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.beans.ConstructorProperties; import javax.swing.plaf.*; import javax.accessibility.*; import java.io.ObjectOutputStream; import java.io.IOException; /** * An implementation of a "push" button. * <p> * Buttons 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 button has many benefits beyond directly * configuring a button. 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> * See <a href="https://docs.oracle.com/javase/tutorial/uiswing/components/button.html">How to Use Buttons, Check Boxes, and Radio Buttons</a> * in <em>The Java Tutorial</em> * for information and examples of using buttons. * <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 Jeff Dinkins * @since 1.2 */ @JavaBean(defaultProperty = "UIClassID", description = "An implementation of a \"push\" button.") @SwingContainer(false) @SuppressWarnings("serial") public class JButton extends AbstractButton implements Accessible { /** * @see #getUIClassID * @see #readObject */ private static final String uiClassID = "ButtonUI"; /** * Creates a button with no set text or icon. */ public JButton() { this(null, null); } /** * Creates a button with an icon. * * @param icon the Icon image to display on the button */ public JButton(Icon icon) { this(null, icon); } /** * Creates a button with text. * * @param text the text of the button */ @ConstructorProperties({ "text" }) public JButton(String text) { this(text, null); } /** * Creates a button where properties are taken from the * <code>Action</code> supplied. * * @param a the <code>Action</code> used to specify the new button * * @since 1.3 */ public JButton(Action a) { this(); setAction(a); } /** * Creates a button with initial text and an icon. * * @param text the text of the button * @param icon the Icon image to display on the button */ public JButton(String text, Icon icon) { // Create the model setModel(new DefaultButtonModel()); // initialize init(text, icon); } /** * Resets the UI property to a value from the current look and * feel. * * @see JComponent#updateUI */ public void updateUI() { setUI((ButtonUI) UIManager.getUI(this)); } /** * Returns a string that specifies the name of the L&F class * that renders this component. * * @return the string "ButtonUI" * @see JComponent#getUIClassID * @see UIDefaults#getUI */ @BeanProperty(bound = false, expert = true, description = "A string that specifies the name of the L&F class.") public String getUIClassID() { return uiClassID; } /** * Gets the value of the <code>defaultButton</code> property, * which if <code>true</code> means that this button is the current * default button for its <code>JRootPane</code>. * Most look and feels render the default button * differently, and may potentially provide bindings * to access the default button. * * @return the value of the <code>defaultButton</code> property * @see JRootPane#setDefaultButton * @see #isDefaultCapable */ @BeanProperty(bound = false, description = "Whether or not this button is the default button") public boolean isDefaultButton() { JRootPane root = SwingUtilities.getRootPane(this); if (root != null) { return root.getDefaultButton() == this; } return false; } /** * Gets the value of the <code>defaultCapable</code> property. * * @return the value of the <code>defaultCapable</code> property * @see #setDefaultCapable * @see #isDefaultButton * @see JRootPane#setDefaultButton */ public boolean isDefaultCapable() { return defaultCapable; } /** * Sets the <code>defaultCapable</code> property, * which determines whether this button can be * made the default button for its root pane. * The default value of the <code>defaultCapable</code> * property is <code>true</code> unless otherwise * specified by the look and feel. * * @param defaultCapable <code>true</code> if this button will be * capable of being the default button on the * <code>RootPane</code>; otherwise <code>false</code> * @see #isDefaultCapable */ @BeanProperty(visualUpdate = true, description = "Whether or not this button can be the default button") public void setDefaultCapable(boolean defaultCapable) { boolean oldDefaultCapable = this.defaultCapable; this.defaultCapable = defaultCapable; firePropertyChange("defaultCapable", oldDefaultCapable, defaultCapable); } /** * Overrides <code>JComponent.removeNotify</code> to check if * this button is currently set as the default button on the * <code>RootPane</code>, and if so, sets the <code>RootPane</code>'s * default button to <code>null</code> to ensure the * <code>RootPane</code> doesn't hold onto an invalid button reference. */ public void removeNotify() { JRootPane root = SwingUtilities.getRootPane(this); if (root != null && root.getDefaultButton() == this) { root.setDefaultButton(null); } super.removeNotify(); } /** * 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 <code>JButton</code>. * 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 <code>JButton</code> */ protected String paramString() { String defaultCapableString = (defaultCapable ? "true" : "false"); return super.paramString() + ",defaultCapable=" + defaultCapableString; } ///////////////// // Accessibility support //////////////// /** * Gets the <code>AccessibleContext</code> associated with this * <code>JButton</code>. For <code>JButton</code>s, * the <code>AccessibleContext</code> takes the form of an * <code>AccessibleJButton</code>. * A new <code>AccessibleJButton</code> instance is created if necessary. * * @return an <code>AccessibleJButton</code> that serves as the * <code>AccessibleContext</code> of this <code>JButton</code> */ @BeanProperty(bound = false, expert = true, description = "The AccessibleContext associated with this Button.") public AccessibleContext getAccessibleContext() { if (accessibleContext == null) { accessibleContext = new AccessibleJButton(); } return accessibleContext; } /** * This class implements accessibility support for the * <code>JButton</code> class. It provides an implementation of the * Java Accessibility API appropriate to button 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") protected class AccessibleJButton extends AccessibleAbstractButton { /** * Get the role of this object. * * @return an instance of AccessibleRole describing the role of the * object * @see AccessibleRole */ public AccessibleRole getAccessibleRole() { return AccessibleRole.PUSH_BUTTON; } } // inner class AccessibleJButton }