📄 problems.html
字号:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2//EN"><html> <head> <title>Solving Common Event-Handling Problems (The Java™ Tutorials > Creating a GUI with JFC/Swing > Writing Event Listeners)</title><style type="text/css"> .FigureCaption { margin-left: 1in; margin-right: 1in; font-family: sans-serif; font-size: smaller; text-align: justify; } #TopBar_bl { background: url(../../images/java_bar_bl.gif) 0 100% no-repeat; width: 100%; height: 60px; } #TopBar_br { background: url(../../images/java_bar_br.gif) 100% 100% no-repeat; width: 100%; height: 60px; } #TopBar_tl { background: url(../../images/java_bar_tl.gif) 0 0 no-repeat; width: 100%; height: 60px; } #TopBar_tr { background: url(../../images/java_bar_tr.gif) 100% 0 no-repeat; width: 100%; height: 60px; } #TopBar { background: #35556B url(../../images/java_bar.gif); margin: 10px 10px 0 10px; height:60px; min-width:700px; color: white; font-family: sans-serif; font-weight: bold; } @media print { #BreadCrumbs, #Download { display: none; } } #TopBar_right { line-height: 14px; float: right; padding-top: 2px; padding-right: 30px; text-align: center; } @media print { #TopBar_right { display: none; } } #TopBar_right a { font-size: 12px; margin: 3px; padding: 0; } #TopBar a:visited, #TopBar a:link { color: white; text-decoration: none; } #TopBar a:hover, #TopBar a:active { background-color: white; color: #35556B; } #BreadCrumbs { padding: 4px 5px 0.5em 0; font-family: sans-serif; float: right; } #BreadCrumbs a { color: blue; } #BreadCrumbs a:visited, #BreadCrumbs a:link { text-decoration: none; } #BreadCrumbs a:hover, #BreadCrumbs a:active { text-decoration: underline; } #PageTitle { margin: 0 5px 0.5em 0; color: #E76F00; font-family: sans-serif; font-weight: bold; font-size: 20px; } .LeftBar_shown { width: 13em; float: left; margin-left: 10px; margin-top: 4px; margin-bottom: 2em; } @media print { .LeftBar_shown { display: none; } } .LeftBar_hidden { display: none; } #Footer { padding-top: 10px; padding-left: 10px; margin-right: 10px; } .NavBit { padding: 4px 5px 0.5em 0; font-family: sans-serif; } @media print { .NavBit { display: none; } } #TagNotes { text-align: right; font-size: smaller; font-family: sans-serif; } @media print { #TagNotes a:visited, #TagNotes a:link { color: #35556B; text-decoration: none; } } #Contents a, .NavBit a, #TagNotes a { color: blue } #TagNotes a:visited, #TagNotes a:link, #Contents a:visited, #Contents a:link, .NavBit a:visited, .NavBit a:link { text-decoration: none; } #TagNotes a:hover, #TagNotes a:active, #Contents a:hover, #Contents a:active, .NavBit a:hover, .NavBit a:active { text-decoration: underline; } #Contents { float: left; font-family: sans-serif; } @media print { #Contents { display: none; } } @media screen { div.PrintHeaders { display: none; } } .linkLESSON, .nolinkLESSON { margin-left: 0.5em; text-indent: -0.5em } .linkAHEAD, .nolinkAHEAD, .linkQUESTIONS, .nolinkQUESTIONS { margin-left: 1.5em; text-indent: -0.5em } .linkBHEAD, .nolinkBHEAD { margin-left: 2.5em; text-indent: -0.5em } .linkCHEAD, .nolinkCHEAD { margin-left: 3.5em; text-indent: -0.5em } .nolinkLESSON, .nolinkAHEAD, .nolinkBHEAD, .nolinkCHEAD, .nolinkQUESTIONS { font-weight: bold; color: #E76F00; } .MainFlow_indented { margin-right: 10px; margin-left: 15em; margin-bottom: 2em; } .MainFlow_wide { margin-right: 10px; margin-left: 10px; margin-bottom: 2em; } @media print { .MainFlow_indented, .MainFlow_wide { padding-top: 0; margin-top: 10px; margin-right: 10px; margin-left: 0; } } h3, h4, h5 { color: #E76F00; font-family: sans-serif; } #ToggleLeft { display: none; } /t</style><script type="text/javascript"> function leftBar() { var nameq = 'tutorial_showLeftBar=' var cookies = document.cookie.split(';'); for (var i = 0; i < cookies.length; i++) { var cookieString = cookies[i]; while (cookieString.charAt(0) == ' ') { cookieString = cookieString.substring(1, cookieString.length); } if (cookieString.indexOf(nameq) == 0) { cookieValue = cookieString.substring(nameq.length, cookieString.length); return cookieValue == 'yes'; } } return true; } function showLeft(b) { var contents = document.getElementById("LeftBar"); var main = document.getElementById("MainFlow"); var toggle = document.getElementById("ToggleLeft"); if (b) { contents.className = "LeftBar_shown"; main.className = "MainFlow_indented"; toggle.innerHTML = "Hide the TOC"; document.cookie = 'tutorial_showLeftBar=yes; path=/'; } else { contents.className = "LeftBar_hidden"; main.className = "MainFlow_wide"; toggle.innerHTML = "Show the TOC"; document.cookie = 'tutorial_showLeftBar=no; path=/'; } } function toggleLeft() { showLeft(document.getElementById("LeftBar").className == "LeftBar_hidden"); document.getElementById("ToggleLeft").blur(); } function load() { showLeft(leftBar()); document.getElementById("ToggleLeft").style.display="inline"; } </script> </head><body onload="load()"> <div id=TopBar> <div id=TopBar_tr> <div id=TopBar_tl> <div id=TopBar_br> <div id=TopBar_bl> <div id=TopBar_right> <a target="_blank" href="http://java.sun.com/javase/6/download.jsp">Download the JDK</a> <br> <a href="../../search.html" target="_blank">Search the Tutorials</a> <br> <a href="javascript:toggleLeft()" id="ToggleLeft">Hide the TOC</a> </div> </div> </div> </div> </div> </div> <div class=PrintHeaders> <b>Trail:</b> Creating a GUI with JFC/Swing <br><b>Lesson:</b> Writing Event Listeners </div> <div id=LeftBar class=LeftBar_shown> <div id=Contents> <div class="linkLESSON"><a href="index.html">Writing Event Listeners</a></div><div class="linkAHEAD"><a href="intro.html">Introduction to Event Listeners</a></div><div class="linkAHEAD"><a href="generalrules.html">General Information about Writing Event Listeners</a></div><div class="linkAHEAD"><a href="eventsandcomponents.html">Listeners Supported by Swing Components</a></div><div class="linkAHEAD"><a href="handling.html">Implementing Listeners for Commonly Handled Events</a></div><div class="linkBHEAD"><a href="actionlistener.html">How to Write an Action Listener</a></div><div class="linkBHEAD"><a href="caretlistener.html">How to Write a Caret Listener</a></div><div class="linkBHEAD"><a href="changelistener.html">How to Write a Change Listener</a></div><div class="linkBHEAD"><a href="componentlistener.html">How to Write a Component Listener</a></div><div class="linkBHEAD"><a href="containerlistener.html">How to Write a Container Listener</a></div><div class="linkBHEAD"><a href="documentlistener.html">How to Write a Document Listener</a></div><div class="linkBHEAD"><a href="focuslistener.html">How to Write a Focus Listener</a></div><div class="linkBHEAD"><a href="internalframelistener.html">How to Write an Internal Frame Listener</a></div><div class="linkBHEAD"><a href="itemlistener.html">How to Write an Item Listener</a></div><div class="linkBHEAD"><a href="keylistener.html">How to Write a Key Listener</a></div><div class="linkBHEAD"><a href="listdatalistener.html">How to Write a List Data Listener</a></div><div class="linkBHEAD"><a href="listselectionlistener.html">How to Write a List Selection Listener</a></div><div class="linkBHEAD"><a href="mouselistener.html">How to Write a Mouse Listener</a></div><div class="linkBHEAD"><a href="mousemotionlistener.html">How to Write a Mouse-Motion Listener</a></div><div class="linkBHEAD"><a href="mousewheellistener.html">How to Write a Mouse-Wheel Listener</a></div><div class="linkBHEAD"><a href="propertychangelistener.html">How to Write a Property Change Listener</a></div><div class="linkBHEAD"><a href="tablemodellistener.html">How to Write a Table Model Listener</a></div><div class="linkBHEAD"><a href="treeexpansionlistener.html">How to Write a Tree Expansion Listener</a></div><div class="linkBHEAD"><a href="treemodellistener.html">How to Write a Tree Model Listener</a></div><div class="linkBHEAD"><a href="treeselectionlistener.html">How to Write a Tree Selection Listener</a></div><div class="linkBHEAD"><a href="treewillexpandlistener.html">How to Write a Tree-Will-Expand