events.html.svn-base
来自「j2me设计的界面包」· SVN-BASE 代码 · 共 374 行
SVN-BASE
374 行
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"><html lang="en-US"><head><meta http-equiv="content-type" content="text/html; charset=UTF-8"><title>LWUIT Tutorial - Event Handling</title><meta name="keywords" content="PUT, YOUR, PAGE-SPECIFIC, KEYWORDS, HERE"><meta name="description" content="PUT YOUR PAGE-SPECIFIC DESCRIPTION HERE"><meta http-equiv="content-language" content="en-US"><link rel="stylesheet" type="text/css" href="style/default.css"><link rel="stylesheet" type="text/css" href="style/local/www.css"><link rel="shortcut icon" href="/favicon.ico" type="image/x-icon"><link rel="search" type="application/opensearchdescription+xml" title="Sun Search" href="http://search.sun.com/search/resources/onesearch/default-osd.xml"><script type="text/javascript" src="/js/sniff.js"></script><script type="text/javascript" src="/js/menucontent.js"></script><script type="text/javascript" src="/js/menucode.js"></script></head><body bgcolor="#ffffff"><div class="a0 a0v0" id="a0v0"><!--stopindex--><a name="top"></a><!-- BEGIN A1 COMPONENT V.0 --><!--<div class="a1 a1r2"><div class="a1v0"><a href="#skip2content" class="skiplink">Skip to Content</a><span class="toolbarlinks"><a href="/java/">Java</a><a href="/software/solaris/">Solaris</a><a href="/communities/" class="dividelink">Communities</a><a href="/aboutsun/">About Sun</a><a href="/sales/" class="dividelink">How to Buy</a><a href="https://portal.sun.com/portal/dt/">My Account</a><a href="http://shop.sun.com/cart/" class="a1cart lastlink">Cart</a></span><span class="siteid"><span>United States</span><a href="/worldwide/">Worldwide</a></span></div></div>--><!-- END A1 COMPONENT V.0 --><!-- BEGIN A2 COMPONENT V.0 --><div class="a2w0"><div class="a2" id="a2v0"><div class="a2w1"><div class="a2w2"><div class="a2w3"><div class="a2w4"><div class="a2topiclinks"><div class="a2search"><!--<form action="/cgi-bin/search/index.cgi"><input type="hidden" name="charset" value="UTF-8"><input id="searchfield" type="text" name="search" value="Search"><input id="searchbttn" type="image" border="0" src="/im/a2_bttn_search.gif" alt="Submit Search"></form>--></div><a href="http://www.sun.com/" title="Sun Microsystems Home Page" id="sunlogo"><img src="http://www.sun.com/im/a.gif" alt="Sun Microsystems Home Page" width="98" height="58" border="0" /></a><!--<ul id="mtopics"><li id="mtopic1"><a id="glink1" class="tpclink a2menu" title="See All Products" href="/products/">Products</a></li><li id="mtopic2"><a id="glink2" class="tpclink a2menu" title="See All Downloads" href="/download/">Downloads</a></li><li id="mtopic3"><a id="glink3" class="tpclink a2menu" title="See All Services & Solutions" href="/servicessolutions/">Services & Solutions</a></li><li id="mtopic4"><a id="glink4" class="tpclink a2menu" title="See All Support" href="http://sunsolve.sun.com/">Support</a></li><li id="mtopic5"><a id="glink5" class="tpclink a2menu" title="See All Training" href="/training/">Training</a></li><li id="mtopic6"><a id="glink6" class="tpclink a2menu" title="See All Developer" href="http://developers.sun.com/">Developer</a></li></ul>--></div></div></div></div></div></div></div><!-- END A2 COMPONENT V.0 --><!-- BEGIN BREADCRUMB --><table width="100%"> <tr> <td align="left"><div align="left" id="breadcrumb"><a href="transitions.html"><<Previous</a></div></td> <td align="center"><div align="center" id="breadcrumb"><a href="index.html">Top</a></div></td> <td align="right"><div align="right" id="breadcrumb"><a href="styling.html">Next>></a></div></td> </tr></table><!-- END BREADCRUMB --><!-- BEGIN PAGETITLE TWO LINE --><div class="pagetitle2">LWUIT Tutorial</div><div class="smallpagetitle"><h1>Event Handling</h1></div><!-- END PAGETITLE TWO LINE --><!-- BEGIN WRAPPER TABLE, 1 COLUMN, MAIN --><table border="0" cellpadding="0" cellspacing="10" width="100%"><tr><td width="100%" valign="top"><!-- BEGIN CENTRAL COLUMN COMPONENTS --><a name="skip2content"> </a><!--startindex--><!-- ============ --><!-- MAIN CONTENT --><!-- ============ --><div class="pc0"><div class="pc0v4"><h1>Responding to Button Clicks</h1><p>LWUIT notifies your application about events via listener interfaces. Yourapplication provides implementations of the appropriate interface, registersthem with LWUIT, and takes action when an event occurs.</p><p>To respond to a button press, for example, your application needs to dotwo things:</p><ol><li>Define an implementation of <code>ActionListener</code>.</li><li>Pass an instance of the <code>ActionListener</code> to the <code>Button</code>'s<code>addActionListener()</code>. </li></ol><p>The following example uses an inner class to implement <code>ActionListener</code>.Every time you press the button, the label changes.