javap(1)javap(1)Namejavap - The Java Class File Disassembler
Disassembles class files.
SYNOPSISjavap [ options ] classes
DESCRIPTION
The javap command disassembles one or more class files. 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.
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, /home/user/myproject/src/DocFooter.class), or with a URL
(for example, file:///home/user/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."<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
}
OPTIONS-help --help -?
Prints out help message for javap.
-version
Prints out version information.
-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.
-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.
-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 com‐
prise 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.
-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.
SEE ALSOjavac(1), java(1), jdb(1), javah(1), javadoc(1)
16 Mar 2012 javap(1)
