Java examples for Swing:JList
Change Selection index for JList
import java.awt.*; import java.awt.event.*; import javax.swing.*; import javax.swing.event.*; /* ListDemo.java requires no other files. */ public class ListDemo extends JPanel implements ListSelectionListener { private JList list; private DefaultListModel listModel; private static final String hireString = "Hire"; private static final String fireString = "Fire"; private JButton fireButton; private JTextField employeeName; public ListDemo() { super(new BorderLayout()); listModel = new DefaultListModel(); listModel.addElement("Jane Doe"); listModel.addElement("John Smith"); listModel.addElement("Kathy Green"); //Create the list and put it in a scroll pane. list = new JList(listModel); list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION); list.setSelectedIndex(0);//from w ww .ja v a 2s . c o m list.addListSelectionListener(this); list.setVisibleRowCount(5); JScrollPane listScrollPane = new JScrollPane(list); JButton hireButton = new JButton(hireString); HireListener hireListener = new HireListener(hireButton); hireButton.setActionCommand(hireString); hireButton.addActionListener(hireListener); hireButton.setEnabled(false); fireButton = new JButton(fireString); fireButton.setActionCommand(fireString); fireButton.addActionListener(new FireListener()); employeeName = new JTextField(10); employeeName.addActionListener(hireListener); employeeName.getDocument().addDocumentListener(hireListener); String name = listModel.getElementAt(list.getSelectedIndex()) .toString(); //Create a panel that uses BoxLayout. JPanel buttonPane = new JPanel(); buttonPane .setLayout(new BoxLayout(buttonPane, BoxLayout.LINE_AXIS)); buttonPane.add(fireButton); buttonPane.add(Box.createHorizontalStrut(5)); buttonPane.add(new JSeparator(SwingConstants.VERTICAL)); buttonPane.add(Box.createHorizontalStrut(5)); buttonPane.add(employeeName); buttonPane.add(hireButton); buttonPane.setBorder(BorderFactory.createEmptyBorder(5, 5, 5, 5)); add(listScrollPane, BorderLayout.CENTER); add(buttonPane, BorderLayout.PAGE_END); } class FireListener implements ActionListener { public void actionPerformed(ActionEvent e) { //This method can be called only if //there's a valid selection //so go ahead and remove whatever's selected. int index = list.getSelectedIndex(); listModel.remove(index); int size = listModel.getSize(); if (size == 0) { //Nobody's left, disable firing. fireButton.setEnabled(false); } else { //Select an index. if (index == listModel.getSize()) { //removed item in last position index--; } list.setSelectedIndex(index); list.ensureIndexIsVisible(index); } } } //This listener is shared by the text field and the hire button. class HireListener implements ActionListener, DocumentListener { private boolean alreadyEnabled = false; private JButton button; public HireListener(JButton button) { this.button = button; } //Required by ActionListener. public void actionPerformed(ActionEvent e) { String name = employeeName.getText(); //User didn't type in a unique name... if (name.equals("") || alreadyInList(name)) { Toolkit.getDefaultToolkit().beep(); employeeName.requestFocusInWindow(); employeeName.selectAll(); return; } int index = list.getSelectedIndex(); //get selected index if (index == -1) { //no selection, so insert at beginning index = 0; } else { //add after the selected item index++; } listModel.insertElementAt(employeeName.getText(), index); //If we just wanted to add to the end, we'd do this: //listModel.addElement(employeeName.getText()); //Reset the text field. employeeName.requestFocusInWindow(); employeeName.setText(""); //Select the new item and make it visible. list.setSelectedIndex(index); list.ensureIndexIsVisible(index); } //This method tests for string equality. You could certainly //get more sophisticated about the algorithm. For example, //you might want to ignore white space and capitalization. protected boolean alreadyInList(String name) { return listModel.contains(name); } //Required by DocumentListener. public void insertUpdate(DocumentEvent e) { enableButton(); } //Required by DocumentListener. public void removeUpdate(DocumentEvent e) { handleEmptyTextField(e); } //Required by DocumentListener. public void changedUpdate(DocumentEvent e) { if (!handleEmptyTextField(e)) { enableButton(); } } private void enableButton() { if (!alreadyEnabled) { button.setEnabled(true); } } private boolean handleEmptyTextField(DocumentEvent e) { if (e.getDocument().getLength() <= 0) { button.setEnabled(false); alreadyEnabled = false; return true; } return false; } } //This method is required by ListSelectionListener. public void valueChanged(ListSelectionEvent e) { if (e.getValueIsAdjusting() == false) { if (list.getSelectedIndex() == -1) { //No selection, disable fire button. fireButton.setEnabled(false); } else { //Selection, enable the fire button. fireButton.setEnabled(true); } } } /** * Create the GUI and show it. For thread safety, * this method should be invoked from the * event-dispatching thread. */ private static void createAndShowGUI() { //Create and set up the window. JFrame frame = new JFrame("ListDemo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); //Create and set up the content pane. JComponent newContentPane = new ListDemo(); newContentPane.setOpaque(true); //content panes must be opaque frame.setContentPane(newContentPane); //Display the window. frame.pack(); frame.setVisible(true); } public static void main(String[] args) { //Schedule a job for the event-dispatching thread: //creating and showing this application's GUI. javax.swing.SwingUtilities.invokeLater(new Runnable() { public void run() { createAndShowGUI(); } }); } } /* * Copyright (c) 1995, 2008, Oracle and/or its affiliates. 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