Java Tutorial/Swing/JList Selection

Add another selection - the third item

   <source lang="java">

import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   int start = 2;
   int end = 2;
   list.addSelectionInterval(start, end); 
 }

}</source>

A single-selection JList.

   <source lang="java">

import java.awt.FlowLayout; import javax.swing.JFrame; import javax.swing.JList; import javax.swing.JScrollPane; import javax.swing.ListSelectionModel; import javax.swing.event.ListSelectionEvent; import javax.swing.event.ListSelectionListener; public class Main {

 String languages[] = { "Java", "Perl", "Python", "C++", "Basic", "C#" };
 JList jlst = new JList(languages);
 Main() {
   JFrame jfrm = new JFrame("Use JList");
   jfrm.setLayout(new FlowLayout());
   jfrm.setSize(200, 160);
   jfrm.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
   jlst.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
   jlst.addListSelectionListener(new ListSelectionListener() {
     public void valueChanged(ListSelectionEvent le) {
       int idx = jlst.getSelectedIndex();
       if (idx != -1)
         System.out.println("Current selection: " + languages[idx]);
       else
         System.out.println("Please choose a language.");
     }
   });
   jfrm.add(new JScrollPane(jlst));
   jfrm.setSize(300, 300);
   jfrm.setVisible(true);
 }
 public static void main(String args[]) {
   new Main();
 }

}</source>

Clear all selections

   <source lang="java">

import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   list.clearSelection();
 }

}</source>

Deselect the first item

   <source lang="java">

import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   int start = 0;
   int end = 0;
   list.removeSelectionInterval(start, end);
 }

}</source>

Determine if there are any selected items

   <source lang="java">

import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   boolean anySelected = !list.isSelectionEmpty();
 }

}</source>

Get the index of the last selected item

   <source lang="java">

import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   int lastSelIx = list.getMaxSelectionIndex();
 }

}</source>

Getting the Selected Items in a JList Component

   <source lang="java">

import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   // Get the index of all the selected items
   int[] selectedIx = list.getSelectedIndices();
   // Get all the selected items using the indices
   for (int i = 0; i < selectedIx.length; i++) {
     Object sel = list.getModel().getElementAt(selectedIx[i]);
   }
   // Get the index of the first selected item
   int firstSelIx = list.getSelectedIndex();
 }

}</source>

Listening for Changes to the Items in a JList Component

   <source lang="java">

import javax.swing.DefaultListModel; import javax.swing.JList; import javax.swing.event.ListDataEvent; import javax.swing.event.ListDataListener; public class Main {

 public static void main(String[] argv) throws Exception {
   JList list = new JList();
   // Register a list data listener
   DefaultListModel model = (DefaultListModel) list.getModel();
   model.addListDataListener(new MyListDataListener());
 }

} class MyListDataListener implements ListDataListener {

 public void intervalAdded(ListDataEvent evt) {
   DefaultListModel model = (DefaultListModel) evt.getSource();
   int start = evt.getIndex0();
   int end = evt.getIndex1();
   int count = end - start + 1;
   for (int i = start; i <= end; i++) {
     Object item = model.getElementAt(i);
   }
 }
 public void intervalRemoved(ListDataEvent evt) {
   int start = evt.getIndex0();
   int end = evt.getIndex1();
   int count = end - start + 1;
 }
 public void contentsChanged(ListDataEvent evt) {
   DefaultListModel model = (DefaultListModel) evt.getSource();
   int start = evt.getIndex0();
   int end = evt.getIndex1();
   int count = end - start + 1;
   for (int i = start; i <= end; i++) {
     Object item = model.getElementAt(i);
   }
 }

}</source>

Listening for Changes to the Selection in a JList Component

   <source lang="java">

import javax.swing.JList; import javax.swing.event.ListSelectionEvent; import javax.swing.event.ListSelectionListener; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   list.addListSelectionListener(new MyListSelectionListener());
 }

} class MyListSelectionListener implements ListSelectionListener {

 public void valueChanged(ListSelectionEvent evt) {
   if (!evt.getValueIsAdjusting()) {
     JList list = (JList) evt.getSource();
     Object[] selected = list.getSelectedValues();
     for (int i = 0; i < selected.length; i++) {
       Object sel = selected[i];
     }
   }
 }

}</source>

List selection event

   <source lang="java">

import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.util.Vector; import javax.swing.JComboBox; import javax.swing.JLabel; import javax.swing.JList; import javax.swing.ListModel; import javax.swing.event.ListSelectionEvent; import javax.swing.event.ListSelectionListener; public class SelectionHandler implements ActionListener, ListSelectionListener {

 private JLabel direction;
 private JList source, destination;
 public SelectionHandler(JLabel d, JList left, JList right) {
   direction = d;
   source = left;
   destination = right;
 }
 public void actionPerformed(ActionEvent a) {
   JComboBox cb = (JComboBox) a.getSource();
   String selected = (String) cb.getSelectedItem();
   String current = direction.getText();
   if (!selected.equals(current)) {
     direction.setText(selected);
     JList temp = source;
     source = destination;
     destination = temp;
     source.clearSelection();
     destination.clearSelection();
   }
 }
 public void valueChanged(ListSelectionEvent e) {
   JList list = (JList) e.getSource();
   String item = (String) source.getSelectedValue();
   System.out.println(item);
   if (item != null && !item.equals("")) {
     removeFromSource(item);
     addToDestination(item);
   }
 }
 private void removeFromSource(String item) {
   ListModel model = source.getModel();
   Vector listData = new Vector();
   for (int i = 0; i < model.getSize(); i++) {
     listData.addElement(model.getElementAt(i));
   }
   listData.removeElement(item);
   source.setListData(listData);
 }
 private void addToDestination(String item) {
   ListModel model = destination.getModel();
   Vector listData = new Vector();
   for (int i = 0; i < model.getSize(); i++) {
     listData.addElement(model.getElementAt(i));
   }
   listData.addElement(item);
   destination.setListData(listData);
 }

}</source>

Multiple ranges of selected items are allowed

   <source lang="java">

import javax.swing.DefaultListSelectionModel; import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   list.setSelectionMode(DefaultListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
 }

}</source>

Select all the items

   <source lang="java">

import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   int start = 0;
   int end = list.getModel().getSize() - 1;
   if (end >= 0) {
     list.setSelectionInterval(start, end);
   }
 }

}</source>

Select the first item

   <source lang="java">

import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   int start = 0;
   int end = 0;
   list.setSelectionInterval(start, end);
 }

}</source>

Setting the Selected Items in a JList Component

   <source lang="java">

import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   // Select the second item
   int start = 1;
   int end = 1;
   list.setSelectionInterval(start, end);
 }

}</source>

Setting the Selection Mode of a JList Component

   <source lang="java">

import javax.swing.DefaultListSelectionModel; import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   // Get the current selection model mode
   int mode = list.getSelectionMode(); // MULTIPLE_INTERVAL_SELECTION
   // Only one item can be selected
   list.setSelectionMode(DefaultListSelectionModel.SINGLE_SELECTION);
 }

}</source>

The selected items must be in a contiguous range

   <source lang="java">

import javax.swing.DefaultListSelectionModel; import javax.swing.JList; public class Main {

 public static void main(String[] argv) throws Exception {
   String[] items = { "A", "B", "C", "D" };
   JList list = new JList(items);
   list.setSelectionMode(DefaultListSelectionModel.SINGLE_INTERVAL_SELECTION);
 }

}</source>