They weren't random. They were alphabetical. The first letter of the name always shifted to the next letter in the alphabet.

• Cupcake (Android 1.5)

• Donut (Android 1.6)

• Eclair (Android 2.0–2.1)

• Froyo (Android 2.2)

• Gingerbread (Android 2.3)

• Honeycomb (Android 3.0–3.2)

• Ice Cream Sandwich (Android 4.0)

• Jelly Bean (Android 4.1–4.3)

• KitKat (Android 4.4)

• Lollipop (Android 5.0–5.1)

• Marshmallow (Android 6.0)

• Nougat (Android 7.0–7.1)

• Oreo (Android 8.0–8.1)

• Pie (Android 9)