आप DefaultListSelectionModel लागू करता है करने के लिए है, तो आप फ्लैग सेट कर सकते हैं यदि IsEnabled या नहीं
सरल उदाहरण
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class JListDisabledItemDemo implements ItemListener, Runnable {
private JFrame f = new JFrame("Colors");
private static final String ITEMS[] = {" black ", " blue ", " green ",
" orange ", " purple ", " red ", " white ", " yellow "};
private JList jList;
private JCheckBox[] checkBoxes;
private boolean[] enabledFlags;
@Override
public void run() {
JPanel pnlEnablers = new JPanel(new GridLayout(0, 1));
pnlEnablers.setBorder(BorderFactory.createTitledBorder("Enabled Items"));
checkBoxes = new JCheckBox[ITEMS.length];
enabledFlags = new boolean[ITEMS.length];
for (int i = 0; i < ITEMS.length; i++) {
checkBoxes[i] = new JCheckBox(ITEMS[i]);
checkBoxes[i].setSelected(true);
checkBoxes[i].addItemListener(this);
enabledFlags[i] = true;
pnlEnablers.add(checkBoxes[i]);
}
jList = new JList(ITEMS);
jList.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
jList.setSelectionModel(new DisabledItemSelectionModel());
jList.setCellRenderer(new DisabledItemListCellRenderer());
jList.addListSelectionListener(new ListSelectionListener() {
@Override
public void valueChanged(ListSelectionEvent e) {
if (!e.getValueIsAdjusting()) {
System.out.println("selection");
}
}
});
JScrollPane scroll = new JScrollPane(jList);
scroll.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
scroll.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
Container contentPane = f.getContentPane();
contentPane.setLayout(new GridLayout(1, 2));
contentPane.add(pnlEnablers);
contentPane.add(scroll);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLocation(240, 280);
UIManager.put("List.background", Color.lightGray);
UIManager.put("List.selectionBackground", Color.orange);
UIManager.put("List.selectionForeground", Color.blue);
UIManager.put("Label.disabledForeground", Color.magenta);
SwingUtilities.updateComponentTreeUI(f);
f.pack();
javax.swing.SwingUtilities.invokeLater(new Runnable() {
@Override
public void run() {
f.setVisible(true);
}
});
}
@Override
public void itemStateChanged(ItemEvent event) {
JCheckBox checkBox = (JCheckBox) event.getSource();
int index = -1;
for (int i = 0; i < ITEMS.length; i++) {
if (ITEMS[i].equals(checkBox.getText())) {
index = i;
break;
}
}
if (index != -1) {
enabledFlags[index] = checkBox.isSelected();
jList.repaint();
}
}
public static void main(String args[]) {
SwingUtilities.invokeLater(new JListDisabledItemDemo());
}
private class DisabledItemListCellRenderer extends DefaultListCellRenderer {
private static final long serialVersionUID = 1L;
@Override
public Component getListCellRendererComponent(JList list, Object value, int index, boolean isSelected, boolean cellHasFocus) {
Component comp = super.getListCellRendererComponent(list, value, index, false, false);
JComponent jc = (JComponent) comp;
if (enabledFlags[index]) {
if (isSelected & cellHasFocus) {
comp.setForeground(Color.black);
comp.setBackground(Color.red);
} else {
comp.setForeground(Color.blue);
}
if (!isSelected) {
if ((value.toString()).trim().equals("yellow")) {
comp.setForeground(Color.orange);
comp.setBackground(Color.magenta);
}
}
return comp;
}
comp.setEnabled(false);
return comp;
}
}
private class DisabledItemSelectionModel extends DefaultListSelectionModel {
private static final long serialVersionUID = 1L;
@Override
public void setSelectionInterval(int index0, int index1) {
if (enabledFlags[index0]) {
super.setSelectionInterval(index0, index0);
} else {
/*
* The previously selected index is before this one,
* so walk forward to find the next selectable item.
*/
if (getAnchorSelectionIndex() < index0) {
for (int i = index0; i < enabledFlags.length; i++) {
if (enabledFlags[i]) {
super.setSelectionInterval(i, i);
return;
}
}
} /*
* Otherwise, walk backward to find the next selectable item.
*/ else {
for (int i = index0; i >= 0; i--) {
if (enabledFlags[i]) {
super.setSelectionInterval(i, i);
return;
}
}
}
}
}
}
}
चरण "सक्षम" करने के लिए कौन सी कार्रवाइयां आवश्यक हैं, यह एक अच्छा जवाब है जब आप अक्षम दिखाना चाहते हैं आइटम नहीं है। कुछ उपयोग मामले हैं जहां वास्तव में ऐसा करना बेहतर होता है। मेरे पास ऐसा उपयोग मामला है और यह एक आकर्षण की तरह काम करता है। –