I already implemented Ksoji's 'jfugue-android' library (https://github.com/kshoji/JFugue-for-Android/tree/master/jfugue-android) in my project, but I can't do anything with it, for example initialize it by typing:
MidiSystem.initialize(this);
since Eclipse doesn't seem to know what MidiSystem is at all and I can't fix the problem. Should I import anything else to my project in order to be able to play some simple patterns on an Android device?
Kshoji's Project doesn't provide the sound playback.To play MIDI notes on application, The USB MIDI devices or BLE MIDI devices will be needed.
In case you want to do that, I recommend you build your project using Android Studio instead of Eclipse.
I did a Library that is kind of a solution to have Music Strings played on Android, check it out: https://github.com/ziad-halabi9/AlgorithmicMusicPlayer
It basically takes a musical strings such as "A5s B5q E6h" and converts it into a wav file of a certain instrument. It can also handle multiple instruments at the same time.
You have to chose between BLE or USB interfacing
And write the type of code consequently, for example USB
UsbMidiSystem usbMidiSystem = new UsbMidiSystem(this);
usbMidiSystem.initialize();