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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