</p><pre>final Form f = new Form("Events");Button button = new Button("Push me!");final Label countLabel = new Label(" ");button.addActionListener(new ActionListener() { private int c = 0; public void actionPerformed(ActionEvent ae) { c++; countLabel.setText(Integer.toString(c)); f.layoutContainer(); }});</pre><p>The call to <code>layoutContainer()</code> ensures that the label's size isadjusted correctly when the number gets bigger. For example, notice how thesize adjusts when the count goes from 9 to 10.</p><p>If you use a single listener for more than one button, you can find out whichbutton was pressed by calling the <code>ActionEvent</code>'s<code>getSource()</code> method.</p><h1>Using Commands</h1><p>LWUIT includes the concept of a <i>command</i>. A command is something thatyour user can do in your application. LWUIT decides how to show the commandon the screen and how the user makes it happen. Usually, commands areassigned to the soft buttons on a mobile phone. LWUIT will normally show commandsas labels at the bottom corners of the screen; the user can invoke them bypressing the corresponding soft button. On touch devices, the user cantouch directly on a command to invoke it.</p><p> Conceptually, commands in LWUIT closely resemble commands in MIDP. Some of the details are slightly different, but if you already understand MIDP commands, you'll have no trouble with LWUIT commands.</p><p> In LWUIT, create commands and add them to forms. Then register a listener object with the form to be notified when the user invokes a command.</p><p> This simple example creates a form and registers a listener. The listener shuts down the application when it is invoked.</p><pre>import javax.microedition.midlet.*;import com.sun.lwuit.*;import com.sun.lwuit.events.*;public class HelloLWUITMidlet extends MIDlet implements ActionListener { private Form mForm; public void startApp() { if (mForm == null) { Display.init(this); Form f = new Form("Hello, LWUIT!"); Command exitCommand = new Command("Exit"); f.addCommand(exitCommand); f.setCommandListener(this); f.show(); } } public void pauseApp() { } public void destroyApp(boolean unconditional) { } public void actionPerformed(ActionEvent ae) { destroyApp(true); notifyDestroyed(); }}</pre><p>If you add more than two commands to a form, they won't fit on the twoavailable soft buttons. In this case, one of the soft buttons will becomea menu. When the user invokes the menu, it shows a list of the rest of thecommands.</p><p>When your listener's <code>actionPerformed()</code> method must respond to morethan one command, you can find out which one was invoked by calling the<code>ActionEvent</code>'s <code>getCommand()</code> method.</p><h1>Other Event Types</h1><p>Most of your event handling will involve <code>ActionListener</code> forcommands and buttons, but LWUIT includes other useful listeners:</p><ul> <li>Use <code>DataChangedListener</code> to find out when a <code>ListModel</code> changes. Remember, <code>ListModel</code> represents the data behind a list or combo box.</li> <li>A <code>SelectionListener</code> is notified when the current selection of a <code>ListModel</code> changes.</li> <li>A <code>FocusListener</code> is notified when a component gains or loses focus.</li> <li>Finally, <code>StyleListener</code> receives notifications about changes in a component's style. The next section of this tutorial describes styles and themes.</li></ul><!-- =================== --><!-- END OF MAIN CONTENT --><!-- =================== --><!--stopindex--><!-- END CENTRAL COLUMN COMPONENTS --></td></tr><!-- BEGIN SPACER ROW --><tr><td><img src="/im/a.gif" width="780" height="1" border="0" alt="" /></td></tr><!-- END SPACER ROW --></table><!-- END WRAPPER TABLE, 1 COLUMN, MAIN --><!-- BEGIN BREADCRUMB --><table width="100%"> <tr> <td align="left"><div align="left" id="breadcrumb"><a href="transitions.html"><<Previous</a></div></td> <td align="center"><div align="center" id="breadcrumb"><a href="index.html">Top</a></div></td> <td align="right"><div align="right" id="breadcrumb"><a href="styling.html">Next>></a></div></td> </tr></table><!-- END BREADCRUMB --><!-- START SITECATALYST --><!--stopindex--><script language="JavaScript" src="/share/omniture/s_code_remote.js"></script><!--startindex--><!-- END SITECATALYST --><hr/><!-- BEGIN G9 VARIATION 0 --><!-- (removed) --><!-- END G9 VARIATION 0 --><!-- BEGIN A5 COMPONENT V.0 --><div class="a5" id="a5v0"><span class="footerlinks"><!--<a href="/contact/">Contact</a><a href="/aboutsun/index.html">About Sun</a><a href="/aboutsun/media/index.html">News & Events</a><a href="/corp_emp/">Employment</a><a href="/sitemap/">Site Map</a><a href="/privacy/">Privacy</a><a href="/share/text/termsofuse.html">Terms of Use</a><a href="/suntrademarks/">Trademarks</a>--><span class="footercopy">Copyright © <span id="copyDate" class="cssDate">2008</span> Sun Microsystems, Inc.</span></span></div><!-- END A5 COMPONENT V.0 --></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
增大字号Ctrl + =
减小字号Ctrl + -
显示快捷键?