📄 appb.htm
字号:
<HTML><HEAD><TITLE>developer.com - Reference</TITLE><META NAME="Author" CONTENT="developer.com"><META NAME="Keywords" CONTENT="javascript, ActiveX, VRML, Push, channel,push channel, applet, directory, news, community, developer, internet,intranet, java, java applet, J++, javabeans, java products, tools, javatools, JDK, java development kit, java development environment, JIT,JavaPlan, enterprise tools, JVM, Java Virtual Machine, Java resources, API,browser, java documentation, CDF, Common Desktop Format, RDF, ResourceDescription Framework, Netcaster, Netcast, Castanet, meta-language, metadata,solaris, Solaris, SUN, CGI, Perl, Oracle, database, network, Netscape API,Apache, apache, SSL, mSQL, Netscape, Fasttrack, FastTrack,industry standard, ActiveX bridge, web, internet, site, sitedesign, microsoft, active server pages, asp, iis, nt, win95, 95, html, cgi,frontpage, business, corporate, vbscript, javascript, activex, isapi,database, access, sql, server, www, 3.0, 3.01, 3.02, 3.03, 3.04, 4.0,4.0b2, 4.01, 4.03, 4.04, connection, online, commerce, publisher,publishing, publish, webmaster, dynamic html, dhtml, windows 98, netscape,netscape software, shareware, magazines, jobs, japan, free, freeware, freestuff"><META NAME="description" CONTENT="Developer.com is the leading onlineservice for developers. It includes Gamelan, the official directory for Java, as wellas news, information, tutorials, and directories for other Internet technologiesincluding ActiveX, JavaScript, perl, VRML, Java Beans, push technologies, andother Internet and intranet technologies. Developer.com is also the home ofDeveloper Direct, the Professional Developer's Store, where developers canpurchase and download thousands of Web, authoring and other developmentproducts at some of today's lowest prices."><META NAME="distribution" CONTENT="global"><META NAME="resource-type" CONTENT="document"><META NAME="language" CONTENT="en"></HEAD><BODY BACKGROUND="/images/curve_r-wide.gif" BGCOLOR="#FFFFFF" TEXT="#000000" LINK="#DD0000" VLINK="#999999" ALINK="#FF0000"><TABLE><TR><TD VALIGN=TOP WIDTH=120><A HREF="/" ><IMG SRC="/images/masthead_r.gif" WIDTH="100" HEIGHT="78" BORDER="0"ALT="Developer.com Logo"></a></TD><TD><a target="resource window" href="http://adserver.developer.com/cgi-bin/accipiter/adclick.exe/AREA=DCBAN.REF/DT=null"><img src="http://adserver.developer.com/cgi-bin/accipiter/adserver.exe/AREA=DCBAN.REF/DT=null" HEIGHT="60" WIDTH="468" ALT="Click here to support our advertisers"><BR><CENTER>Click here to support our advertisers</CENTER></a></TD></TR></TABLE><!--outer table--><TABLE><!--outer table--><TR><!--outer table--><TD VALIGN="TOP"><!--navbar info --><table><tr><td><A HREF="http://www.developerdirect.com/" ><IMG SRC="/images/button_s.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><b>SHOPPING</b></font></a></td></tr><tr><td><A HREF="/community/jobs/c_jobs.html"><IMG SRC="/images/button_d.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><B>JOB BANK</B></font></a></td></tr><tr><td><A HREF="http://www.classifieds2000.com/cgi-cls/display.exe?Developer+computer+searchcomputercategories"><IMG SRC="/images/button_d.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><B>CLASSIFIEDS</B></font></a></td></tr><tr><td><A HREF="/directories/directories.html"><IMG SRC="/images/button_d.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><B>DIRECTORIES</B></font></a></td></tr><tr><td><A HREF="/reference/"><IMG SRC="/images/button_r.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><B>REFERENCE</B></font></a><br><a href="/reference/r_library.html"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000">Online Library</a></font></td></tr><tr><td><A HREF="/classroom/"><IMG SRC="/images/button_r.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><B>LEARNING CENTER</B></font></a></td></tr><tr><td><A HREF="/journal/"><IMG SRC="/images/button_n.gif" width="15" height="11" BORDER="0"><B><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000">JOURNAL</font></B></a></td></tr><tr><td><A HREF="/news/"><IMG SRC="/images/button_d.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><b>NEWS CENTRAL</b></font></a></td></tr><tr><td><A HREF="/downloads/"><IMG SRC="/images/button_d.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><b>DOWNLOADS</b></font></a></td></tr><tr><td><A HREF="/community/" ><IMG SRC="/images/button_c.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><B>COMMUNITY</B></font></a></td></tr><tr><td><A HREF="/calendar/"><IMG SRC="/images/button_d.