As a way of demonstrating how to write code with Akka, Scala, and functional programming (FP), I started creating a new project this weekend. I named it Aleka, because it may eventually be like Amazon’s Echo/Alexa, written with Akka (and Scala).
(I suppose a better name might be “Ekko,” after Echo, but I have a niece named Aleka, so unless she objects, this works for me.)
As a quick note and a little bit of source code sharing, I wrote the following Perl script to delete all of the binary files it finds in a list of files it’s given. I named this script deleteBinaryFiles.pl, and it should be called like this:
where listOfFilesToLookAt is a file that contains a list of filenames, with one filename per line.
Given that brief introduction, here’s the source code:
As a note to self, when you’re writing an Android application and you think you want to store some static text in an external file, a better approach can be to create a resource file under res/values.
For example, I’m currently adding some help text to an Android app, and to do that I created a file named strings_help.xml under the res/values directory. That file contains HTML wrapped in an XML CDATA tag, like this:
This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 9.7, “How to create a method that returns a function in Scala.”
You want to return a function (algorithm) from a function or method.
Define a function that returns an algorithm (an anonymous function), assign that to a new function, and then call that new function.
The following code declares an anonymous function that takes a
String argument and returns a
This is an excerpt from the Scala Cookbook (partially modified for the internet). This is Recipe 4.16, “How to create inner classes in Scala.”
You want to create a Scala class as an inner class to help keep the class out of your public API, or to otherwise encapsulate your code.
Declare one class inside another class. In the following example, a case class named
Thing is declared inside of a class named
If you need to write an Android
onTouchEvent method inside a
View class, here’s some example source code (boilerplate/skeleton code) that shows how to implement this method, including how to use the
MotionEvent in the method, and how to get the x and y location of the touch event:
I just got back into using an Android
AsyncTask, and it took me a little while to re-load the concepts in my head. I used
AsyncTask’s a few years ago, but haven’t used them since.
To help remember how they work, I created a little
AsyncTask example project, and I’ve included all of the source code for that project here. I’ll show all of the source code for my classes and configuration files, and then explain the code at the end.
Creating a Preferences screen in Android isn’t too hard. The website rominirani.com has a very good preferences tutorial that just needs a minor update for Android 5, as a piece of the code shown there has been deprecated.
To create an Android Preferences UI, just follow these steps:
Sending/displaying a notification is one of the easy things to do in Android. To create and display an Android notification, all you have to do is: