Java Tutorial/Swing/JList Model
Содержание
- 1 Adding and Removing an Item in a JList Component
- 2 Append an item
- 3 Create a list that allows adds and removes
- 4 DefaultListModel and JList
- 5 extends AbstractListModel
- 6 extends DefaultListModel
- 7 Getting the Items in a JList Component
- 8 Insert an item at the beginning
- 9 JList: ListModel and ListSelectionModel. The ListModel handles data. ListSelectionModel works with the GUI.
- 10 Methods are used to remove items
- 11 Set method replaces an item
- 12 SortedListModel: sortable JList
Adding and Removing an Item in a JList Component
<source lang="java">
import javax.swing.DefaultListModel; import javax.swing.JList; public class Main {
public static void main(String[] argv) throws Exception {
DefaultListModel model = new DefaultListModel();
JList list = new JList(model);
// Initialize the list with items
String[] items = { "A", "B", "C", "D" };
for (int i = 0; i < items.length; i++) {
model.add(i, items[i]);
}
}
}</source>
Append an item
<source lang="java">
import javax.swing.DefaultListModel; import javax.swing.JList; public class Main {
public static void main(String[] argv) throws Exception {
// Create a list that allows adds and removes
DefaultListModel model = new DefaultListModel();
JList list = new JList(model);
int pos = list.getModel().getSize();
model.add(pos, "E");
}
}</source>
Create a list that allows adds and removes
<source lang="java">
import javax.swing.DefaultListModel; import javax.swing.JList; public class Main {
public static void main(String[] argv) throws Exception {
DefaultListModel model = new DefaultListModel();
JList list = new JList(model);
int pos = 0;
model.add(pos, "a");
}
}</source>
DefaultListModel and JList
<source lang="java">
/*
* Copyright (c) 1995 - 2008 Sun Microsystems, Inc. All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * - Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * - Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * - Neither the name of Sun Microsystems nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */
import java.awt.BorderLayout; import java.awt.Toolkit; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.BorderFactory; import javax.swing.Box; import javax.swing.BoxLayout; import javax.swing.DefaultListModel; import javax.swing.JButton; import javax.swing.JComponent; import javax.swing.JFrame; import javax.swing.JList; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.JSeparator; import javax.swing.JTextField; import javax.swing.ListSelectionModel; import javax.swing.SwingConstants; import javax.swing.event.DocumentEvent; import javax.swing.event.DocumentListener; import javax.swing.event.ListSelectionEvent; import javax.swing.event.ListSelectionListener; /* 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("Debbie Scott");
listModel.addElement("Scott Hommel");
listModel.addElement("Sharon Zakhour");
// Create the list and put it in a scroll pane.
list = new JList(listModel);
list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
list.setSelectedIndex(0);
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();
}
});
}
}</source>
extends AbstractListModel
<source lang="java">
import java.awt.BorderLayout; import java.awt.Dimension; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import javax.swing.AbstractListModel; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JList; import javax.swing.JScrollPane; public class JBenchFrame extends JFrame {
BorderLayout borderLayout1 = new BorderLayout();
JList list1 = new JList();
JButton fillButton = new JButton();
public static void main(String[] args) {
JBenchFrame bm = new JBenchFrame();
}
public JBenchFrame() {
this.getContentPane().setLayout(borderLayout1);
this.setSize(new Dimension(400, 300));
fillButton.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
ListData ld = new ListData();
long tmStart = System.currentTimeMillis();
list1.setModel(ld);
list1.repaint();
long tmEnd = System.currentTimeMillis();
System.out.println(tmEnd - tmStart);
}
});
fillButton.setText("Fill");
this.getContentPane().add(new JScrollPane(list1), BorderLayout.CENTER);
this.getContentPane().add(fillButton, BorderLayout.SOUTH);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setVisible(true);
}
} class ListData extends AbstractListModel {
String[] strings = new String[10000];
public ListData() {
for (int i = 0; i < 10000; i++) {
strings[i] = "bob" + i;
}
}
public int getSize() {
return strings.length;
}
public Object getElementAt(int index) {
return strings[index];
}
}</source>
extends DefaultListModel
<source lang="java">
import java.awt.BorderLayout; import java.awt.event.WindowAdapter; import java.awt.event.WindowEvent; import javax.swing.DefaultListModel; import javax.swing.JFrame; import javax.swing.JList; import javax.swing.JScrollPane; class MyListModel extends DefaultListModel {
protected int[] count = new int[100];
public Object getElementAt(int index) {
if (index < 100) {
count[index]++;
}
return super.elementAt(index);
}
public void dump() {
for (int i = 0; i < 100; i++) {
if (count[i] != 0) {
System.out.println(i + "\t" + count[i] + "\t\t" + elementAt(i));
}
}
}
} public class Main extends JFrame {
MyListModel model = new MyListModel();
public Main() {
for (int i = 0; i < 25; i++) {
model.addElement("A" + i);
}
JList list = new JList(model);
getContentPane().add(new JScrollPane(list), BorderLayout.CENTER);
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
model.dump();
System.exit(0);
}
});
pack();
setVisible(true);
}
public static void main(String arg[]) {
new Main();
}
}</source>
Getting the 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 number of items in the list
int size = list.getModel().getSize(); // 4
// Get all item objects
for (int i = 0; i < size; i++) {
Object item = list.getModel().getElementAt(i);
}
}
}</source>
Insert an item at the beginning
<source lang="java">
import javax.swing.DefaultListModel; import javax.swing.JList; public class Main {
public static void main(String[] argv) throws Exception {
DefaultListModel model = new DefaultListModel();
JList list = new JList(model);
int pos = 0;
model.add(pos, "a");
}
}</source>
JList: ListModel and ListSelectionModel. The ListModel handles data. ListSelectionModel works with the GUI.
