javap.1 revision 8813:66c98bd811f1
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Arch: generic
Software: JDK 8
Date: 21 November 2013
SectDesc: Basic Tools
Title: javap.1

javap 1 "21 November 2013" "JDK 8" "Basic Tools"
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NAME
javap - Disassembles one or more class files.
SYNOPSIS
 

javap [options] classfile...

options The command-line options. See Options.

classfile 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.

DESCRIPTION
The \f3javap command disassembles one or more class files. The output depends on the options used. When no options are used, then the \f3javap command prints the package, protected and public fields, and methods of the classes passed to it. The \f3javap command prints its output to \f3stdout.
OPTIONS

-help, --help, -?

Prints a help message for the \f3javap command.

-version

Prints release information.

-l

Prints line and local variable tables.

-public

Shows only public classes and members.

-protected

Shows only protected and public classes and members.

-private, -p

Shows all classes and members.

-Joption

Passes the specified option to the JVM. For example:

 
\f3javap -J-version
 
\f3javap -J-Djava.security.manager -J-Djava.security.policy=MyPolicy MyClassName
 
\f3
For more information about JVM options, see the \f3java(1) command documentation.

-s

Prints internal type signatures.

-sysinfo

Shows system information (path, size, date, MD5 hash) of the class being processed.

-constants

Shows \f3static final constants.

-c

Prints disassembled code, for example, the instructions that comprise the Java bytecodes, for each of the methods in the class.

-verbose

Prints stack size, number of locals and arguments for methods.

-classpath path

Specifies the path the \f3javap command uses to look up classes. Overrides the default or the \f3CLASSPATH environment variable when it is set.

-bootclasspath path

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 and several other JAR files.

-extdir dirs

Overrides the location at which installed extensions are searched for. The default location for extensions is the value of \f3java.ext.dirs.

EXAMPLE
Compile the following \f3DocFooter class:
 
\f3import java.awt.*;
 
\f3import java.applet.*;
 
\f3
 
\f3public class DocFooter extends Applet {
 
\f3 String date;
 
\f3 String email;
 
\f3
 
\f3 public void init() {
 
\f3 resize(500,100);
 
\f3 date = getParameter("LAST_UPDATED");
 
\f3 email = getParameter("EMAIL");
 
\f3 }
 
\f3
 
\f3 public void paint(Graphics g) {
 
\f3 g.drawString(date + " by ",100, 15);
 
\f3 g.drawString(email,290,15);
 
\f3 }
 
\f3}
 
\f3
The output from the \f3javap DocFooter.class command yields the following:
 
\f3Compiled from "DocFooter.java"
 
\f3public class DocFooter extends java.applet.Applet {
 
\f3 java.lang.String date;
 
\f3 java.lang.String email;
 
\f3 public DocFooter();
 
\f3 public void init();
 
\f3 public void paint(java.awt.Graphics);
 
\f3}
 
\f3
The output from \f3javap -c DocFooter.class command yields the following:
 
\f3Compiled from "DocFooter.java"
 
\f3public class DocFooter extends java.applet.Applet {
 
\f3 java.lang.String date;
 
\f3 java.lang.String email;
 
\f3
 
\f3 public DocFooter();
 
\f3 Code:
 
\f3 0: aload_0 
 
\f3 1: invokespecial #1 // Method
 
\f3java/applet/Applet."<init>":()V
 
\f3 4: return 
 
\f3
 
\f3 public void init();
 
\f3 Code:
 
\f3 0: aload_0 
 
\f3 1: sipush 500
 
\f3 4: bipush 100
 
\f3 6: invokevirtual #2 // Method resize:(II)V
 
\f3 9: aload_0 
 
\f3 10: aload_0 
 
\f3 11: ldc #3 // String LAST_UPDATED
 
\f3 13: invokevirtual #4 // Method
 
\f3 getParameter:(Ljava/lang/String;)Ljava/lang/String;
 
\f3 16: putfield #5 // Field date:Ljava/lang/String;
 
\f3 19: aload_0 
 
\f3 20: aload_0 
 
\f3 21: ldc #6 // String EMAIL
 
\f3 23: invokevirtual #4 // Method
 
\f3 getParameter:(Ljava/lang/String;)Ljava/lang/String;
 
\f3 26: putfield #7 // Field email:Ljava/lang/String;
 
\f3 29: return 
 
\f3
 
\f3 public void paint(java.awt.Graphics);
 
\f3 Code:
 
\f3 0: aload_1 
 
\f3 1: new #8 // class java/lang/StringBuilder
 
\f3 4: dup 
 
\f3 5: invokespecial #9 // Method
 
\f3 java/lang/StringBuilder."<init>":()V
 
\f3 8: aload_0 
 
\f3 9: getfield #5 // Field date:Ljava/lang/String;
 
\f3 12: invokevirtual #10 // Method
 
\f3 java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
 
\f3 15: ldc #11 // String by 
 
\f3 17: invokevirtual #10 // Method
 
\f3 java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
 
\f3 20: invokevirtual #12 // Method
 
\f3 java/lang/StringBuilder.toString:()Ljava/lang/String;
 
\f3 23: bipush 100
 
\f3 25: bipush 15
 
\f3 27: invokevirtual #13 // Method
 
\f3 java/awt/Graphics.drawString:(Ljava/lang/String;II)V
 
\f3 30: aload_1 
 
\f3 31: aload_0 
 
\f3 32: getfield #7 // Field email:Ljava/lang/String;
 
\f3 35: sipush 290
 
\f3 38: bipush 15
 
\f3 40: invokevirtual #13 // Method
 
\f3java/awt/Graphics.drawString:(Ljava/lang/String;II)V
 
\f3 43: return 
 
\f3}
 
\f3
SEE ALSO

0.2i javac(1)

0.2i java(1)

0.2i jdb(1)

0.2i javah(1)

0.2i javadoc(1)

'pl 8.5i 'bp