Savio's Notes: Java Book: Effective Java - Chapter 2 - Item 1

The first in a series of notes about the book Effective Java by Joshua Bloch will cover Chapter 2 - Item 1. Some sharp readers would be wondering why not Chapter 1. Those who have read the book will be aware that Chapter 1 is more of an introduction to the book and it also will explain why I didn't make any notes for it. So worry not, you haven't missed anything yet!

Item 1
Use static factories instead of constructors
I never thought of it in these terms, but I had always felt uneasy whenever I used the new operator in code. I always tried to never to use the new operator and have either a third utility class that returned a newly minted instance or have a static method that did the same.

But Joshua Bloch puts it more eloquently and convincingly and here are his reasons:

1. Static factories unlike constructors can have more meaningful names which in turn help code readability
2. Static factories unlike constuctors do need to create a new object every time. They could implement some kind of caching mechanism to enable reuse of instances
   
3. Static factories unlike constuctors can return sub-types of their return types

The book also lists disadvantages of this item as:

1. Classes without public or protected constructors cannot be sub-classed. But he goes on to state that this may be an advantage as it forces the use of composition over inheritance which is further elaborated in Item 14
2. Besides the use of naming conventions there is no way to distinguish a static factory from other static methods in the class

In conclusion the book recommends using static factories unless you are convinced that it dooesn't suit your needs. Alternatively if you are confused go with constructors as they are the norm.

From my part, I will now be trying this pattern more often to put in private constructors and use static factories. Maybe the convention to use would be to have the static factory name as getInstanceUsingXxxx(...)

Savio's Notes: An introduction to a blogging series

I recently got my hands on a copy of Effective Java - Programming Language Guide by Joshua Bloch. I've been meaning to read this book for quite a while now as I've heard nothing but praise from most people I know who have read it. Also, having read Effective C and absolutely loving that book, I'm a little biased because of the title of this book.

So I began reading it and got through the first three chapters and thought to my self: "Hey this is common sense stuff and still there are some common mistakes pointed out too!"

It's always great when someone else (a more famous person than oneself) confirms what one is thinking. Now I'm not trying to say that I've known everything that I've read so far. Quite the contrary I've also learnt a quite a bit of new stuff. Which is exactly why, given my terrible memory I though I should make notes for the same.

Now had I been in the office, I'd have Wiki-ed this. So rather than that, I thought let's start a kind-of series on my blog called Savio's Notes that will track these notes of mine on this and various topics.

As the title of the series suggests, the series is not one that is polished and proper. It is an aid to a quick reference and a summary of sorts of the things I'd like to remember.

I'll use the following convention for the title of the post when I create one that belongs to the series: Savio's Notes: Sub-series: Post title

With that introduction I'll now move to the first post in the series, viz., Savio's Notes: Java Book: Effective Java - Chapter 2 - Item 1 to Item 6

FC 10 - A good distribution that can get better

While helping the Sword CTSpace to set up the office during their transition out of Symphony, I had the opportunity to experiment with FC 10, i.e., Fedora Core's latest release, viz., Version 10.

First impression were excellent. This is a release that just great in terms of ease of use and hardware detection. In fact, up until this release, whenever I installed a version of FC on a laptop, I always ended up removing it because the laptop would never work as it was designed to work.

But this time, I had a new laptop, an Acer Extensa 4620 upgraded to 4 GB of RAM which came with Windows Vista Home Basic, 32 bit edition. The 32 bit edition of Vista refused to recognise all 4 GB and a bit of googling, revealed that this is an inherit limitation of the 32 bit OS.

So the alternative was to get a 64 bit OS on the laptop. Since FC-10 was freshly released I thought of using that and also because a 64 bit Vista required me to shell out more cash.

Well sufficient to say, I've tried it for a fortnight now, and I'm so happy I made the decision. Of course, there are a few things that annoy me, but I can live with them. For the record, here is a list of my failures (only because I gave up) with FC10:

1. Dual display support: I failed with this both on the desktop and the laptop. No amount of R&D and trials & errors seemed successful. Finally from most of what I found on the net was that FC had changed the display related architecture from FC9 onwards and it was still in development.
2. Webcam: The webcam doesn't work, but to be fair, I've not really tried to get it to work. (Now working as per update 3)
   
3. Acer Keys: Some of them worked, like the sound, brightness while others (application quick launches) don't. Most of those that don't I rarely ever used even if I were on Windows. So not a big issue for me.
   
4. Bluetooth: This works sometimes and not the rest of the time. When it does work, it's only for file transfers. I still can't get my Nokia to synch my calendar and contacts. I really miss the way Nokia PC Suite works on Windows and wish that Nokia would get a Linux version of PC suite out. ( (Now working consistently as per update 3)
5. Opera: My biggest miss is that I couldn't get Opera for FC10-x64. It just refused to work. And I'm a BIG fan of the browser. I really miss it and currently get by using Firefox. (Now working as per update 1)

But I still think FC10-86x64 is GREAT! I couldn't think of using something else. Well... Maybe Ubuntu, but I've just gotten used to the way FC works I don't think I'll really shift. And of course there's Puppy Linux. Now that's a distribution that so very cool! I wish, we could have something like that for all our Linux distributions. But till that time comes, I'll stick with FC for my larger computers and keep Puppy as part of my the Emergency Rescue kit as well as for my older hardware and basic browsing needs.

However, my final verdict is still is to say with FC8 if you need stability and don't want to be hassled with cutting edge technology issues. But if your willing to rough it out a bit and learn a lot along the way I'd suggest going for FC-10 and you won't be dissappointed.

Update 1

I finally got Opera to work on FC 10. Yippee!!! Well for the record here's what I did to get it to work.

After a bit of a browse through the forums, I realised that there were a few who go it to work and that there is a special 64 bit version that needed to be downloaded. So back to the Opera download web-site. Unfortunately, the site doesn't recognise 64 bit version of linux correctly and hence I had to manually navigate and select the right version to download. Once done, this would not install because of a dependancy on libXt. When I checked, I had libXt installed and the latest version. Then, why???? Few more tries and it dawned on me... Opera wanted the 32 bit version, not the 64 bit version that I had installed!!! Duh!!! That was strange. So after a yum install libXt.i386 I tried installing opera again and success!!!

A bit strange that opera required the 32 bit library, but I won't complain, because I now have my favorite browser working on my favorite OS!!!

Update 2

Found some good stuff at http://www.mjmwired.net/resources/mjm-fedora-f10.html to help in the setup of FC-10. When used with caution and it is quite helpful.

Update 3

I'm not sure what I did but the webcam has begun to work. I do know that I did a yum update and also installed GYachE Improved an improved client for the Yahoo Messenger. After installing the new client I thought I'll check if it supports the webcam and it worked! I then tried Cheese the Webcam Booth, which I had installed earlier. And it worked this time. So another success on FC-10. Yipeee!!!

I also figured out to get the bluetooth to work consistently. I had earlier set the bluetooth applet for gnome to be visible always. After I changed this to be displayed only when bluetooth was active, everything worked well and consistently!

Update 4

I just managed to get Virtual box to recognize the attached USB devices. However to achieve this I needed to run VirtualBox as root. Which is not what I really want to do. Till I figure out on which file(s) I've not got the permissions on I'll make do with having to run it as root.