Disabled ComboBox Example
// Example from http://www.crionics.com/products/opensource/faq/swing_ex/SwingExamples.html
/* (swing1.1) */
import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JList;
import javax.swing.ListCellRenderer;
import javax.swing.UIManager;
import javax.swing.border.EmptyBorder;
/**
* @version 1.0 12/26/98
*/
public class DisabledComboBoxExample extends JFrame {
public DisabledComboBoxExample() {
super("Disabled Item ComboBox Example");
Object[] items = { new ComboItem("A"), new ComboItem("B"),
new ComboItem("1", false), new ComboItem("2", false),
new ComboItem("abc"), new ComboItem("def") };
JComboBox combo = new JComboBox(items);
combo.setRenderer(new ComboRenderer());
combo.addActionListener(new ComboListener(combo));
getContentPane().setLayout(new FlowLayout());
getContentPane().add(combo);
setSize(300, 100);
setVisible(true);
}
public static void main(String args[]) {
try {
UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");
} catch (Exception evt) {}
DisabledComboBoxExample frame = new DisabledComboBoxExample();
frame.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
}
class ComboRenderer extends JLabel implements ListCellRenderer {
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;
}
}
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;
}
}
}
class ComboItem implements CanEnable {
Object obj;
boolean isEnable;
ComboItem(Object obj, boolean isEnable) {
this.obj = obj;
this.isEnable = isEnable;
}
ComboItem(Object obj) {
this(obj, true);
}
public boolean isEnabled() {
return isEnable;
}
public void setEnabled(boolean isEnable) {
this.isEnable = isEnable;
}
public String toString() {
return obj.toString();
}
}
}
interface CanEnable {
public void setEnabled(boolean isEnable);
public boolean isEnabled();
}
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