Fortsätt till huvudinnehåll

Gradle and some notes on creating Java objects from JSON strings

This morning I spent my time commuting to work reading about a Test-Driven Development Stack for Java. Tools mentioned were Maven, Jetty, Mockito, and JAX-RS. I wanted to learn some more about Mockito so I spent some time reading on their website where I found out about this build automation system called Gradle that can be used instead of Maven. Interesting I thought, let's try it out.

So first things first. The Ubuntu repositories only contained a really old version of Gradle so I downloaded the binary distribution from the website. Installation consisted of the tricky task to decide where to extract the archive and set up my PATH to include the bin directory for Gradle.

Then I thought that I wanted a plugin for Eclipse so I can create Gradle projects and have some parts automatically generated. After searching the web for a short while I found Buildship that is a collection of Eclipse plug-ins that provide support for building software using Gradle.
The easiest way to install it in Eclipse is to use the Eclipse-Marketplace. A nice tutorial written by Lars Vogel can be found here.

 Now that I had a Gradle project in Eclipse it was finally time to pick up on the JSON in Java mini-project I started on yesterday. Adding Google's JSON Java library to the Gradle project was a piece of cake. Just add the line compile 'com.google.code.gson:gson:2.6.2' in the dependencies section of the build.gradle file and you are ready to go.

 Using the GsonBuilder makes it really pleasent to create Java objects from JSON strings. I created a simple User class with the private variables 'name' and 'age' and created new users by calling
User user = new GsonBuilder().create().gson.fromJson(jsonString, User.class);

 You Java developers are really spoiled with nice tools and cool libraries ;).

Kommentarer

Skicka en kommentar

Populära inlägg i den här bloggen

Does TDD really improve software quality?

I have asked myself this question several times, and searched for answers, without coming up with any clear answer. Therefore I have decided to go hard core TDD for a longer period of time (at least 6 months) to really evaluate the effects. There are several things that I find confusing when it comes to TDD. One example is what actually defines a unit test. What is a "unit" anyway? After reading a bit about it I found a text claiming that the "unit" is "a unit of work", i.e. something quite small. Like converting a string to UPPERCASE or splitting a string into an ['a','r', 'r', 'a', 'y'] of chars. This work is usually performed by a single call to a single method in a single, isolated, class. So, what does it mean that a class is isolated? Does it mean that it doesn't have any dependencies to other classes? NO! In the context of TDD it means that any dependencies are supplied by the test environment, for exa...
3 kommentarer
Läs mer

Codility tasks - Part I

I was recently faced with two codility tasks when applying for a job as an Embedded Software Engineer. For those of you who arn't familiar with Codility you can check out their website here:  www.codility.com Task one - Dominator The first task was called Dominator. The goal was to, given a std::vector of integers, find an integer that occurs in more than half of the positions in the vector. If no dominator was found -1 should be returned. My approach was to loop through the vector from the first to the last element, using a std::map to count the number of occurences of each integer. If the count ever reached above half the size of the vector I stopped and returned that integer and if I reached the end without finding a dominator I returned -1. So was that a good approach? Well, the reviewer at the company rated the solution as 'pretty ok'. His preferred solution was store the first integer in the array and set a counter to 1. Then loop through the remaining i...
7 kommentarer
Läs mer

Codility tasks - Part II

Now, the second codility task I was faced with was a bit tougher. The goal was to create a function that, given a vector of integers A and an integer K, returned the number of integer pairs in the vector that, when added, sums up to K. Let me give you an example. Assume that you are given a vector A = [0, -1, 3, 2, -5, 7] and K = 2. Possible combinations to get K are (0, 2), (-1, 3), (3, -1), (2, 0),  (-5, 7), and (7, -5). In other words, the function should return 6. Now, how did I solve this task? The first solution that came to mind involved nested for-loops. The outer loop picking one integer at the time from the vector and the inner loop adding the integer to the others one by one to see if the result is K. This solution works, but it does not scale well. Time complexity will be O(N**2) ,   something that for large vectors will result in very long execution times. My second approach was to use my old friend, the integer counter, and count all occurences of each...
2 kommentarer
Läs mer