Re: Objects in java

From:

"John B. Matthews" <nospam@nospam.invalid>

Newsgroups:

comp.lang.java.programmer

Date:

Sat, 04 Jul 2009 08:34:39 -0400

Message-ID:

<nospam-62CB75.08343904072009@news.aioe.org>

In article
<aa027c04-f084-4ddd-9a8f-49137e84e223@2g2000prl.googlegroups.com>,
Prasoon <prasoonthegreat@gmail.com> wrote:

Suppose when we write

int x=5;

The memory is allocated for 'x' at compile time by the compiler or at
the run time by the [JVM]?

Let's see:

$ cat Allocate.java ; javac Allocate.java ; javap -c Allocate
public class Allocate {
    public static void main(String[] args) {
        int x = 5;
    }
}
Compiled from "Allocate.java"
public class Allocate extends java.lang.Object{
public Allocate();
  Code:
   0: aload_0
   1: invokespecial #1; //Method java/lang/Object."<init>":()V
   4: return

public static void main(java.lang.String[]);
  Code:
   0: iconst_5
   1: istore_1
   2: return

}

I don't see any memory allocated "for 'x' at compile time." At run time,
the literal integer constant 5, whose size was known at compile time, is
stored in the 1st local variable of method main(). See section 3.11:

<http://java.sun.com/docs/books/jvms/second_edition/html/VMSpecTOC.doc.html>

--
John B. Matthews
     at gmail dot com
<http://sites.google.com/site/drjohnbmatthews>