Using javap.exe?

Question

There's a source file Disassemble.java, the codes is following,
package test;
interface IA {
  public void print(String str);
class IAImpl implements IA {
  public IAImpl() {
    System.out.println("class A");
  public void print(String str) {
    System.out.println(str);
public class Disassemble {
  public static void main(String[] args) {
    IA a = new IAImpl();
    a.print("class Disassemble");
}Run command javap -c test.Disassemble, the output is
Compiled from "Disassemble.java"
public class test.Disassemble extends java.lang.Object{
public test.Disassemble();
  Code:
   0:  aload_0
   1:  invokespecial  #8; //Method java/lang/Object."<init>":()V
   4:  return
public static void main(java.lang.String[]);
  Code:
   0:  new  #16; //class test/IAImpl
   3:  dup
   4:  invokespecial  #18; //Method test/IAImpl."<init>":()V
   7:  astore_1
   8:  aload_1
   9:  ldc  #19; //String class Disassemble
   11:  invokeinterface  #21,  2; //InterfaceMethod test/IA.print:(Ljava/lang/String;)V
   16:  return
}What's mean of aload_0, astore_1, dup, invokespecial, ldc, and so on?
How can I read the statements?
a cup of Java, cheers!
Sha Jiang

Answer 1

You must buy, or download, the Java Virtual Machine Specification.
http://java.sun.com/docs/books/vmspec/index.html