Java Guild Meeting 5/2018

Gi11i4m
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Generics

New part, new topic! The next topic is Generics. Generics is all about adding generic type parameters to classes, methods etc. in order to make your code more flexible. Generics is not something you commonly need, but it can be helpful when used correctly.

For those who recall the PECS rule, it can be quite frustrating to figure out if you need super or extends. In order to keep the exercises concise and not too complicated (relative to Generics of course, which can already be a mind-fuck), you don't necessarily need to use super to solve the exercises.

If you need to refresh your memory, you can check out some info here. Don't forget that e.g. List<String> is not a subclass of List<Object>, but String[] does inherit from Object[]!.

The first exercise is to implement a function that calculates the union of two lists. There is no code yet, but the second box contains a list of tests (Tech.io).

How to proceed:

  • Work iteratively from the first test to the last, uncommenting one test at a time.
  • Don't alter the test code to make it work ;)
  • KISS! Only inject as much generics as needed to make the test compile
  • You can only proceed once the test compiles and succeeds!

The tests use a class history that is as follows:

  • ChocolateCake extends Cake
  • StuffedChocolateCake extends ChocolateCake
  • VanillaCake extends Cake
Write the implementation
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// {...}
import java.util.ArrayList;
import java.util.List;
public class UnionUtil {
}
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