Ever since I advanced beyond the “hello worlds” of Java, I had never stopped coding. This section is for documenting code usages that I had employed while solving the technological problems that I had encountered.

How to sort a python dictionary by keys

I am a fan of hash tables when I need to implement logic that augments computation results to a common data structure that need to be used across several function bodies. The ability of the hash table in providing constant access by key helps me in keeping my logic from taking too much time to complete.

Python’s version of hash tables are known as a dictionaries or associative arrays. Apart from augmenting computation results to values of my Python dictionaries, one common task that I often perform is sorting the results by the dictionary keys. In this post, I document how I can sort my Python dictionary by its keys.

How to generate n-grams in Python without using any external libraries

There are many text analysis applications that utilize n-grams as a basis for building prediction models. The term “n-grams” refers to individual or group of words that appear consecutively in text documents.

In this post, I document the Python codes that I typically use to generate n-grams without depending on external python libraries.

Ways to implement the Singleton pattern in Java

After you got started with Java programming, chances are you will want to use some design patterns to organise your Java classes.

One common object oriented design pattern is the Singleton pattern. The Singleton pattern is a technique where you can apply to ensure that there is only one instance of your Java class per runtime.

The Singleton pattern is usually used for grouping functionalities that allow callers to act on a single set of state. Examples of cases where the Singleton pattern can be applied include:

  • A class that keeps track of a customized configurations from a configuration file.
  • A class that facilitates interactions with a database system.
  • A class that performs logging.
  • A class that caches data read from previous database calls.

This post documents some ways to implement the Singleton pattern in Java.

Getting started with Java programming

The Java programming language is a powerful tool for people to get computers to help perform work on behalf of humans. Since its inception, it had been well adopted by many companies in the creation of many great services and technologies.

This post is for my younger self and people who wanted to get started in learning Java programming but find it hard to get started.

How to manually create the jar file for running your Java application

Advances in software engineering had shortened the time needed to build an application from scratch. For instance with Spring Boot, I can easily build my own web API backed by a web server of my choice into a single jar file. By running that jar file, I can start a process that responds to HTTP requests directed at my customized endpoints.

However, not knowing how that jar file is formed and read by the Java Virtual Machine can cloud our understanding of application development with Java. To help understand Java application development better, I described how to manually create a jar file for running a Java application.

How to look for unittest.TestCase subclasses defined in random Python scripts and run them in one shot

To ensure robustness of our Python application, members of the team had written unit test cases to assert that the various code units of the application are working as intended. Unit test cases that are meant to test the same program component are placed together as functions of the same class and contained in a Python script.

As the Python application grows, the number of test scripts grew as well. In an attempt to perform automated unit testing with Jenkins, the first thing that I did was to write a Python script that will look for all the test cases in the application directory and run them at one go.

This post describes the Python script in detail.

How to look for classes defined in Python 3 files dynamically

There are times when we need to write Python codes that extends the functionality of others, especially when we are writing a framework that allows for custom extension. To allow my Python program to be extended by others via the template design pattern, the first exploration task that I did was to find out how to dynamically look for classes defined in arbitrary Python files.

This post documents a way to look for classes defined in Python 3 files dynamically.

How to traverse all folders and files within a folder dynamically in Python 3

I had this requirement where I need to be able to look into a folder and pick up any configuration files for my Python 3 application. In order to achieve that, I first set an exploratory task to get the Python 3 code for traversing all folders and files within a folder.

For this exploratory task, I had created a script that will traverse the folders and files that are contained within a folder and print out their full paths.