man/man1/javap.1

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 Title: javap
 Language: English
 Date: 8 August 2014
 SectDesc: Basic Tools
 Software: JDK 8
 Arch: generic
 Part Number: E38207-03

 "javap" "1" "8 August 2014" "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
file:///home/user/myproject/src/DocFooter.class.

 "DESCRIPTION"

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

-help

--help

-?

Prints a help message for the
javap
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:

.\}
javap -J-version
javap -J-Djava.security.manager -J-Djava.security.policy=MyPolicy MyClassName


.\}
For more information about JVM options, see the command documentation.


-s

Prints internal type signatures.


-sysinfo

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


-constants

Shows
static 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
javap
command uses to look up classes. Overrides the default or the
CLASSPATH
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
jre/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
java.ext.dirs.

 "EXAMPLE"

Compile the following
DocFooter
class:

.\}
import java.awt.*;
import java.applet.*;

public class DocFooter extends Applet {
 String date;
 String email;

 public void init() {
 resize(500,100);
 date = getParameter("LAST_UPDATED");
 email = getParameter("EMAIL");
 }

 public void paint(Graphics g) {
 g.drawString(date + " by ",100, 15);
 g.drawString(email,290,15);
 }
}


.\}

The output from the
javap DocFooter.class
command yields the following:

.\}
Compiled from "DocFooter.java"
public class DocFooter extends java.applet.Applet {
 java.lang.String date;
 java.lang.String email;
 public DocFooter();
 public void init();
 public void paint(java.awt.Graphics);
}


.\}

The output from
javap -c DocFooter.class
command yields the following:

.\}
Compiled from "DocFooter.java"
public class DocFooter extends java.applet.Applet {
 java.lang.String date;
 java.lang.String email;

 public DocFooter();
 Code:
 0: aload_0
 1: invokespecial #1 // Method
java/applet/Applet."<init>":()V
 4: return

 public void init();
 Code:
 0: aload_0
 1: sipush 500
 4: bipush 100
 6: invokevirtual #2 // Method resize:(II)V
 9: aload_0
 10: aload_0
 11: ldc #3 // String LAST_UPDATED
 13: invokevirtual #4 // Method
 getParameter:(Ljava/lang/String;)Ljava/lang/String;
 16: putfield #5 // Field date:Ljava/lang/String;
 19: aload_0
 20: aload_0
 21: ldc #6 // String EMAIL
 23: invokevirtual #4 // Method
 getParameter:(Ljava/lang/String;)Ljava/lang/String;
 26: putfield #7 // Field email:Ljava/lang/String;
 29: return

 public void paint(java.awt.Graphics);
 Code:
 0: aload_1
 1: new #8 // class java/lang/StringBuilder
 4: dup
 5: invokespecial #9 // Method
 java/lang/StringBuilder."<init>":()V
 8: aload_0
 9: getfield #5 // Field date:Ljava/lang/String;
 12: invokevirtual #10 // Method
 java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
 15: ldc #11 // String by
 17: invokevirtual #10 // Method
 java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
 20: invokevirtual #12 // Method
 java/lang/StringBuilder.toString:()Ljava/lang/String;
 23: bipush 100
 25: bipush 15
 27: invokevirtual #13 // Method
 java/awt/Graphics.drawString:(Ljava/lang/String;II)V
 30: aload_1
 31: aload_0
 32: getfield #7 // Field email:Ljava/lang/String;
 35: sipush 290
 38: bipush 15
 40: invokevirtual #13 // Method
java/awt/Graphics.drawString:(Ljava/lang/String;II)V
 43: return
}


.\}
 "SEE ALSO"

\h'-04'\(bu\h'+03'\c
.\}
 \(bu 2.3
.\}
java(1)


\h'-04'\(bu\h'+03'\c
.\}
 \(bu 2.3
.\}
javac(1)


\h'-04'\(bu\h'+03'\c
.\}
 \(bu 2.3
.\}
javadoc(1)


\h'-04'\(bu\h'+03'\c
.\}
 \(bu 2.3
.\}
javah(1)


\h'-04'\(bu\h'+03'\c
.\}
 \(bu 2.3
.\}
jdb(1)


\h'-04'\(bu\h'+03'\c
.\}
 \(bu 2.3
.\}
jdeps(1)


'pl 8.5i
'bp