how to see the <init> instance initialization method ?

[gurpeet singh]

i have read that for each constructor there is instance initialization method whose name is <init> and return type is void. i would like to know is there any way to view those instance initialization methods generated from the source file using any tool/command-line or perhaps through IDE?

[John Jai]

I am not aware of this concept, but can see a <init> and an empty return when I use javap -c option.

Java class:

public class Main {
	Main() {
		System.out.println("Hello there!!!");
	}
}

javap output:

C:\test\main>javap -c Main
Compiled from "Main.java"
public class Main extends java.lang.Object{
Main();
  Code:
   0:   aload_0
   1:   invokespecial   #1; //Method java/lang/Object."<init>":()V
   4:   getstatic       #2; //Field java/lang/System.out:Ljava/io/PrintStream;
   7:   ldc     #3; //String Hello there!!!
   9:   invokevirtual   #4; //Method java/io/PrintStream.println:(Ljava/lang/Str
ing;)V
   12:  return

}

[gurpeet singh]

thanks for the reply John. i read an article on object initialization at http://www.javaworld.com/javaworld/jw-03-1998/jw-03-initialization.html?page=5 . i liked it alot. lets wait for other ranchers if there is any way to view the <init> methods.

[Henry Wong]

Not really adding anything to this discussion -- but just want to mention.... that all of these years of using / debugging with Java (and working with lots of stacktraces), I have never thought that there was an "<init>" method. I just thought that is how the stacktrace code shows that you are in constructor code. Oh well.

Henry

[Matthew Brown]

Henry Wong wrote:
Not really adding anything to this discussion -- but just want to mention.... that all of these years of using / debugging with Java (and working with lots of stacktraces), I have never thought that there was an "<init>" method. I just thought that is how the stacktrace code shows that you are in constructor code. Oh well.

I'd have probably thought the same way, but I was looking something up earlier to today (related to another question here) that made me realise it is real: if you look at
java.lang.Class#getMethod(java.lang.String, java.lang.Class...) you can see that <init> is treated as a special case (i.e. it's a method, but that method will pretend it isn't).

[gurpeet singh]

thanks for the information guys. but if the <init> method is real, which it is then there should be some way to see it ? the original question is still yet to be answered/

[Matthew Brown]

It's real in the byte-code. So the only way to see it is with a byte-code viewer, which is what John showed.