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><b>CALENDAR</b></font></a></td></tr><tr><td><A HREF="/about/"><IMG SRC="/images/button_a.gif" width="15" height="11" BORDER="0"><FONT FACE="Arial, Helvetica" SIZE="-1" color="#000000"><b>ABOUT US</b></a></font></td></tr></table><table><tr><td><form action="/subscribe/list.cgi" method=post ><img src="/images/rule.gif" width="100" height="2"><br><B><FONT FACE="Arial, Helvetica" SIZE="-1">Journal:</b></font><br><input name='email' value='your e-mail' size="11"><input type='hidden' name='state' value='Subscribe'></td></tr><tr><td><input type='submit' value='Subscribe'><br><font size="-1">Get the weekly email highlights from the most popular journal for developers!<br><a href="http://www.developer.com/subscribe.html">Current issue</a><img src="/images/rule.gif" width="100" height="2"><input type='hidden' name='name' value='New Subscriber'></FORM></td></tr></table><!--/navbar--><font size="-1"><A HREF="http://www.developer.com">developer.com</a><BR><A HREF="http://www.developerdirect.com">developerdirect.com</a><BR><A HREF="http://www.htmlgoodies.com">htmlgoodies.com</a><BR><A HREF="http://www.javagoodies.com">javagoodies.com</a><br><A HREF="http://www.jars.com">jars.com</a><BR><a href="http://www.intranetjournal.com">intranetjournal.com</a><br><a href="http://www.javascripts.com">javascripts.com</a><br></font><!--outer table--></TD><!--outer table--><TD VALIGN="TOP"><BLOCKQUOTE><P><img src="/images/header_r.gif" width="440" height="50"><P><MAP NAME ="header_r2.gif.map"><AREA SHAPE ="RECT" HREF ="/reference/author.html" COORDS ="361,0,440,29"><AREA SHAPE ="RECT" HREF ="/reference/basic.html" COORDS ="254,0,360,29"><AREA SHAPE ="RECT" HREF ="/reference/help.html" COORDS ="183,0,251,29"><AREA SHAPE ="RECT" HREF ="/reference/cool.html" COORDS ="100,0,181,29"><AREA SHAPE ="RECT" HREF ="/reference/mybook.html" COORDS ="0,0,100,29"></MAP><MAP NAME ="header_r1.gif.map"><AREA SHAPE ="RECT" HREF ="/reference/personalize.html" COORDS ="339,0,439,29"></MAP><p><font face="Arial,Helvetica" size="-1" color="#006666"><A HREF="/reference/r_library.html"><B>All Categories</A> :</B><b><A HREF="/reference/r_java.html">Java</A></b></font><p> <META NAME="GENERATOR" CONTENT="Mozilla/3.0b5aGold (WinNT; I) [Netscape]"><H1><FONT COLOR=#FF0000>Appendix B </FONT></H1><H1><B><FONT SIZE=5 COLOR=#FF0000>Language Grammar</FONT></B></H1><P><HR WIDTH="100%"></P><P>This appendix provides a commented Java grammar. A <I>grammar</I>is a series of rules that have the following form:<BLOCKQUOTE><TT>nonterminal = meta-expression ;</TT></BLOCKQUOTE><P>Any quoted symbols (such as "0") indicate a literalsymbol or keyword. The comments should help you understand themore formal grammar.<P>Meta-expressions use the following additional notation:<UL><LI><TT>(<I>some expression</I>)</TT>for grouping<LI><TT>postfix?</TT> for 0 or 1 occurrencesrequired<LI><TT>postfix+</TT> for 1 or moreoccurrences required<LI><TT>postfix*</TT> for 0 or moreoccurrences required<LI><TT>:|</TT> for alteration (either-or)</UL><P>The grammar is not exactly BNF (Backus-Naur Form), but it getsthe job done. I prefer a more formal notation, but it's Sun'sprerogative to choose the grammar specification format.<BR><P><CENTER><TABLE BORDERCOLOR=#000000 BORDER=1 WIDTH=80%><TR VALIGN=TOP><TD><B>Note</B></TD></TR><TR VALIGN=TOP><TD><BLOCKQUOTE>The following terminal symbols are undefined: DocComment, Identifier, Number, String, and Character. "Undefined" specifically means that the terminal symbols are referenced in a right-hand rule, but never defined as a left-hand quantity.</BLOCKQUOTE></TD></TR></TABLE></CENTER><P><BLOCKQUOTE><TT>CompilationUnit =<BR> PackageStatement? ImportStatement* TypeDeclaration*<BR>;</TT></BLOCKQUOTE><P>A compilation unit is the outermost definition in this grammar.An application or applet can be made up of multiple compilationunits. The stars after the last two names indicate zero or moreoccurrences, and the question mark indicates zero or one occurrence.<BLOCKQUOTE><TT>PackageStatement =<BR> 'package' PackageName ';'<BR>;<BR>ImportStatement =<BR> 'import' PackageName '.' '*' ';'<BR>| 'import' ( ClassName | InterfaceName ) ';'<BR>;<BR>TypeDeclaration =<BR> ClassDeclaration<BR>| InterfaceDeclaration<BR>| ';'<BR>;</TT></BLOCKQUOTE><P>This rule forces all fields and methods to appear within a class.In C, this rule also contains variable and function definitionoptions:<BLOCKQUOTE><TT>ClassDeclaration =<BR> Modifier* 'class' Identifier<BR> ('extends' ClassName)?<BR> ('implements' InterfaceName (',' InterfaceName)*)?<BR> '{' FieldDeclaration* '}'<BR>;</TT></BLOCKQUOTE><P>This rule looks a little confusing because of its optional notation.A class declaration may have one or more modifiers before thekeyword <TT>class</TT>. The extendsclause and interface clause are optional. If the interface clauseis present, there may be multiple comma-separated interface names.The class must be followed by braces, but there do not have tobe any fields defined within them.<BLOCKQUOTE><TT>InterfaceDeclaration =<BR> Modifier* 'interface' Identifier<BR>⌨️ 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 + -