The Java Class File Disassembler (original) (raw)

Disassembles class files.

SYNOPSIS

javap [ options ] classes

DESCRIPTION

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

options

Command-line options.

classes

List of one or more classes (separated by spaces) to be processed for annotations (such as DocFooter.class). You may specify a class that can be found in the class path, by its file name (for example, C:\myproject\src\DocFooter.class), or with a URL (for example, file:///C:/myproject/src/DocFooter.class).

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.class 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.class yields:

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."":()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."":()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
}

OPTIONS

-help --help -?

Prints out help message for javap.

-l

Prints out line and local variable tables.

-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 -p

Shows all classes and members.

-J_flag_

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.

-sysinfo

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

-constants

Shows static final constants.

-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 andargs 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.

-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 ofjava.ext.dirs.

The Java Class File Disassembler (original) (raw)

SYNOPSIS

DESCRIPTION

OPTIONS

SEE ALSO