javap(1)javap(1)NAMEjavap - The Java Class File Disassembler
Disassembles class files.
SYNOPSISjavap [ 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 <Method java.applet.Applet()>
4 return
Method void init()
0 aload_0
1 sipush 500
4 bipush 100
6 invokevirtual #2 <Method void resize(int, int)>
9 aload_0
10 aload_0
11 ldc #3 <String "LAST_UPDATED">
13 invokevirtual #4 <Method java.lang.String getParameter(java.lang.String)>
16 putfield #5 <Field java.lang.String date>
19 aload_0
20 aload_0
21 ldc #6 <String "EMAIL">
23 invokevirtual #4 <Method java.lang.String getParameter(java.lang.String)>
26 putfield #7 <Field java.lang.String email>
29 return
Method void paint(java.awt.Graphics)
0 aload_1
1 new #8 <Class java.lang.StringBuffer>
4 dup
5 invokespecial #9 <Method java.lang.StringBuffer()>
8 aload_0
9 getfield #5 <Field java.lang.String date>
12 invokevirtual #10 <Method java.lang.StringBuffer append(java.lang.String)>
15 ldc #11 <String " by ">
17 invokevirtual #10 <Method java.lang.StringBuffer append(java.lang.String)>
20 invokevirtual #12 <Method java.lang.String toString()>
23 bipush 100
25 bipush 15
27 invokevirtual #13 <Method void drawString(java.lang.String, int, int)>
30 aload_1
31 aload_0
32 getfield #7 <Field java.lang.String email>
35 sipush 290
38 bipush 15
40 invokevirtual #13 <Method void drawString(java.lang.String, int, int)>
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:
.:<your_path>
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)