Java tutorial
/* * Copyright (c) 1997, 2015, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package javax.swing; import java.beans.JavaBean; import java.beans.BeanProperty; import java.io.ObjectOutputStream; import java.io.IOException; import javax.accessibility.*; /** * A menu item that can be selected or deselected. If selected, the menu * item typically appears with a checkmark next to it. If unselected or * deselected, the menu item appears without a checkmark. Like a regular * menu item, a check box menu item can have either text or a graphic * icon associated with it, or both. * <p> * Either <code>isSelected</code>/<code>setSelected</code> or * <code>getState</code>/<code>setState</code> can be used * to determine/specify the menu item's selection state. The * preferred methods are <code>isSelected</code> and * <code>setSelected</code>, which work for all menus and buttons. * The <code>getState</code> and <code>setState</code> methods exist for * compatibility with other component sets. * <p> * Menu items can be configured, and to some degree controlled, by * <code><a href="Action.html">Action</a></code>s. Using an * <code>Action</code> with a menu item has many benefits beyond directly * configuring a menu item. Refer to <a href="Action.html#buttonActions"> * Swing Components Supporting <code>Action</code></a> for more * details, and you can find more information in <a * href="https://docs.oracle.com/javase/tutorial/uiswing/misc/action.html">How * to Use Actions</a>, a section in <em>The Java Tutorial</em>. * <p> * Some times it is required to select several check box menu items from a menu. * In this case it is useful that clicking on one check box menu item does not * close the menu. Such behavior can be controlled either by client * {@link JComponent#putClientProperty} or the Look and Feel * {@link UIManager#put} property named * {@code "CheckBoxMenuItem.doNotCloseOnMouseClick"}. The default value is * {@code false}. Setting the property to {@code true} prevents the menu from * closing when it is clicked by the mouse. If the client property is set its * value is always used; otherwise the {@literal L&F} property is queried. * Note: some {@code L&F}s may ignore this property. All built-in {@code L&F}s * inherit this behaviour. * <p> * For further information and examples of using check box menu items, * see <a href="https://docs.oracle.com/javase/tutorial/uiswing/components/menu.html">How to Use Menus</a>, * a section in <em>The Java Tutorial.</em> * <p> * <strong>Warning:</strong> Swing is not thread safe. For more * information see <a * href="package-summary.html#threading">Swing's Threading * Policy</a>. * <p> * <strong>Warning:</strong> * Serialized objects of this class will not be compatible with * future Swing releases. The current serialization support is * appropriate for short term storage or RMI between applications running * the same version of Swing. As of 1.4, support for long term storage * of all JavaBeans™ * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. * * @author Georges Saab * @author David Karlton * @since 1.2 */ @JavaBean(description = "A menu item which can be selected or deselected.") @SwingContainer(false) @SuppressWarnings("serial") // Same-version serialization only public class JCheckBoxMenuItem extends JMenuItem implements SwingConstants, Accessible { /** * @see #getUIClassID * @see #readObject */ private static final String uiClassID = "CheckBoxMenuItemUI"; /** * Creates an initially unselected check box menu item with no set text or icon. */ public JCheckBoxMenuItem() { this(null, null, false); } /** * Creates an initially unselected check box menu item with an icon. * * @param icon the icon of the {@code JCheckBoxMenuItem}. */ public JCheckBoxMenuItem(Icon icon) { this(null, icon, false); } /** * Creates an initially unselected check box menu item with text. * * @param text the text of the {@code JCheckBoxMenuItem} */ public JCheckBoxMenuItem(String text) { this(text, null, false); } /** * Creates a menu item whose properties are taken from the * Action supplied. * * @param a the action of the {@code JCheckBoxMenuItem} * @since 1.3 */ public JCheckBoxMenuItem(Action a) { this(); setAction(a); } /** * Creates an initially unselected check box menu item with the specified text and icon. * * @param text the text of the {@code JCheckBoxMenuItem} * @param icon the icon of the {@code JCheckBoxMenuItem} */ public JCheckBoxMenuItem(String text, Icon icon) { this(text, icon, false); } /** * Creates a check box menu item with the specified text and selection state. * * @param text the text of the check box menu item. * @param b the selected state of the check box menu item */ public JCheckBoxMenuItem(String text, boolean b) { this(text, null, b); } /** * Creates a check box menu item with the specified text, icon, and selection state. * * @param text the text of the check box menu item * @param icon the icon of the check box menu item * @param b the selected state of the check box menu item */ public JCheckBoxMenuItem(String text, Icon icon, boolean b) { super(text, icon); setModel(new JToggleButton.ToggleButtonModel()); setSelected(b); setFocusable(false); } /** * Returns the name of the L&F class * that renders this component. * * @return the string "CheckBoxMenuItemUI" * @see JComponent#getUIClassID * @see UIDefaults#getUI */ @BeanProperty(bound = false) public String getUIClassID() { return uiClassID; } /** * Returns the selected-state of the item. This method * exists for AWT compatibility only. New code should * use isSelected() instead. * * @return true if the item is selected */ public boolean getState() { return isSelected(); } /** * Sets the selected-state of the item. This method * exists for AWT compatibility only. New code should * use setSelected() instead. * * @param b a boolean value indicating the item's * selected-state, where true=selected */ @BeanProperty(bound = false, hidden = true, description = "The selection state of the check box menu item") public synchronized void setState(boolean b) { setSelected(b); } /** * Returns an array (length 1) containing the check box menu item * label or null if the check box is not selected. * * @return an array containing one Object -- the text of the menu item * -- if the item is selected; otherwise null */ @BeanProperty(bound = false) public Object[] getSelectedObjects() { if (isSelected() == false) return null; Object[] selectedObjects = new Object[1]; selectedObjects[0] = getText(); return selectedObjects; } /** * See readObject() and writeObject() in JComponent for more * information about serialization in Swing. */ private void writeObject(ObjectOutputStream s) throws IOException { s.defaultWriteObject(); if (getUIClassID().equals(uiClassID)) { byte count = JComponent.getWriteObjCounter(this); JComponent.setWriteObjCounter(this, --count); if (count == 0 && ui != null) { ui.installUI(this); } } } /** * Returns a string representation of this JCheckBoxMenuItem. This method * is intended to be used only for debugging purposes, and the * content and format of the returned string may vary between * implementations. The returned string may be empty but may not * be <code>null</code>. * * @return a string representation of this JCheckBoxMenuItem. */ protected String paramString() { return super.paramString(); } /** * Overriden to return true, JCheckBoxMenuItem supports * the selected state. */ boolean shouldUpdateSelectedStateFromAction() { return true; } ///////////////// // Accessibility support //////////////// /** * Gets the AccessibleContext associated with this JCheckBoxMenuItem. * For JCheckBoxMenuItems, the AccessibleContext takes the form of an * AccessibleJCheckBoxMenuItem. * A new AccessibleJCheckBoxMenuItem instance is created if necessary. * * @return an AccessibleJCheckBoxMenuItem that serves as the * AccessibleContext of this AccessibleJCheckBoxMenuItem */ @BeanProperty(bound = false) public AccessibleContext getAccessibleContext() { if (accessibleContext == null) { accessibleContext = new AccessibleJCheckBoxMenuItem(); } return accessibleContext; } /** * This class implements accessibility support for the * <code>JCheckBoxMenuItem</code> class. It provides an implementation * of the Java Accessibility API appropriate to checkbox menu item * user-interface elements. * <p> * <strong>Warning:</strong> * Serialized objects of this class will not be compatible with * future Swing releases. The current serialization support is * appropriate for short term storage or RMI between applications running * the same version of Swing. As of 1.4, support for long term storage * of all JavaBeans™ * has been added to the <code>java.beans</code> package. * Please see {@link java.beans.XMLEncoder}. */ @SuppressWarnings("serial") // Same-version serialization only protected class AccessibleJCheckBoxMenuItem extends AccessibleJMenuItem { /** * Get the role of this object. * * @return an instance of AccessibleRole describing the role of the * object */ public AccessibleRole getAccessibleRole() { return AccessibleRole.CHECK_BOX; } } // inner class AccessibleJCheckBoxMenuItem }