javap

javap(1)                                                              javap(1)



NAME
       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 
             4 return

          Method void init()
             0 aload_0
             1 sipush 500
             4 bipush 100
             6 invokevirtual #2 
             9 aload_0
            10 aload_0
            11 ldc #3 
            13 invokevirtual #4 
            16 putfield #5 
            19 aload_0
            20 aload_0
            21 ldc #6 
            23 invokevirtual #4 
            26 putfield #7 
            29 return

          Method void paint(java.awt.Graphics)
             0 aload_1
             1 new #8 
             4 dup
             5 invokespecial #9 
             8 aload_0
             9 getfield #5 
            12 invokevirtual #10 
            15 ldc #11 
            17 invokevirtual #10 
            20 invokevirtual #12 
            23 bipush 100
            25 bipush 15
            27 invokevirtual #13 
            30 aload_1
            31 aload_0
            32 getfield #7 
            35 sipush 290
            38 bipush 15
            40 invokevirtual #13 
            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 @
          http://java.sun.com/docs/books/vmspec/.

       -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. Directo‐
          ries are separated by colons. Thus the general format for path is:
             .:
          For example:

       -bootclasspath path
          Specifies path from which to load bootstrap classes. By default, the
          bootstrap classes are the classes implementing the core Java plat‐
          form 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. Directo‐
          ries are separated by colons, for example, For example:


SEE ALSO
       javac, java, jdb, javah, javadoc

                                  05 Aug 2006                         javap(1)