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  • By Matthew Gilliard
    Working with HTML on the Web Using Java and jsoup Working with HTML on the Web Using Java and jsoup

    So, you need to parse HTML in your Java application. Perhaps you are extracting data from a website that doesn’t have an API, or allowing users to put arbitrary HTML into your app and you need to check that they haven’t tried to do anything nasty?

    Have you tried using regular expressions?  It won’t end well. The author of that now-infamous text managed to recover from their distress enough to suggest using an XML parser (before, presumably, collapsing into the void). The problem with this is that an awful lot of the HTML in the world is not valid XML. People open tags without closing them, they nest tags wrongly, and generally commit all kinds of XML faux pas. Some non-XML constructs are perfectly valid HTML and admirably, browsers just cope with it.

    To adopt the flexible and stylish attitude of web browsers, you really need a dedicated …

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  • By Matthew Gilliard
    Using Twilio Functions with ClojureScript Blog post header: Using Twilio Functions with ClojureScript

    Twilio offers several APIs for programmable communication which rely on webhooks. Twilio Functions is a serverless runtime which can handle these webhooks by running your code on Twilio’s platform to generate customized responses to phone calls, text or WhatsApp messages, emails and more - without having to manage a server yourself. Functions supports JavaScript, and therefore any of the compile-to-js languages can be used too, such as TypeScript.

    Here I’ll show how you can use Shadow CLJS, the Twilio CLI and Serverless Toolkit to create a Twilio Function in ClojureScript. If you want to jump straight to the final code, you can find the project on GitHub.



    Project Setup

    Create a new Shadow CLJS project using npx which is …

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  • By Matthew Gilliard
    Getting Started with JavaFX Getting Started with JavaFX

    JavaFX is a Java toolkit for making GUI applications which run on Windows, MacOS or Linux and mobile. It is the successor to the old Swing and the older AWT toolkits.

    Since the release of Java 11 in 2018 JavaFX has been part of the OpenJDK project, so it is open-source and is developed by many people from many different companies. If you are interested in creating a desktop application today then I would recommend starting with JavaFX and not using Swing or AWT, but it can be hard to know how to get started.

    This post will walk you through creating a JavaFX desktop application from scratch - the application will use JavaFX’s controls module to draw a label with some text, then we’ll move on to creating an interactive app that can send SMS messages.

    What do I need in order to make a JavaFX Application?

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  • By Matthew Gilliard
    Be a Magician by Calculating Powers of Two in Your Head Be a Magician by Calculating Powers of Two in Your Head

    As a programmer you might have to deal with questions like these:

    What's bigger, 243 or 7 trillion?


    How many items can we store if our database uses a 32-bit identifier?

    Gif of someone doing complex math

    Calculations involving powers of two come up often in programming, and it's completely possible to work these out in your head faster than opening your calculator app, using this one (weird?) trick.


    There are three things to remember:

    • First, 2(a+b) = 2a × 2b
    • Second, 210 is 1024, which is really close to 1000.
    • Third, you need to know the powers of 2 up to 210

    Powers of 2 from 1 to 9: 2, 4, 8, 16, 32, 64, 128, 256, 512

    These facts are the basis for the rule:

    Add three zeros for each ten in the power, then multiply by whatever is left.


    What’s bigger, 243 or 7 trillion?

    Using the first fact we can split up the 43 into 4 tens and …

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  • By Matthew Gilliard
    Detecting Robocalls in Java with Twilio Lookup and Nomorobo Detecting Robocalls in Java with Twilio Lookup and Nomorobo

    Twilio's CEO Jeff Lawson recently wrote about the history of robocalls and what we're doing to eliminate them. 

    Until that happens, we can build a tool in Java that will help us identify an unwanted call using the Twilio Lookup API with the Nomorobo Spam Score Add-on.

    Set Up

    In order to create this project you’ll need

    Add the Nomorobo Add-on to your Twilio Account

    Head to the Twilio Console and install the Nomorobo add-on. Look for the yellow logo and click through to "Install".

    Nomorobo Add-on logo

    Leave the name as nomorobo_spamscore and "Save" the Add-On.

