Coding

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 use Java to check whether a domain exists without any external libraries

You wanted to buy a domain for your personal website. You found a whois service and it told you that your domain is available. You are elated and tried to acquire the domain through your favourite registrar. However, your registrar told you that the domain had already been taken.

Isn’t that frustrating? Well, it happened to me once and I was determined never to use the whois service of those unscrupulous sites ever again.

So how can you check whether a domain name is available by yourself? When you have a computer at hand, you can find several ways to do so. In this post, I share how you can check whether a domain exists with the Java programming without using any external libraries.

How to capture the coordinates of your mouse as it moves along a path with jQuery

When you want to move an object on your web page, you can do so by setting the top and left property of that object to several screen coordinates along a path of travel. Although you can create those coordinates by hand, it is more efficient to capture those coordinates using your mouse.

Previously, I had discussed:

In this post, we extend those ideas to build a simple mechanism that captures the coordinates of your mouse as it moves alone a path.

How to set environment variables for your Python application from PyCharm

The Twelve-Factor App methodology recommends storing configurations in the environment.

When you follow this methodology and want to run your Python application from PyCharm, you need to create a customised run configuration.

In case you need it, this post shows how to set environment variables for your Python application from PyCharm.

How to associate a virtual environment with a Python project in PyCharm

When it comes to Python development, PyCharm is my favourite IDE.

Before working on a new Python project, I like to create a virtual environment and associate it with the corresponding PyCharm project. In case you like this mode of operation, this is how you can associate a virtual environment with a Python project in PyCharm.

How to read temperature and humidity from a DHT11 sensor that is connected to a Raspberry Pi 3

I had always wanted to measure the temperature and humidity of the environment where my herbs are grown at.

Since I had a few pieces of Raspberry Pi 3 lying around the house, I decided to use one of them to measure the temperature and humidity of the area of the house where my herbs are.

An additional sensor is required to measure the temperature and humidity of the environment. Therefore, I went to AliExpress and got a DHT11 sensor. By connecting a DHT11 sensor to my Raspberry Pi 3, I can give it the ability to read the temperature and humidity of its environment.

Given these points, I created this post to show how to read temperature and humidity from a DHT11 sensor that is connected to a Raspberry Pi 3.

In order for us to check the temperature and humidity from the DHT11 sensor, we will build a simple Flask application that returns the temperature and humidity values as HTTP responses to HTTP clients.

Building a Raspberry Pi 3 prototype camera that takes a picture at the press of a button

A fun way to test your Raspberry Pi Camera on your Raspberry Pi 3 is to build a prototype that takes a picture at the press of a button. Through such an activity, we will be able to experience:

  • connecting a button to the GPIO ports on a Raspberry Pi.
  • setting up a camera through the CSI interface of a Raspberry Pi.
  • preparing an operating system, such as Raspbian Stretch Lite , for running Raspberry Pi projects.
  • coding a Python 3 script that interacts with the GPIO port and camera on a Raspberry Pi.
  • running a Python 3 script when Raspberry Pi powers on.

Given these points, this post shows how you can build a Raspberry Pi 3 prototype camera that takes a picture at the press of a button.

How to use Python 3 Pillow on Raspbian Stretch Lite to compress your jpeg image

When you are building a Raspberry Pi camera project, you may want to compress the images captured from the camera to reduce the time to upload your image to a server endpoint. Moreover, when you connect your Raspberry Pi to your iPhone Personal WiFi hotspot, you will want to incur minimal mobile bandwidth charges from demonstrating your Raspberry Pi project in your class.

You may have either:

In this case, you will have the option to use Pillow, a fork of Python Imaging Library, to compress your jpeg image.

Flexible CSS rule-sets to keep your images within their parent element

Since an image is worth a thousand words, we use images in your webpage to express complex ideas succinctly.

By default, if we do not specify any dimensions for an image, most browsers will show the image according to its actual size. In this situation, an image will appear to spill over the boundaries of its parent element if it is bigger.

For example, the following screenshot shows the image at https://commons.wikimedia.org/wiki/File:LARGE_elevation.jpg spilling over its parent element:

Example of large image overspilling the parent container

One way to prevent a larger image from going beyond the boundaries of its parent element is to give a standard width to all images. However, if the actual width of an image is smaller than the given width, the image will be stretched:

Example of small image being stretched to fill parent container

This post shows the CSS rule-sets that you can use for flexibly keeping images within their parent element.

How to upload a file and some data through HTTP multipart in Python 3 using the requests library

Undeniably, the HTTP protocol had become the dominant communication protocol between computers.

For example, when we want to upload a file and some data from to a HTTP server, we do so through a HTTP multipart request.

So how can we do that in Python? In Python 3, we can use the services of the requests library to help us construct HTTP multipart request easily.

In case you need it, this is how to upload a file and some data through HTTP multipart in Python 3 using the requests library.