@xrb’s Blog

Java Quiz of the Day II

What gives:

Integer a = 100, b = 100;
Integer c = 200, d = 200;
System.out.println( (a == b) == (c == d) ); // A

Response: counter intuitively, the program prints ‘false’ out. Integer in Java is a non-native class, where ‘==’ means…

Java Quiz of the Day

What gives

Double a = null;
Double b = a == null ? a : 1.0;

Response: as strange as it can seem at first look, b is not equal to null after the second statement, but the code produces a NullPointerException.

Sparse Files — Commands Overview

I was just checking which commands are supporting sparse files. I post hereafter a short overview of what I found out (working on Linux).

• Create a sparse file of 20 GiB: 
   dd if=/dev/zero of=foo bs=1 count=1 seek=20G

How to Know if a File on Linux is Sparse?

A sparse file is a file which does not take more space on disk than needed. Such a file is usually used to store a partition image on disk, for instance with a virtualization solution like Xen.

NFS Automount with Snow Leopard

Before upgrading to Snow Leopard, I was using the NFS automount capability of Mac OS X. It was a handy way for my laptop to connect to my home NAS server (a linux box running Ubuntu).

Time Machine: Handy but Bitchy!

I have been spending the last couple of days of my spare time performing a simple operation with my mac, yet slightly more complicated than expected: merge the two partitions of my hard drive into one. This was necessary since I did a mapping, quite usual on Linux, where my…

The Geekiest Hello World

Folks, I think that I have found (one of) the geekiest hello world out there. Implemented in Groovy using the dynamic interception of method calls. Here it goes:

class Hello {
  Object invokeMethod(String name, Object arguments) {
    System.out.println "hello…