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 javax.swing.plaf.*; import javax.accessibility.*; import java.beans.BeanProperty; import java.io.ObjectOutputStream; import java.io.ObjectInputStream; import java.io.IOException; import java.util.Objects; /** * Used to display a "Tip" for a Component. Typically components provide api * to automate the process of using <code>ToolTip</code>s. * For example, any Swing component can use the <code>JComponent</code> * <code>setToolTipText</code> method to specify the text * for a standard tooltip. A component that wants to create a custom * <code>ToolTip</code> * display can override <code>JComponent</code>'s <code>createToolTip</code> * method and use a subclass of this class. * <p> * See <a href="https://docs.oracle.com/javase/tutorial/uiswing/components/tooltip.html">How to Use Tool Tips</a> * in <em>The Java Tutorial</em> * for further documentation. * <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}. * * @see JComponent#setToolTipText * @see JComponent#createToolTip * @author Dave Moore * @author Rich Shiavi * @since 1.2 */ @SuppressWarnings("serial") public class JToolTip extends JComponent implements Accessible { /** * @see #getUIClassID * @see #readObject */ private static final String uiClassID = "ToolTipUI"; String tipText; JComponent component; /** Creates a tool tip. */ public JToolTip() { setOpaque(true); updateUI(); } /** * Returns the L&F object that renders this component. * * @return the <code>ToolTipUI</code> object that renders this component */ public ToolTipUI getUI() { return (ToolTipUI) ui; } /** * Resets the UI property to a value from the current look and feel. * * @see JComponent#updateUI */ public void updateUI() { setUI((ToolTipUI) UIManager.getUI(this)); } /** * Returns the name of the L&F class that renders this component. * * @return the string "ToolTipUI" * @see JComponent#getUIClassID * @see UIDefaults#getUI */ public String getUIClassID() { return uiClassID; } /** * Sets the text to show when the tool tip is displayed. * The string <code>tipText</code> may be <code>null</code>. * * @param tipText the <code>String</code> to display */ @BeanProperty(preferred = true, description = "Sets the text of the tooltip") public void setTipText(String tipText) { String oldValue = this.tipText; this.tipText = tipText; firePropertyChange("tiptext", oldValue, tipText); if (!Objects.equals(oldValue, tipText)) { revalidate(); repaint(); } } /** * Returns the text that is shown when the tool tip is displayed. * The returned value may be <code>null</code>. * * @return the <code>String</code> that is displayed */ public String getTipText() { return tipText; } /** * Specifies the component that the tooltip describes. * The component <code>c</code> may be <code>null</code> * and will have no effect. * <p> * This is a bound property. * * @param c the <code>JComponent</code> being described * @see JComponent#createToolTip */ @BeanProperty(description = "Sets the component that the tooltip describes.") public void setComponent(JComponent c) { JComponent oldValue = this.component; component = c; firePropertyChange("component", oldValue, c); } /** * Returns the component the tooltip applies to. * The returned value may be <code>null</code>. * * @return the component that the tooltip describes * * @see JComponent#createToolTip */ public JComponent getComponent() { return component; } /** * Always returns true since tooltips, by definition, * should always be on top of all other windows. */ // package private boolean alwaysOnTop() { return true; } /** * See <code>readObject</code> and <code>writeObject</code> * in <code>JComponent</code> 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>JToolTip</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>JToolTip</code> */ protected String paramString() { String tipTextString = (tipText != null ? tipText : ""); return super.paramString() + ",tipText=" + tipTextString; } ///////////////// // Accessibility support //////////////// /** * Gets the AccessibleContext associated with this JToolTip. * For tool tips, the AccessibleContext takes the form of an * AccessibleJToolTip. * A new AccessibleJToolTip instance is created if necessary. * * @return an AccessibleJToolTip that serves as the * AccessibleContext of this JToolTip */ public AccessibleContext getAccessibleContext() { if (accessibleContext == null) { accessibleContext = new AccessibleJToolTip(); } return accessibleContext; } /** * This class implements accessibility support for the * <code>JToolTip</code> class. It provides an implementation of the * Java Accessibility API appropriate to tool tip 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 AccessibleJToolTip extends AccessibleJComponent { /** * Get the accessible description of this object. * * @return a localized String describing this object. */ public String getAccessibleDescription() { String description = accessibleDescription; // fallback to client property if (description == null) { description = (String) getClientProperty(AccessibleContext.ACCESSIBLE_DESCRIPTION_PROPERTY); } if (description == null) { description = getTipText(); } return description; } /** * Get the role of this object. * * @return an instance of AccessibleRole describing the role of the * object */ public AccessibleRole getAccessibleRole() { return AccessibleRole.TOOL_TIP; } } }