    Setting Up your Java Project

    Create a new Maven project with the java8-quickstart-archetype:

    mvn archetype:generate \
     -DarchetypeGroupId=pl.org.miki \
     -DarchetypeArtifactId=java8-quickstart-archetype \
     -DarchetypeVersion=1.0.0 \

    This command will prompt for a groupId and artifactId. If …

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  • By Matthew Gilliard
    How Twilio’s Programmable Voice Saved My Vacation How Twilio's Programmable Voice Saved My Vacation

    After booking some train journeys with Deutsche Bahn (the German rail network) for my summer vacation this year, I found I needed to call their reservations desk to change something important about my tickets. Unfortunately the number they provide is a specially-priced Premium Rate number in Germany, and international calls to these are blocked from my phone. Twilio’s Programmable Voice products are perfect for solving this kind of problem. Read on to find out how I did it and how you could do the same.

    Step 1: Getting A Local Number

    The first thing to do is to get a number which you can call. Twilio’s phone numbers console allows us to buy phone numbers in over a hundred countries so once you have signed up for an account click the “+” button to buy a new number that’s local to you:

    Step 2: Forwarding Incoming Calls

    After buying a …

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  • By Matthew Gilliard
    Getting Started with the Java Streams API Blog Header: Getting Started with the Java Streams API by Matthew Gilliard, Developer Evangelist

    The Streams API was added in 2014 with the release of Java 8 so you’ve almost certainly got it available today. It is used to pass a series of objects through a chain of operations, so we can program in a more functional style than plain iteration allows. Still, when working with collections many developers still reach for the classic for loop.

    In this post, I’ll introduce the terms used when talking about Streams, show some examples of each term and how they can be used together to create compact and descriptive code. Then I’ll show a real-world example of Streams code I wrote recently to pick winners in a raffle.

    What’s a Stream?

    A Stream is a (possibly never-ending) series of Objects. A Stream starts from a Source. The objects in a Stream flow through Intermediate Operations, each of which results in another stream, and are gathered …

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  • By Matthew Gilliard
    How to read and understand a Java Stacktrace Copy of Photo blog Header 2-2.png

    When things go wrong in a running Java application, often the first sign you will have is lines printed to the screen that look like this:

    Exception in thread "main" java.lang.RuntimeException: Something has gone wrong, aborting!
        at com.myproject.module.MyProject.badMethod(MyProject.java:22)
        at com.myproject.module.MyProject.oneMoreMethod(MyProject.java:18)
        at com.myproject.module.MyProject.anotherMethod(MyProject.java:14)
        at com.myproject.module.MyProject.someMethod(MyProject.java:10)
        at com.myproject.module.MyProject.main(MyProject.java:6)

    This is a Stacktrace, and in this post I'll explain what they are, how they are made and how to read …

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  • By Matthew Gilliard
    Coding Twilio Webhooks in Java with Spring Boot OaO_XJW_jNspphskhagxUqwgYna48fdsintjxgUZxg8PQ2Y8D7jBnmUa_g4kwpliEvf3ZB8QaajTv0LZ5Y6QltTsbY3WrscGMWuWw61bS7XvOQO4sglr5cF1xGGFxib6Zomr9J1g

    Twilio’s APIs enable communication in a whole host of ways: by phone, WhatsApp, Facebook, SMS and more.  Usually when events such as incoming messages or calls happen Twilio will make an HTTP request to a server the user provides to discover what it should do - these are called webhooks. HTTP servers can be written with any technology to respond to these webhooks, and for Java developers the most popular framework is Spring Boot.

    In this post we’ll create a Spring Boot app which can respond to incoming phone calls by playing callers a short message followed by the marvellous Rogers and Hammerstein song “It Might As Well Be Spring”.


    Creating a Spring Boot App

    The Spring folks have created the Spring Initializr for quickly creating a new project. Head over to https://start.spring.io …

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  • By Matthew Gilliard
    Using WhatsApp, Twilio and Azure to Generate Photo Alt-text in Java People programming together

    AI services like Computer Vision (CV) are getting easier and easier to play with, and we can have some fun by making them available to use from our cellphones. In this post, we will use Java to connect the Twilio API for WhatsApp with Azure’s CV APIs to create a bot that can describe photos. It would be neat to use this for generating alt-text to help make your images more accessible online, for example.

    We will need the following to get started with this post

    Overview of our app

    How it works

    When Twilio receives a WhatsApp message it will send an HTTP request to a URL we provide.

    Our mission is to create an app in Java which can handle those requests. The app will take the URL of any …

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