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 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 void init();
    public void paint(java.awt.Graphics);
    public DocFooter();
}

OPTIONS
-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.

-J flag
Pass flag directly to the runtime system.

-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.

-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
-h
Generate code which can be put into a C language header file.

-verbose
Prints stack size, number of locals and args for methods.

-verify
Performs a partial verification of the class file. Because this option does not perform many portions of a full verification, its use is not recommended. Instead, java -verify should be used to verify class files. The -verify option of javap will be removed in the next release of the JDK.

-version
Prints out the javap version string.

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, CLASSPATH