Audio Player App - Where do I start?

I need to make an audio player app that does the following:

  1. Has a home screen with a user-friendly interface and various ways to “sort by”, so that I may see the categories exactly how I want to.

  2. Each category should have sub-categories of it’s own, all arriving to a list of final objects beyond which there is no hierarchy remaining.

  3. Selecting the object should play an audio file linked to it (.mp3, .wav, .ogg etc).

  4. Upon selecting the object, a bunch of controls should appear, such as a play/pause button, previous button, next button, and a progress bar that I can use to drag myself to any point in the audio file.

  5. I should be able to “flag” or “mark” any object I want to, and leave a footnote or a comment (which I should be able to access and read later on anytime I want to).

Maybe it’s simple, maybe it’s complicated, I don’t know. I am a complete beginner with no app development experience, and it sounds pretty complicated to me. But I do not know which programming language and software would be ideal for this particular purpose, and how I would go about achieving this goal. I always wanted to get into this field, and now thanks to Covid-19, I have time to learn app development and programming, and build the aforementioned app. Plus this skill will give me something to fall back on if things go south.

If it is at all important, I have an Android phone (EUI Rom, Lollipop), which is what will be running this app, and a Laptop (Windows 7 Professional), which is what I will use to make this app. So, what am I looking for?

It depends hugely on the goals. For example:

  • if you want to publish app as a product you will need 2 apps: one for android and one for ios. In this case you can start with Flutter: https://flutter.dev/

  • if you only interested in android platform: then you shall probably start learning Java or Kotlin

That is a definitive answer, I appreciate that. To clarify, I am not looking to publish it, it’s for personal uses only, and maybe to add to my portfolio/resume going forward, but it won’t be going on any playstore or appstore.
I might gain interest in iOS going forward, but as of now, I can’t afford an iPhone, so I have no reason to even contemplate iOS development and cross-platform compatibility. I have an Android phone, and hence, keeping this project strictly within the bounds of Android makes sense.

That being said, I see there are a few tutorials on Free Code Camp’s website and channel, and I don’t know where to start. For Java, I have found four tutorials.

  • Intro to Java
  • Functional Programming in Java
  • Learn Java 8
  • Learn JavaScript

I don’t know which one would be appropriate for this. I also don’t know if Java is related to Java 8 or JavaScript in any manner.

As for Kotlin, I found three video tutorials on the channel.

  • Tutorial for Beginners
  • Fundamentals Tutorial - Full Course
  • Build Native Apps with Kotlin

That being said, could you point me toward the correct tutorials and the order to watch them in? Also, any other advise that might come in handy? Maybe links to some software that might be useful? Anything out of whatever is mentioned in the tutorials above?

To play audio on android using java you want this library here https://github.com/bytedeco/javacv . It is what I used for my java based music player here https://macmanmatty.github.io/dominate7thUsage/. You will most likely also need this library here http://www.jthink.net/jaudiotagger/ to read the tags and if you wish to play / read .cue files I have a java based library I will be uploading for that soon. I will also be making an android version of my player at some time called sub-dominate7th using glueon.