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Need to display a JSeparator in a JComboBox

Posted on 2008-10-02
5
879 Views
Last Modified: 2013-12-17
I use the following comboBox to display a set of strings to the operator, that will
grey out the third selection (see "Text Line 3", false)...
My problem is that the separator does not display correctly - it seems to produce the ToString()
results in the line of text. What can I do to display the horizontal separator in the comboBox list?

Thanks

Object[] items = { 	new ComboItem<String>(new String("Text Line 1"), true),

					new ComboItem<String>(new String("Text Line 2"), true), 

					new ComboItem<JSeparator>(new JSeparator(), true),

					new ComboItem<String>(new String("Text Line 3"), false), 

				

				

		selectionComboBox = new JComboBox(items);

		selectionComboBox.setRenderer(new ComboRenderer());

		selectionComboBox.addActionListener(new ComboListener(selectionComboBox));

		selectionComboBox.setBounds(140, 101, 254, 25);

		selectionComboBox.setMaximumRowCount(14);

		getContentPane().add(selectionComboBox);

		

		// CellRenderer

		class ComboRenderer extends JLabel implements ListCellRenderer {

		private static final long serialVersionUID = 1L;
 

		public ComboRenderer() {

			setOpaque(true);

			setBorder(new EmptyBorder(1, 1, 1, 1));

		}
 

		public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected,

				boolean cellHasFocus) {

			if (isSelected) {

				setBackground(list.getSelectionBackground());

				setForeground(list.getSelectionForeground());

			} else {

				setBackground(list.getBackground());

				setForeground(list.getForeground());

			}

			if (!((CanEnable) value).isEnabled()) {

				setBackground(list.getBackground());

				setForeground(UIManager.getColor("Label.disabledForeground"));

			}

			setFont(list.getFont());

			setText((value == null) ? "" : value.toString());

			return this;

		}

	}
 

	/**

	 * Handles the combo box selection

	 *

	 */

	class ComboListener implements ActionListener {

		JComboBox combo;

		Object currentItem;
 

		ComboListener(JComboBox combo) {

			this.combo = combo;

			combo.setSelectedIndex(0);

			currentItem = combo.getSelectedItem();

		}
 

		public void actionPerformed(ActionEvent e) {

			Object tempItem = combo.getSelectedItem();

			if (!((CanEnable) tempItem).isEnabled()) {

				combo.setSelectedItem(currentItem);

			} else {

				currentItem = tempItem;

			}

		}

	}
 

	/**

	 * The item displayed by the combo box

	 *

	 * @param <T>

	 */

	class ComboItem<T> implements CanEnable {

		T obj;

		boolean isEnable;
 

		ComboItem(T obj, boolean isEnable) {

			this.obj = obj;

			this.isEnable = isEnable;

		}
 

		ComboItem(T obj) {

			this(obj, true);

		}
 

		public boolean isEnabled() {

			return isEnable;

		}
 

		public void setEnabled(boolean isEnable) {

			this.isEnable = isEnable;

		}
 

		public String toString() {

			return obj.toString();

		}
 

		public T getValue() {

			return obj;

		}

	}

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Question by:dbCnc
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5 Comments
 
LVL 37

Expert Comment

by:zzynx
ID: 22633653
>> My problem is that the separator does not display correctly - it seems to produce the ToString()

Sure. That's what you told it to do:

setText((value == null) ? "" : value.toString());
0
 

Author Comment

by:dbCnc
ID: 22635643
xxynk,

Thanks for the reply - but it's still not obvious to me how to display the separator as a line.

==>Sure. That's what you told it to do:
==>setText((value == null) ? "" : value.toString());

Perhaps I can test the obj T in ComboItem, and do something different from what is returned in line 93,
but I want a solid line to appear - of the correct length for the displayed ComboBox.

Could you elaborate?

Thanks again...
0
 
LVL 37

Accepted Solution

by:
zzynx earned 500 total points
ID: 22677209
0
 

Author Closing Comment

by:dbCnc
ID: 31504684
ZZYNX,

The first solution was exactly what I was looking for. I had gone through quite a few examples from that site - but never found that one.

I added my enable/disable code to the listeners, and I'm all set...

Thanks Again
0
 
LVL 37

Expert Comment

by:zzynx
ID: 22679280
Thanx 4 axxepting
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