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javap(1) Basic Tools javap(1)
NAME
javap - Disassembles one or more class files.
SYNOPSIS
javap [options] classfile...
options
The command-line options. See Options.
classfile
One or more classes separated by spaces to be processed for annotations such as
DocFooter.class. You can specify a class that can be found in the class path, by its
file name or with a URL such as file:///home/user/myproject/src/DocFooter.class.
DESCRIPTION
The javap command disassembles one or more class files. The output depends on the options
used. When no options are used, then the javap command prints the package, protected and
public fields, and methods of the classes passed to it. The javap command prints its
output to stdout.
OPTIONS
-help
--help
-?
Prints a help message for the javap command.
-version
Prints release information.
-l
Prints line and local variable tables.
-public
Shows only public classes and members.
-protected
Shows only protected and public classes and members.
-private
-p
Shows all classes and members.
-Joption
Passes the specified option to the JVM. For example:
javap -J-version
javap -J-Djava.security.manager -J-Djava.security.policy=MyPolicy MyClassName
For more information about JVM options, see the command documentation.
-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 disassembled code, for example, the instructions that comprise the Java
bytecodes, for each of the methods in the class.
-verbose
Prints stack size, number of locals and arguments for methods.
-classpath path
Specifies the path the javap command uses to look up classes. Overrides the default or
the CLASSPATH environment variable when it is set.
-bootclasspath path
Specifies the path from which to load bootstrap classes. By default, the bootstrap
classes are the classes that implement the core Java platform located in
jre/lib/rt.jar and several other JAR files.
-extdir dirs
Overrides the location at which installed extensions are searched for. The default
location for extensions is the value of java.ext.dirs.
EXAMPLE
Compile the following DocFooter class:
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 the javap DocFooter.class command yields the following:
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 command yields the following:
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
}
SEE ALSO
o java(1)
o javac(1)
o javadoc(1)
o javah(1)
o jdb(1)
o jdeps(1)
JDK 8 8 August 2014 javap(1)
Generated by $Id: phpMan.php,v 4.55 2007/09/05 04:42:51 chedong Exp $ Author: Che Dong
On Apache
Under GNU General Public License
2024-12-12 16:59 @13.58.137.54 CrawledBy Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)