Saturday, October 18, 2014

Download Oracle JDK from command prompt

Its been really sometime since I blogged anything. Got into too much work both on personal and professional fronts. I will try to be regular henceforth though, hopefully [fingers crossed!!].

Most of my work happens on EC2 and on Linux as our Hadoop env is on EC2. I absolutely adore Linux and shell. And first and foremost thing, being a Java developer, I have to do is, download JDK onto the Linux machines on EC2. And downloading Oracle JDK from Oracle website is difficult due to mandatory license check, which you need to accept before downloading the JDK. With my Linux env being server-only-machines [i.e. without a desktop], there is no way I could download the JDK directly from Oracle website. So, I came up with this small shell script [extending an answer from Stackoverflow] to download JDK from Oracle website from command prompt.

Depending on the OS and platform of the JDK version you intend to download, just modify the array on line#18 in the following script and you can trigger the download on the shell directly.
Hope this script will be helpful for all those who live on and love command prompt.

Wednesday, January 29, 2014

Learning Guava -- Calibrating time using Stopwatch

Many of our day-to-day applications would need calibrating time taken between 2 points. In Java world we either depend on System.currentTimeMillis() or System.nanoTime(). But the pain here is, we have to do the required computations of getting to a proper granularity to understand the time taken.Would n't it be great it to have such an utility class which will give the required information in the granularity we need with minimum amount of boilerplate code?

Stopwatch is one such small and wonderful utility class in Guava which helps in calibrating elapsed time / duration between any 2 points in the logic. The advantage of using Guava's Stopwatch is you can get the elapsed time in any measure i.e. right from nanoseconds to days. This is possible because you can pass an enum argument type of TimeUnit class to get the elapsed time in the desired granularity.

Code snippet for the usage of the Stopwatch class:

Few caveats for using Stopwatch are you should not start an already started Stopwatch. One has to check if the Stopwatch is already running by invoking isRunning() method.
Stopwatch documentation says the following on the same:
Stopwatch methods are not idempotent; it is an error to start or stop a stopwatch that is already in the desired state.

Also, once I got burned down by StopWatch class of Apache Commons Lang. As I was working in an IDE on a Maven project, I could not relate to the difference between Stopwatch of Guava and StopWatch of Commons Lang as the class got auto imported into the code and then spent some 20 minutes trying to check my classpath, IDE setup, etc. Yes how stupid of me, right? So, please be careful in choosing the correct class.

Sunday, January 26, 2014

Learning Guava -- Load properties file using Guava

Guava code snippet for loading a properties file from classpath.

For more info, please check Resources class of Guava.

Wednesday, November 27, 2013

Learning Guava -- Google Guava blog series

​I have been a huge fan of Google Guava from the time I came across it 3 years back.
For starters, Guava is a project which contains many Google's core libraries like collections, caching, math, primitives, concurrency, networking, common annotations, string processing, I/O, refelction and many others.
It is very well designed API. Guava is designed, implemented and maintained by Google Engineers like Kevin Bourrillion and Kurt Alfred Kluever, etc.

Guava follows almost all the excellent patterns and practices mentioned in Effective Java book written by Joshua Bloch, who has designed the impeccable Java Collections API while he was at Sun. Later he joined Google. Under his mentor-ship, Google Guava got wings and became a very well designed and effective API, useful for many situations and scenarios with an ever-growing feature list. I ensure I add Guava dependency as the first thing to my Gradle or Maven build script. Guava makes Java code a lot more readable, clean, simple and elegant. It utilises the Java generics very well.

Consider the following example which I tweeted few months back.
Google Guava sample code

Which of the above versions looks fine? Obviously the second option, aint it?
There are many such examples where Guava wins by a margin compared to normal Java code and or other libraries like commons, etc.

Guava also helps for [in a way] functional programming too. There are few options which are really helpful there as well. Having said that, Guava creators implore the developers not to litter code with too much functional programming which might lead to unreadable code.

I will start with writing few posts on Google Guava with the tag, "LearningGuava". I have been using Guava extensively in almost every project of mine since few years. This will not only help some one else looking for info or starting on Google Guava, but as well as for me also so that I will remember in future if I need any quick snippet on something specific with Guava usage. That being the motivation, I hope it will be of good experience for you and me as well.

This post will have list of all the posts written for Google Guava. This post kinda serves as an Index and quick reference of my Google Guava posts.

  1. Load properties file using Guava
  2. Calibrating time using Stopwatch 

Monday, July 15, 2013

Presented Storm at The Fifth Elephant, 2013

On 11th July, 2013 I hosted a workshop on "Big Data, Real-time Processing and Storm"at The Fifth Elephant, 2013 here in Bangalore.

I have also uploaded the slides of the presentation deck to SpeakerDeck.

The source code I used in this workshop can be found on my GitHub account.

I have also started curating a bundle for Storm and Big Data as such.