0; i-=2) {
			if (listeners[i]==CellEditorListener.class) {
				// Lazily create the event:
				if (changeEvent == null)
					changeEvent = new ChangeEvent(this);
				((CellEditorListener)listeners[i+1]).editingCanceled(changeEvent);
			}	       
		}
	}
	
	// implements javax.swing.tree.TreeCellEditor
	public Component getTreeCellEditorComponent(JTree tree, Object value,
		boolean isSelected, boolean expanded, boolean leaf, int row) {
		String         stringValue = tree.convertValueToText(value, isSelected,
			expanded, leaf, row, false);
		
		editorComponent = (JComponent)value;
		container = tree;
		return editorComponent;
	}
	
	// implements javax.swing.table.TableCellEditor
	public Component getTableCellEditorComponent(JTable table, Object value,
		boolean isSelected, int row, int column) {
		
		editorComponent = (JComponent)value;
		container = table;
		return editorComponent;
	}
	
} // End of class JComponentCellEditor

Posted On: 7-Jan-1999

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