<source lang="java">
import java.awt.BorderLayout; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.awt.event.MouseAdapter; import java.awt.event.MouseEvent; import javax.swing.BorderFactory; import javax.swing.BoxLayout; import javax.swing.DefaultListModel; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.JList; import javax.swing.JOptionPane; import javax.swing.JPanel; import javax.swing.JScrollPane; import javax.swing.ListSelectionModel; public class List {
public static void main(String[] args) {
final DefaultListModel model = new DefaultListModel();
final JList list = new JList(model);
JFrame f = new JFrame();
f.setTitle("JList models");
model.addElement("A");
model.addElement("B");
model.addElement("C");
model.addElement("D");
model.addElement("E");
JPanel panel = new JPanel();
panel.setLayout(new BoxLayout(panel, BoxLayout.X_AXIS));
JPanel leftPanel = new JPanel();
JPanel rightPanel = new JPanel();
leftPanel.setLayout(new BorderLayout());
rightPanel.setLayout(new BoxLayout(rightPanel, BoxLayout.Y_AXIS));
list.setSelectionMode(ListSelectionModel.SINGLE_SELECTION);
list.setBorder(BorderFactory.createEmptyBorder(2, 2, 2, 2));
list.addMouseListener(new MouseAdapter() {
public void mouseClicked(MouseEvent e) {
if (e.getClickCount() == 2) {
int index = list.locationToIndex(e.getPoint());
Object item = model.getElementAt(index);
String text = JOptionPane.showInputDialog("Rename item", item);
String newitem = "";
if (text != null)
newitem = text.trim();
else
return;
if (!newitem.isEmpty()) {
model.remove(index);
model.add(index, newitem);
ListSelectionModel selmodel = list.getSelectionModel();
selmodel.setLeadSelectionIndex(index);
}
}
}
});
leftPanel.setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
leftPanel.add(new JScrollPane(list));
JButton removeall = new JButton("Remove All");
JButton add = new JButton("Add");
JButton rename = new JButton("Rename");
JButton delete = new JButton("Delete");
add.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
String text = JOptionPane.showInputDialog("Add a new item");
String item = null;
if (text != null)
item = text.trim();
else
return;
if (!item.isEmpty())
model.addElement(item);
}
});
delete.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent event) {
ListSelectionModel selmodel = list.getSelectionModel();
int index = selmodel.getMinSelectionIndex();
if (index >= 0)
model.remove(index);
}
});
rename.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
ListSelectionModel selmodel = list.getSelectionModel();
int index = selmodel.getMinSelectionIndex();
if (index == -1)
return;
Object item = model.getElementAt(index);
String text = JOptionPane.showInputDialog("Rename item", item);
String newitem = null;
if (text != null) {
newitem = text.trim();
} else
return;
if (!newitem.isEmpty()) {
model.remove(index);
model.add(index, newitem);
}
}
});
removeall.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
model.clear();
}
});
rightPanel.add(add);
rightPanel.add(rename);
rightPanel.add(delete);
rightPanel.add(removeall);
rightPanel.setBorder(BorderFactory.createEmptyBorder(0, 0, 0, 20));
panel.add(leftPanel);
panel.add(rightPanel);
f.add(panel);
f.setSize(350, 250);
f.setLocationRelativeTo(null);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
}</source>
Methods are used to remove items
<source lang="java">
import javax.swing.DefaultListModel; import javax.swing.JList; public class Main {
public static void main(String[] argv) throws Exception {
DefaultListModel model = new DefaultListModel();
JList list = new JList(model);
// Remove the first item
int pos = 0;
model.remove(pos);
// Remove the last item
pos = model.getSize() - 1;
if (pos >= 0) {
model.remove(pos);
}
// Remove all items
model.clear();
}
}</source>
Set method replaces an item
<source lang="java">
import javax.swing.DefaultListModel; import javax.swing.JList; public class Main {
public static void main(String[] argv) throws Exception {
DefaultListModel model = new DefaultListModel();
JList list = new JList(model);
// Replace the 2nd item
int pos = 1;
model.set(pos, "b");
}
}</source>
SortedListModel: sortable JList
<source lang="java">
import java.awt.BorderLayout; import javax.swing.JFrame; import javax.swing.JList; import javax.swing.JScrollPane; import javax.swing.*; import java.util.*; class SortedListModel extends AbstractListModel {
SortedSet<Object> model;
public SortedListModel() {
model = new TreeSet<Object>();
}
public int getSize() {
return model.size();
}
public Object getElementAt(int index) {
return model.toArray()[index];
}
public void add(Object element) {
if (model.add(element)) {
fireContentsChanged(this, 0, getSize());
}
}
public void addAll(Object elements[]) {
Collection<Object> c = Arrays.asList(elements);
model.addAll(c);
fireContentsChanged(this, 0, getSize());
}
public void clear() {
model.clear();
fireContentsChanged(this, 0, getSize());
}
public boolean contains(Object element) {
return model.contains(element);
}
public Object firstElement() {
return model.first();
}
public Iterator iterator() {
return model.iterator();
}
public Object lastElement() {
return model.last();
}
public boolean removeElement(Object element) {
boolean removed = model.remove(element);
if (removed) {
fireContentsChanged(this, 0, getSize());
}
return removed;
}
}
public class JListLocationToIndexSample {
public static void main(String args[]) {
SortedListModel model = new SortedListModel();
model.add("A");
model.add("C");
model.add("Z");
model.add("B");
JFrame frame = new JFrame("Selecting JList");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JList jlist = new JList(model);
JScrollPane scrollPane1 = new JScrollPane(jlist);
frame.add(scrollPane1, BorderLayout.CENTER);
frame.setSize(350, 200);
frame.setVisible(true);
}
}</source>
