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Manual Reference Pages  -  JAVAP (1)

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javap - Disassembles one or more class files.



javap [options] classfile...


The command-line options. See Options.


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.


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.



Prints a help message for the javap command.


Prints release information.


Prints line and local variable tables.


Shows only public classes and members.


Shows only protected and public classes and members.


Shows all classes and members.


Passes the specified option to the JVM. For example:

javap -J-version
javap MyClassName

For more information about JVM options, see the command documentation.


Prints internal type signatures.


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


Shows static final constants.


Prints disassembled code, for example, the instructions that comprise the Java bytecodes, for each of the methods in the class.


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.


Compile the following DocFooter class:

import java.awt.*;
import java.applet.*;
public class DocFooter extends Applet {
        String date;
        String email;
        public void init() {
                date = getParameter("LAST_UPDATED");
                email = getParameter("EMAIL");
        public void paint(Graphics g) {
                g.drawString(date + " by ",100, 15);

The output from the javap DocFooter.class command yields the following:

Compiled from ""
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 ""
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 }



o java(1)


o javac(1)


o javadoc(1)


o javah(1)


o jdb(1)


o jdeps(1)

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JDK 8 JAVAP (1) 8 August 2014

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