The Gacha kata

Learn how to use generics using Java.

Pre-requirements

• OOP knowledge
• Java 11

Description

This kata is about building a gacha machine that we could fill with different type of prize and get them. Gacha machines are quite common in Japan. They are boxes where you introduce a coin and it will give you a random ball that contains some cool minis.

Kata steps

1. First step

   • Checkout first-step branch and have a look to the code to understand it. Then execute the code. If everything is fine it should be failing. You will have more context about the exercise in the main file.
   • Implement GachaMachine#fillPrizes and GachaMachine#getPrize methods
   • If the implementation is ok you should be getting a random superhero in your console. You can always checkout second-step branch in case you are stuck.

2. Second step

   • Paste the following code under the existing one in your main file.

   final var pokemonMachine = new GachaMachine();
   pokemonMachine.fillPrizes(new PokemonPrize());
   final var pokemonPrize = pokemonMachine.getPokemonPrize();
   
   // Should display a random pokemon
   System.out.println(pokemonPrize);
   

   • Modify your GachaMachine to make the code pass.
   • If the implementation is ok you should be getting a random superhero and a random pokemon in your console. You can always checkout third-step branch in case you are stuck.

3. Third step

   • You may end up having a lot of code duplication inside your GachaMachine, but as you may be thinking this will become quite a tedious task to add methods any time you would like to make your gacha machine compatible with more and more prizes. To avoid it we will change our GachaMachine to use generics and make it compatible with any kind of prize.
   • Checkout this lesson and understand generics
   • Make your GachaMachine to work using generics.
   • After coding the solution you should end up having a small GachaMachine class using generics and completed this kata!
   • You can check the final solution checking out final-code branch.

Recommendations

Do this exercise pairing with somebody that already knows how generics work, so your pair can solve any question you have about it.