Start by downloading CS201_Lab11.zip and importing it into Eclipse. You should see a project called CS201_Lab11.
A Generic Functor interface
The Functor interface defines a very simple kind of functor: one that takes a single argument value, performs some computation on it, and stores the result of the computation in a field or fields:
public interface Functor<E> {
/**
* Apply the functor to a value.
*
* @param value a value
*/
public void apply(E value);
}The ApplyFunctor class contains a single generic method which is useful for working with Functor instances:
public static<E> void applyToArray(E[] arr, Functor<E> functor) {
for (int i = 0; i < arr.length; i++) {
functor.apply(arr[i]);
}
}The applyToArray method takes an array of elements of type E and a Functor<E>, and calls the functor’s apply method on each element of the array. This function may be used to perform a computation on all of the elements in an array.
Your Task
Your task is to implement two classes which implement the Functor interface:
- SumIntFunctor, which implements Functor<Integer>. It computes the sum of all of the Integer values to which it is applied.
- CountJFunctor, which implements Functor<String>. It computers the number of occurrences of the characters ‘J’ and ‘j’ in the String values to which it is applied.
The SumIntFunctorTest and CountJFunctorTest classes implement JUnit tests for both classes.
Hints
The SumIntFunctor and CountJFunctor classes should build up the overall result by updating the value of a field or fields.
Submitting
When you are done, save the project (CS201_Lab11) to a zip file by right-clicking it and choosing
Export…→Archive File
Upload the saved zip file to the Marmoset server as lab11. The server URL is
