What did we learn?

• Predicates are conditions!
• Consumers are actions!
• Comparators compare!
• Map transforms one thing to another!

Assignments

1. Product Filter (Predicate + T)

• Create a generic method filterList(List<T> list, Predicate<T> condition) that returns a new list with only the elements that match the condition.
• Test the method on a list of Product (as before) to filter:
  1. i. Products under 100 kr.
  2. ii. Products that are in stock.
  3. iii. Combination with .and().

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2. Employee Management (Consumer + T)

• Create a generic method forEachApply(List<T> list, Consumer<T> action) that runs action.accept() on each element in the list.
• Test with Employee objects where you:
  1. i. Increase salaries by 10%.
  2. ii. Print information about all employees.

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3. Library (Comparator + T)

• Create a generic method sortList(List<T> list, Comparator<T> comparator) that sorts a list.
• Test with Book objects:
  1. i. Sort by year.
  2. ii. Sort by author.
  3. iii. Sort by year and then title.
• Extra: Create a method maxBy(List<T>, Comparator<T>) that returns the largest book according to a certain comparator.

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4. Student Filter and Sort (Predicate + Comparator + T, R)

• Make a list of Student.
• Create a generic method mapList(List<T> list, Function<T, R> mapper) that converts a list of type T to a list of type R.
• Filter (with Predicate) all those with grades > 70.
• Sort with Comparator by grade (highest first).
• Use mapList to convert the list of Student to a list of String where each element is "Name: [name], Grade: [grade]".

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5. Order Management (Predicate + Comparator + Consumer + T)

• Create a generic method:

public static <T> void processItems(
        List<T> list,
        Predicate<T> filter,
        Comparator<T> sorter,
        Consumer<T> action
) {
    // Code
}

• The method should:
  1. i. Filter the list with Predicate.
  2. ii. Sort with Comparator.
  3. iii. Run Consumer on each element.
• Test with a list Order (id, customerName, amount, completed).
• Filter out only the incomplete orders.
• Sort them by amount (largest first).
• Print all with Consumer.