supermemo | TypeScript implementation of the SuperMemo | Game Engine library

In order to make a vocabulary practice app in Android, I want to implement the SuperMemo (SM-2) algorithm in Java. This is a popular choice for spaced repetition software and Anki even adopts it as I understand. The source code example given here was difficult (for me) to follow because of the lack of code formatting and because it is written in Delphi.

The author of SuperMemo states:

1. Split the knowledge into smallest possible items.
2. With all items associate an E-Factor equal to 2.5.
3. Repeat items using the following intervals: I(1):=1
   I(2):=6
   for n>2: I(n):=I(n-1)*EF
   where:
   I(n) - inter-repetition interval after the n-th repetition (in days),
   EF - E-Factor of a given item
   If interval is a fraction, round it up to the nearest integer.
4. After each repetition assess the quality of repetition response in 0-5 grade scale: 5 - perfect response
   4 - correct response after a hesitation
   3 - correct response recalled with serious difficulty
   2 - incorrect response; where the correct one seemed easy to recall
   1 - incorrect response; the correct one remembered
   0 - complete blackout.
5. After each repetition modify the E-Factor of the recently repeated item according to the formula:
   EF':=EF+(0.1-(5-q)*(0.08+(5-q)*0.02))
   where:
   EF' - new value of the E-Factor,
   EF - old value of the E-Factor,
   q - quality of the response in the 0-5 grade scale.
   If EF is less than 1.3 then let EF be 1.3.
6. If the quality response was lower than 3 then start repetitions for the item from the beginning without changing the E-Factor (i.e. use intervals I(1), I(2) etc. as if the item was memorized anew).
7. After each repetition session of a given day repeat again all items that scored below four in the quality assessment. Continue the repetitions until all of these items score at least four.

Here are some related (but different) questions on Stack Overflow:

• What is the spaced repetition algorithm to generate the day intervals?
• Open Source implementation of a Spaced Repetition Algorithm in Java
• Spaced repetition (SRS) for learning

How do you implement this in Java?

(I've been working on this recently and I think I have an answer, so I am submitting this as a Q&A pair to help other people doing the same thing.)