Challenges

Remember the rules for this are

• Try to use only the information given up to this point in this book.
• Try not to give up until you've given it a solid attempt

Challenge 1.

Replace uses of the "concrete" collection types (ArrayList, HashMap, HashSet) in the following code with the corresponding collection interfaces.

You want to keep the calls like new ArrayList - only change how variables are typed.

import java.util.ArrayList;
import java.util.HashMap;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;

class Main {
    void main() {
        ArrayList<String> jedi = new ArrayList<>();
        jedi.add("Luke");
        jedi.add("Anakin");
        jedi.add("Qui-Gon");
        jedi.add("Obi-Wan");

        HashSet<String> sith = new HashSet<>();
        sith.add("Palpatine");

        HashMap<String, String> winningMatchups 
            = new HashMap<>();
        winningMatchups.put("Anakin", "Palpatine");
        winningMatchups.put("Obi-Wan", "Jar-Jar");

        for (var j : jedi) {
            IO.println(j + " is a jedi");

            var matchup = winningMatchups.get(j);
            if (matchup != null) {
                if (sith.contains(matchup)) {
                    IO.println(j + " would win against " + matchup);
                }
                else {
                    IO.println(j + " would win against " + matchup + " (but they aren't sith)");
                }
            }

        }
    }
}

Challenge 2.

Call methodB using the array returned from methodA.

class Main {
    String[] methodA() {
        return new String[] {
            "Chewbacca",
            "Attichitcuk",
            "Mallatobuck",
            "Lumpawaroo"
        }
    }

    void methodB(List<String> character) {
        IO.println("Characters in the Star Wars Christmas Special:");
        IO.println("----------------");
        for (item : character) {
            IO.println(item);
        }
    }

    void main() {
        // CODE HERE
    }
}