8058243: Reduce size of bytecode for large switch statements
Reviewed-by: jjg, vromero
'\" t
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.\" or visit www.oracle.com if you need additional information or have any
.\" questions.
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.\" Arch: generic
.\" Software: JDK 8
.\" Date: 21 November 2013
.\" SectDesc: Basic Tools
.\" Title: javap.1
.\"
.if n .pl 99999
.TH javap 1 "21 November 2013" "JDK 8" "Basic Tools"
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.\" * MAIN CONTENT STARTS HERE *
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.SH NAME
javap \- Disassembles one or more class files\&.
.SH SYNOPSIS
.sp
.nf
\fBjavap\fR [\fIoptions\fR] \fIclassfile\fR\&.\&.\&.
.fi
.sp
.TP
\fIoptions\fR
The command-line options\&. See Options\&.
.TP
\fIclassfile\fR
One or more classes separated by spaces to be processed for annotations such as DocFooter\&.class\&. You can specify a class that can be found in the class path, by its file name or with a URL such as \f3file:///home/user/myproject/src/DocFooter\&.class\fR\&.
.SH DESCRIPTION
The \f3javap\fR command disassembles one or more class files\&. The output depends on the options used\&. When no options are used, then the \f3javap\fR command prints the package, protected and public fields, and methods of the classes passed to it\&. The \f3javap\fR command prints its output to \f3stdout\fR\&.
.SH OPTIONS
.TP
-help, --help, -?
.br
Prints a help message for the \f3javap\fR command\&.
.TP
-version
.br
Prints release information\&.
.TP
-l
.br
Prints line and local variable tables\&.
.TP
-public
.br
Shows only public classes and members\&.
.TP
-protected
.br
Shows only protected and public classes and members\&.
.TP
-private, -p
.br
Shows all classes and members\&.
.TP
-J\fIoption\fR
.br
Passes the specified option to the JVM\&. For example:
.sp
.nf
\f3javap \-J\-version\fP
.fi
.nf
\f3javap \-J\-Djava\&.security\&.manager \-J\-Djava\&.security\&.policy=MyPolicy MyClassName\fP
.fi
.nf
\f3\fP
.fi
.sp
For more information about JVM options, see the \f3java(1)\fR command documentation\&.
.TP
-s
.br
Prints internal type signatures\&.
.TP
-sysinfo
.br
Shows system information (path, size, date, MD5 hash) of the class being processed\&.
.TP
-constants
.br
Shows \f3static final\fR constants\&.
.TP
-c
.br
Prints disassembled code, for example, the instructions that comprise the Java bytecodes, for each of the methods in the class\&.
.TP
-verbose
.br
Prints stack size, number of locals and arguments for methods\&.
.TP
-classpath \fIpath\fR
.br
Specifies the path the \f3javap\fR command uses to look up classes\&. Overrides the default or the \f3CLASSPATH\fR environment variable when it is set\&.
.TP
-bootclasspath \fIpath\fR
.br
Specifies the path from which to load bootstrap classes\&. By default, the bootstrap classes are the classes that implement the core Java platform located in \f3jre/lib/rt\&.jar\fR and several other JAR files\&.
.TP
-extdir \fIdirs\fR
.br
Overrides the location at which installed extensions are searched for\&. The default location for extensions is the value of \f3java\&.ext\&.dirs\fR\&.
.SH EXAMPLE
Compile the following \f3DocFooter\fR class:
.sp
.nf
\f3import java\&.awt\&.*;\fP
.fi
.nf
\f3import java\&.applet\&.*;\fP
.fi
.nf
\f3\fP
.fi
.nf
\f3public class DocFooter extends Applet {\fP
.fi
.nf
\f3 String date;\fP
.fi
.nf
\f3 String email;\fP
.fi
.nf
\f3\fP
.fi
.nf
\f3 public void init() {\fP
.fi
.nf
\f3 resize(500,100);\fP
.fi
.nf
\f3 date = getParameter("LAST_UPDATED");\fP