Listener</a></div><div class="linkBHEAD"><a href="undoableeditlistener.html">How to Write an Undoable Edit Listener</a></div><div class="linkBHEAD"><a href="windowlistener.html">How to Write Window Listeners</a></div><div class="linkAHEAD"><a href="api.html">Listener API Table</a></div><div class="nolinkAHEAD">Solving Common Event-Handling Problems</div></div> </div> <div id=MainFlow class=MainFlow_indented> <span id=BreadCrumbs> <a href=../../index.html target=_top>Home Page</a> > <a href=../index.html target=_top>Creating a GUI with JFC/Swing</a> > <a href=index.html target=_top>Writing Event Listeners</a> </span> <div class=NavBit> <a target=_top href=api.html>« Previous</a> • <a target=_top href=../TOC.html>Trail</a> • <a target=_top href=../QandE/questions-ch5.html>Next »</a> </div> <div id=PageTitle>Solving Common Event-Handling Problems</div> <blockquote>This section discusses problems that you might encounter while handling events.<p><strong>Problem:</strong>I'm trying to handle certain events from a component,but the component isn't generating the events it should.<ul><li> First, make sure you registered the right kind of listener to detect the events. See whether another kind of listener might detect the kind of events you need.<li> Make sure you registered the listener on the right object.<li> Did you implement the event handler correctly? For example, if you extended an adapter class, then make sure you used the right method signature. Make sure each event-handling method is <code>public void</code>, that the name spelled right and that the argument is of the right type.<li> If you still think that the component isn't generating the events it should, check the <a class="OutsideLink" target="_blank" href="http://developer.java.sun.com/">Java Developer Connection</a> to see whether this is a known bug.</ul><p><strong>Problem:</strong>My combo box isn't generating low-level events such as focus events.<ul><li> Combo boxes are compound components — components implemented using multiple components. For this reason, combo boxes don't fire the low-level events that simple components fire. For more information, see <a class="TutorialLink" target="_top" href="../components/combobox.html#listeners">Handling Events on a Combo Box</a>.</ul><p><strong>Problem:</strong>The document for an editor pane (or text pane)isn't firing document events.<ul><li> The document instance for an editor pane or text pane might change when loading text from a URL. Thus, your listeners might be listening for events on an unused document. For example, if you load an editor pane or text pane with HTML that was previously loaded with plain text, the document will change to an <code>HTMLDocument</code> instance. If your program dynamically loads text into an editor pane or text pane, make sure the code adjusts for possible changes to the document (re-register document listeners on the new document, and so on).</ul>If you don't see your problem in this list, see<a class="TutorialLink" target="_top" href="../components/problems.html">Solving Common Component Problems</a>. </blockquote> <div class=NavBit> <a target=_top href=api.html>« Previous</a> • <a target=_top href=../TOC.html>Trail</a> • <a target=_top href=../QandE/questions-ch5.html>Next »</a> </div> </div> <div id=Footer><div id=TagNotes> Problems with the examples? Try <a target="_blank" href=../../information/run-examples.html>Compiling and Running the Examples: FAQs</a>. <br> Complaints? Compliments? Suggestions? <a target="_blank" href="http://developer.sun.com/contact/tutorial_feedback.jsp">Give us your feedback</a>.<br><br> <a target="_blank" href="../../information/copyright.html">Copyright</a> 1995-2006 Sun Microsystems, Inc. All rights reserved. <span id=Download></span></div> </div> <div class=PrintHeaders> <b>Previous page:</b> Listener API Table <br><b>Next page:</b> Questions and Exercises: Writing Event Listeners </div> </body></html> ⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -