A larger program across packages

import java.util.Scanner;
import quiz.logic.Quiz;
import quiz.ui.TextUI;

public class Main {
    public static void main(String[] args) {
        TextUI ui = new TextUI(new Scanner(System.in), new Quiz());
        ui.start();
    }
}

package quiz.ui;

import java.util.Scanner;
import quiz.domain.Player;
import quiz.domain.Question;
import quiz.logic.Quiz;

public class TextUI {
    private Scanner scanner;
    private Quiz quiz;

    public TextUI(Scanner scanner, Quiz quiz) {
        this.scanner = scanner;
        this.quiz = quiz;
    }

    public void start() {
        while (true) {
            System.out.print("> ");
            String command = this.scanner.nextLine();
            if (command.equals("quit")) {
                System.out.println("Bye!");
                break;
            }
            if (command.equals("add")) {
                this.addQuestion();
            } else if (command.equals("play")) {
                this.play();
            } else if (command.equals("best")) {
                this.printBest();
            } else {
                System.out.println("Unknown command: " + command);
            }
        }
    }

    private void addQuestion() {
        String prompt = this.scanner.nextLine();
        String answer = this.scanner.nextLine();
        int points = Integer.valueOf(this.scanner.nextLine());
        this.quiz.addQuestion(new Question(prompt, answer, points));
        System.out.println("Questions: " + this.quiz.getQuestions().size());
    }

    private void play() {
        String name = this.scanner.nextLine();
        Player player = this.quiz.newPlayer(name);
        for (Question question : this.quiz.getQuestions()) {
            System.out.println(question);
            String reply = this.scanner.nextLine();
            if (this.quiz.answer(player, question, reply)) {
                System.out.println("Right!");
            } else {
                System.out.println("Not quite.");
            }
        }
        System.out.println(player);
    }

    private void printBest() {
        Player best = this.quiz.best();
        if (best == null) {
            System.out.println("No one has played yet");
        } else {
            System.out.println("Best: " + best);
        }
    }
}

package quiz.logic;

import java.util.ArrayList;
import quiz.domain.Player;
import quiz.domain.Question;

public class Quiz {
    private ArrayList<Question> questions;
    private ArrayList<Player> players;

    public Quiz() {
        this.questions = new ArrayList<>();
        this.players = new ArrayList<>();
    }

    public void addQuestion(Question question) {
        this.questions.add(question);
    }

    public ArrayList<Question> getQuestions() {
        return this.questions;
    }

    public Player newPlayer(String name) {
        Player player = new Player(name);
        this.players.add(player);
        return player;
    }

    public boolean answer(Player player, Question question, String reply) {
        if (question.isRight(reply)) {
            player.addPoints(question.getPoints());
            return true;
        }
        return false;
    }

    public Player best() {
        Player best = null;
        for (Player player : this.players) {
            if (best == null || player.getPoints() > best.getPoints()) {
                best = player;
            }
        }
        return best;
    }
}

package quiz.domain;

public class Question {
    private String prompt;
    private String answer;
    private int points;

    public Question(String prompt, String answer, int points) {
        this.prompt = prompt;
        this.answer = answer;
        this.points = points;
    }

    public boolean isRight(String reply) {
        return reply.trim().equalsIgnoreCase(this.answer);
    }

    public int getPoints() {
        return this.points;
    }

    @Override
    public String toString() {
        return this.prompt + " (" + this.points + " points)";
    }
}

package quiz.domain;

public class Player {
    private String name;
    private int points;

    public Player(String name) {
        this.name = name;
        this.points = 0;
    }

    public void addPoints(int points) {
        this.points += points;
    }

    public int getPoints() {
        return this.points;
    }

    @Override
    public String toString() {
        return this.name + ", " + this.points + " points";
    }
}