.fi
.nf
\f3 email = getParameter("EMAIL");\fP
.fi
.nf
\f3 }\fP
.fi
.nf
\f3\fP
.fi
.nf
\f3 public void paint(Graphics g) {\fP
.fi
.nf
\f3 g\&.drawString(date + " by ",100, 15);\fP
.fi
.nf
\f3 g\&.drawString(email,290,15);\fP
.fi
.nf
\f3 }\fP
.fi
.nf
\f3}\fP
.fi
.nf
\f3\fP
.fi
.sp
The output from the \f3javap DocFooter\&.class\fR command yields the following:
.sp
.nf
\f3Compiled from "DocFooter\&.java"\fP
.fi
.nf
\f3public class DocFooter extends java\&.applet\&.Applet {\fP
.fi
.nf
\f3 java\&.lang\&.String date;\fP
.fi
.nf
\f3 java\&.lang\&.String email;\fP
.fi
.nf
\f3 public DocFooter();\fP
.fi
.nf
\f3 public void init();\fP
.fi
.nf
\f3 public void paint(java\&.awt\&.Graphics);\fP
.fi
.nf
\f3}\fP
.fi
.nf
\f3\fP
.fi
.sp
The output from \f3javap -c DocFooter\&.class\fR command yields the following:
.sp
.nf
\f3Compiled from "DocFooter\&.java"\fP
.fi
.nf
\f3public class DocFooter extends java\&.applet\&.Applet {\fP
.fi
.nf
\f3 java\&.lang\&.String date;\fP
.fi
.nf
\f3 java\&.lang\&.String email;\fP
.fi
.nf
\f3\fP
.fi
.nf
\f3 public DocFooter();\fP
.fi
.nf
\f3 Code:\fP
.fi
.nf
\f3 0: aload_0 \fP
.fi
.nf
\f3 1: invokespecial #1 // Method\fP
.fi
.nf
\f3java/applet/Applet\&."<init>":()V\fP
.fi
.nf
\f3 4: return \fP
.fi
.nf
\f3\fP
.fi
.nf
\f3 public void init();\fP
.fi
.nf
\f3 Code:\fP
.fi
.nf
\f3 0: aload_0 \fP
.fi
.nf
\f3 1: sipush 500\fP
.fi
.nf
\f3 4: bipush 100\fP
.fi
.nf
\f3 6: invokevirtual #2 // Method resize:(II)V\fP
.fi
.nf
\f3 9: aload_0 \fP
.fi
.nf
\f3 10: aload_0 \fP
.fi
.nf
\f3 11: ldc #3 // String LAST_UPDATED\fP
.fi
.nf
\f3 13: invokevirtual #4 // Method\fP
.fi
.nf
\f3 getParameter:(Ljava/lang/String;)Ljava/lang/String;\fP
.fi
.nf
\f3 16: putfield #5 // Field date:Ljava/lang/String;\fP
.fi
.nf
\f3 19: aload_0 \fP
.fi
.nf
\f3 20: aload_0 \fP
.fi
.nf
\f3 21: ldc #6 // String EMAIL\fP
.fi
.nf
\f3 23: invokevirtual #4 // Method\fP
.fi
.nf
\f3 getParameter:(Ljava/lang/String;)Ljava/lang/String;\fP
.fi
.nf
\f3 26: putfield #7 // Field email:Ljava/lang/String;\fP
.fi
.nf
\f3 29: return \fP
.fi
.nf
\f3\fP
.fi
.nf
\f3 public void paint(java\&.awt\&.Graphics);\fP
.fi
.nf
\f3 Code:\fP
.fi
.nf
\f3 0: aload_1 \fP
.fi
.nf
\f3 1: new #8 // class java/lang/StringBuilder\fP
.fi
.nf
\f3 4: dup \fP
.fi
.nf
\f3 5: invokespecial #9 // Method\fP
.fi
.nf
\f3 java/lang/StringBuilder\&."<init>":()V\fP
.fi
.nf
\f3 8: aload_0 \fP
.fi
.nf
\f3 9: getfield #5 // Field date:Ljava/lang/String;\fP
.fi
.nf
\f3 12: invokevirtual #10 // Method\fP
.fi
.nf
\f3 java/lang/StringBuilder\&.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;\fP
.fi
.nf
\f3 15: ldc #11 // String by \fP
.fi
.nf
\f3 17: invokevirtual #10 // Method\fP
.fi
.nf
\f3 java/lang/StringBuilder\&.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;\fP
.fi
.nf
\f3 20: invokevirtual #12 // Method\fP
.fi
.nf
\f3 java/lang/StringBuilder\&.toString:()Ljava/lang/String;\fP
.fi
.nf
\f3 23: bipush 100\fP
.fi
.nf
\f3 25: bipush 15\fP
.fi
.nf
\f3 27: invokevirtual #13 // Method\fP
.fi
.nf
\f3 java/awt/Graphics\&.drawString:(Ljava/lang/String;II)V\fP
.fi
.nf
\f3 30: aload_1 \fP
.fi
.nf
\f3 31: aload_0 \fP
.fi
.nf
\f3 32: getfield #7 // Field email:Ljava/lang/String;\fP
.fi
.nf
\f3 35: sipush 290\fP
.fi
.nf
\f3 38: bipush 15\fP
.fi
.nf
\f3 40: invokevirtual #13 // Method\fP
.fi
.nf
\f3java/awt/Graphics\&.drawString:(Ljava/lang/String;II)V\fP
.fi
.nf
\f3 43: return \fP
.fi
.nf
\f3}\fP
.fi
.nf
\f3\fP
.fi
.sp
.SH SEE\ ALSO
.TP 0.2i
\(bu
javac(1)
.TP 0.2i
\(bu
java(1)
.TP 0.2i
\(bu
jdb(1)
.TP 0.2i
\(bu
javah(1)
.TP 0.2i
\(bu
javadoc(1)
.RE
.br
'pl 8.5i
'bp