Collections.java

import java.util.*; // This is necessary to use collections like List, Set, Map

public class Collections {

    public static void main(String... args) {

        // Wrapper classes ( use them between angle brackets < > )
        // Integer, Double, Boolean
        // Long, Character, Float

        lists();
        sets();
        maps();
    }

    private static void maps() {

        final Map<String, Integer> points;
        points = new HashMap<>();

        points.put("Angel", 10);
        points.put("Ferran", 9);
        points.put("Maria", 15);

        int ferranPoints = points.get("Ferran");
        System.out.println(ferranPoints);

        // Suppose Angel gets 5 points more
        int angelPoints = points.get("Angel");
        angelPoints += 5;
        points.put("Angel", angelPoints);

        System.out.println(points);
    }

    private static void sets() {

        final Set<String> words; // declare variable
        words = new HashSet<>(); // create an empty list
        words.add("zero");
        words.add("one");
        words.add("two");
        words.add("three");
        words.add("four");
        words.add("five");
        words.add("six");

        if (words.contains("one")) {
            System.out.println("Yes!");
        }

        if (words.contains("uno")) {
            System.out.println("Sí!");
        }

        System.out.println("-- for in --");
        int i = 0; // artificial index
        for (String word : words) {
            System.out.println(i + " - " + word);
            i++;
        }
    }


    private static void lists() {

        final List<String> words; // declare variable
        words = new ArrayList<>(); // create an empty list
        words.add("zero");
        words.add("one");
        words.add("two");
        words.add("three");

        // words = Arrays.asList("cero", "uno", "dos", "tres");

        if (words.contains("one")) {
            System.out.println("Yes!");
        }

        if (words.contains("uno")) {
            System.out.println("Sí!");
        }

        System.out.println("-- for in --");
        for (String word : words) {
            System.out.println(word);
        }

        System.out.println("-- for i --");
        for (int i = 0; i < words.size(); i++) {
            System.out.println(i + " -> " + words.get(i));
        }

        System.out.println("-- while --");
        int i = 0;
        while (i < words.size()) {
            System.out.println(i + " -> " + words.get(i));
            i++;
        }
    }

}