Higher order functions are those functions that can return functions as their results. The returned function can then be invoked in the same way as you would invoke a normal function. In programming languages like Python, where functional programming is treated as a first class citizen, you can easily define higher order function like this.

def adder(a):
 def add(b):
  return a + b
 return add
add_with_5 = adder(5)
final_value = add_with_5(1)

Java on the other hand introduced functional programming in version 1.8. The support is still very primitive and it does not allow one to create higher order functions that return functions.

I had a weird problem today when my perfectly indented code comments from Vi editor were looking like a mess in Geany.

The pound signs were all out of line though they look perfectly aligned when opened in Vi editor. Initially I thought that it was a problem with the tab settings in Geany. But after tweaking some of the tab settings did not produce any result, I noticed that spaces in Geany were having lesser width compared to other characters, which was the root of the problems. I found that the font that I was using in Geany was not fixed width. And for that I should use Mono variation of the fonts. So I changed the font setting in Edit > Preference > Interface > Fonts > Editor to below:

A few days back at work I was trying to open a fairly large unformatted (a single line) JSON file generated through one of the junit tests. At first I tried to open it in Eclipse since my Eclipse JEE IDE contains an inbuilt JSON formatter but it ended in a disaster! So much so that I had to kill the Java process running Eclipse. Then I tried to open it using Mousepad, the default text editor that comes pre-installed with Xubuntu. It also failed and got hung. I even tried with Gedit but still no luck. I copied the file to a Windows machine and opened it using Notepad++. The online JSON formatters were able to prettify it, so I went on with it then. But the fact that I was not able to open it natively on my system was bugging me.

This week and last week I spent a lot of time writing code to implement the persistence feature for our module with EJB 3 at work. This is the first time I was working with EJB so there was quite a bit of learnings involved. During this time, I noticed that even some of the most seasoned developers don't have a very clear idea about how the whole Persistence thing in JPA works under the hood. They would take some of the things for granted like if they use an EntityManager in their managed objects, something will auto-magically manage everything for them and in the process, did some rookie mistakes.

try-with-resource is the new feature introduced in Java 1.7 to automatically close a resource after using. It basically helps you to avoid a finally block at the end of the try-catch block to close any resource that needs closing like the BufferedReader. But there's a catch. You can not use any type of resource with a try-with-resource block, only those classes that extend java.lang.AutoCloseable can be used, an interface that has a single method: