03. Exercise: Map

Map Exercise

Create a Person class

Task Description:

Let's get some practice with maps. First, let's create a Person class (as we have done a few times in the past!).

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Store and retrieve objects in a HashMap

Task Description:

The following steps will show you how to create a driver program to store and retrieve Person objects in a HashMap.

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Solution

ND079 C1 L6 A03 Maps Exercise Solution

public class MapExcercise {

    public static void main(String[] args) {

        Map<String, Person> mapOfPeople = new HashMap<String, Person>();
        Person mike = new Person("Mike", "mike@email.com");
        Person shaun = new Person("Shaun", "shaun@email.com");
        Person sally = new Person("Sally", "sally@email.com");
        Person cesar = new Person("Cesar", "cesar@email.com");

        ArrayList<Person> people = new ArrayList<Person>();
        people.add(mike);
        people.add(shaun);
        people.add(sally);
        people.add(cesar);

        for (Person person : people) {
            MapExcercise.addToMap(mapOfPeople, person);
        }

        for (String email : mapOfPeople.keySet()) {
            System.out.println(email);
        }

        for (Person person : mapOfPeople.values()) {
            System.out.println(person);
        }

        System.out.println("Get Mike: " + mapOfPeople.get("mike@email.com"));
        System.out.println("Get Jeff: " + mapOfPeople.get("jeff@email.com"));
        System.out.println("Contains Mike: " + mapOfPeople.containsKey("mike@email.com"));
        System.out.println("Contains Jeff: " + mapOfPeople.containsKey("jeff@email.com"));

    }

    private static void addToMap(Map<String, Person> map, Person person) {
        map.put(person.getEmail(), person);
    }

}
public class Person {

    private final String name;
    private final String email;

    public Person(String name, String email) {
        this.name = name;
        this.email = email;
    }

    public String getName() {
        return name;
    }

    public String getEmail() {
        return email;
    }

    @Override
    public String toString() {
        return name + " " + email;
    }

}

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