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# javap - The Java Class File Disassembler

> Disassembles class files.

## SYNOPSIS

>     javap [ options ] class. . .

## DESCRIPTION

> The javap command disassembles a class file. Its output depends on the options used. If no options are used, javap prints out the package, protected, and public fields and methods of the classes passed to it. javap prints its output to stdout. For example, compile the following class declaration:

> >     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 javap DocFooter yields:

> >     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 yields:

> >     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);
> >     }

> >     Method DocFooter()
> >        0 aload_0
> >        1 invokespecial #1 <Method java.applet.Applet()>
> >        4 return

> >     Method void init()
> >        0 aload_0
> >        1 sipush 500
> >        4 bipush 100
> >        6 invokevirtual #2 <Method void resize(int, int)>
> >        9 aload_0
> >       10 aload_0
> >       11 ldc #3 <String "LAST_UPDATED">
> >       13 invokevirtual #4 <Method java.lang.String getParameter(java.lang.String)>
> >       16 putfield #5 <Field java.lang.String date>
> >       19 aload_0
> >       20 aload_0
> >       21 ldc #6 <String "EMAIL">
> >       23 invokevirtual #4 <Method java.lang.String getParameter(java.lang.String)>
> >       26 putfield #7 <Field java.lang.String email>
> >       29 return

> >     Method void paint(java.awt.Graphics)
> >        0 aload_1
> >        1 new #8 <Class java.lang.StringBuffer>
> >        4 dup
> >        5 invokespecial #9 <Method java.lang.StringBuffer()>
> >        8 aload_0
> >        9 getfield #5 <Field java.lang.String date>
> >       12 invokevirtual #10 <Method java.lang.StringBuffer append(java.lang.String)>
> >       15 ldc #11 <String " by ">
> >       17 invokevirtual #10 <Method java.lang.StringBuffer append(java.lang.String)>
> >       20 invokevirtual #12 <Method java.lang.String toString()>
> >       23 bipush 100
> >       25 bipush 15
> >       27 invokevirtual #13 <Method void drawString(java.lang.String, int, int)>
> >       30 aload_1
> >       31 aload_0
> >       32 getfield #7 <Field java.lang.String email>
> >       35 sipush 290
> >       38 bipush 15
> >       40 invokevirtual #13 <Method void drawString(java.lang.String, int, int)>
> >       43 return

## OPTIONS

> -help
>   Prints out help message for javap.
> -l
>   Prints out line and local variable tables.
> -b
>   Ensures backward compatibility with javap in JDK 1.1.
> -public
>   Shows only public classes and members.
> -protected
>   Shows only protected and public classes and members.
> -package
>   Shows only package, protected, and public classes and members. This is the default.
> -private
>   Shows all classes and members.
> -Jflag
>   Pass flag directly to the runtime system. Some examples:

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

> -s
>   Prints internal type signatures.
> -c
>   Prints out disassembled code, i.e., the instructions that comprise the Java bytecodes, for each of the methods in the class. These are documented in the Java Virtual Machine Specification.
> -verbose
>   Prints stack size, number of `locals` and `args` for methods.
> -classpath path
>   Specifies the path javap uses to look up classes. Overrides the default or the CLASSPATH environment variable if it is set. Directories are separated by colons. Thus the general format for path is:

>          .:<your_path>

>   For example:

>       .:/home/avh/classes:/usr/local/java/classes

> -bootclasspath path
>   Specifies path from which to load bootstrap classes. By default, the bootstrap classes are the classes implementing the core Java platform located in `jre/lib/rt.jar` and several other jar files.
> -extdirs dirs
>   Overrides location at which installed extensions are searched for. The default location for extensions is the value of `java.ext.dirs`.

## ENVIRONMENT VARIABLES

> CLASSPATH
>   Used to provide the system a path to user-defined classes. Directories are separated by colons, for example, For example:

>   >     .:/home/avh/classes:/usr/local/java/classes

## SEE ALSO

> javac, java, jdb, javah, javadoc

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