填充嵌套的HashMap

Question

I have a HashMap wich contains a HashMap , and this second HashMap contains another HashMap :

public static final Map<String, Map<String, Map<String, Boolean>>> questionnaireData;

I want my HashMap to be static and final and contains data, so I did the following :

public static final Map<String, Map<String, Map<String, Boolean>>> questionnaireData;
    static {
        Map<String, Map<String, Map<String, Boolean>>> data = new HashMap<>();
        data.put(
            "Architecture des ordinateurs",
            new HashMap<String, Map<String, Boolean>>() {{
                put(
                    "1. La partie du processeur spécialisée pour les calculs est :",
                    new HashMap<String, Boolean>() {{
                        put("L’unité mathématique", false);
                        put("Les Registres", false);
                        put("L’unité arithmétique et logiqueue et logique", true);
                        put("UCC", false);
                    }}
                );
                put(
                        "2. Dans un ordinateur, les données sont présentées par un signal électrique de la forme :",
                        new HashMap<String, Boolean>() {{
                            put("Analogique", false);
                            put("Numérique", true);
                            put("Alphanumérique", false);
                            put("Alphabétique", false);
                        }}
                    );
                put(
                        "3. Les différents éléments d’un ordinateur (mémoire, processeur, périphériques…) sont reliés entre eux par des:",
                        new HashMap<String, Boolean>() {{
                            put("Fils/câbles", true);
                            put("Registres", false);
                            put("Cartes d’extensions", false);
                            put("Bus", false);
                        }}
                    );
            }}
        );
        data.put(
                "Bureautique",
                new HashMap<String, Map<String, Boolean>>() {{
                    put(
                        "1. Quelles sont les fonctions d’un logiciel de traitement de texte ?",
                        new HashMap<String, Boolean>() {{
                            put("Mise en page d’un texte", true);
                            put("Compilation d’un texte", false);
                            put("Présentation d’un texte sous forme de diaporama  ", false);
                            put("Edition d’un texte", true);
                        }}
                    );
                    put(
                            "2. Insérer des lignes supplémentaires dans un tableau Word :",
                            new HashMap<String, Boolean>() {{
                                put("Cela n'est pas possible et il faut calculer dès le départ le nombre de lignes qui seront nécessaires.", false);
                                put("Peut se faire à n'importe quel moment en allant dans la dernière cellule du tableau et en appuyant sur la touche Espace.", false);
                                put("Peut se faire à n'importe quel moment en utilisant le menu Tableau - Insérer Lignes.", true);
                                put("Peut se faire à n'importe quel moment en allant dans la dernière cellule du tableau et en appuyant sur la touche Entrer.", false);
                            }}
                        );
                    put(
                            "3. Qu’est ce qu’une cellule :",
                            new HashMap<String, Boolean>() {{
                                put("La cellule est une colonne.", false);
                                put("La cellule est une ligne.", false);
                                put("Aucune des deux réponses.", true);
                            }}
                        );
                }}
            );
        questionnaireData = Collections.unmodifiableMap(data);
    }

I heard that using anonymous class can make problems, but I can't find any other method than this.

In fact, There is a method where I have to declare and populate a HashMap and use it as an argument for the parent HashMap , but in my case I'll end up with hundreds of declarations.

What do you think about my code? and if there is some better method, please let me know.

Answer 1

Since you asked for an example, here we go.

Topic:

package com.answer.stack.overflow.questionnaire;

import java.util.Set;
import java.util.TreeSet;

public class Topic {
  private String title;

  private Set<Question> questions = new TreeSet<Question>();

  public Topic(String title) {
    this.title = title;
  }

  public String getTitle() {
    return title;
  }

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

  public Set<Question> getQuestions() {
    return questions;
  }

  @Override
  public String toString() {
    String text = "Topic is ... " + title + "\n";

    for (Question question : questions) {
      text += question.toString() + "\n";
    }

    return text;
  }
}

Question:

package com.answer.stack.overflow.questionnaire;

public class Question implements Comparable<Question> {
  private String text;
  private String code;

  private Answer correctAnswer;

  public Question(String code, String text, String correctAnswerText) {
    this.code = code;
    this.text = text;
    this.correctAnswer = new Answer(code, correctAnswerText);
  }

  public String getText() {
    return text;
  }

  public String getCode() {
    return code;
  }

  public boolean isCorrect(String answer) {
    return correctAnswer.getText().equalsIgnoreCase(answer);
  }

  @Override
  public int compareTo(Question o) {
    return code.compareToIgnoreCase(o.code);
  }

  @Override
  public String toString() {
    return code + ": " + text + " (" + correctAnswer.getText() + ")";
  }
}

Answer:

package com.answer.stack.overflow.questionnaire;

public class Answer {
    private String code;
    private String text;

    public Answer(String code, String text) {
        this.code = code;
        this.text = text;
    }

    public String getText() {
        return text;
    }

    @Override
    public String toString() {
        return code + ": " + text;
    }
}

Questionnaire:

package com.answer.stack.overflow.questionnaire;

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

public class Questionnaire {
  private List<Topic> topics = new ArrayList<Topic>();

  public void addTopic(Topic topic) {
    topics.add(topic);
  }

  public void checkAnswers(Map<String, String> answers) {
    for (Topic topic : topics) {
      for (Question question : topic.getQuestions()) {
        String code = question.getCode();
        String answerText = answers.get(code);

        if (answerText == null) {
          System.out.println("Answer not provided for question " + code + ".");
        } else if (!question.isCorrect(answerText)) {
          System.out.println("\"" + answerText + "\" is an incorrect answer for question " + code + ".");
        } else {
          System.out.println("Question " + code + " was answered correctly!");
        }
      }
    }
  }

  @Override
  public String toString() {
    String text = "";

    for (Topic topic : topics) {
      text += topic.toString() + "\n";
    }

    return text;
  }

  public static void main(String[] args) {
    Questionnaire questionnaire = new Questionnaire();
    Map<String, String> answers = new HashMap<String, String>();
    Topic topic = new Topic("My attributes");

    topic.addQuestion(new Question("1A", "What is my name?", "Anonymous"));
    topic.addQuestion(new Question("1B", "How tall am I?", "190 cm"));

    questionnaire.addTopic(topic);

    topic = new Topic("Maths");

    topic.addQuestion(new Question("2A", "How much is 1+1?", "2"));
    topic.addQuestion(new Question("2B", "How much is 3/0?", "Not a number"));

    questionnaire.addTopic(topic);

    System.out.println(questionnaire.toString());

    answers.put("1B", "190 cm");
    answers.put("2A", "2");
    answers.put("2B", "infinite?");

    questionnaire.checkAnswers(answers);
  }
}

Output:

Topic is ... My attributes
1A: What is my name? (Anonymous)
1B: How tall am I? (190 cm)

Topic is ... Maths
2A: How much is 1+1? (2)
2B: How much is 3/0? (Not a number)

Answer not provided for question 1A.
Question 1B was answered correctly!
Question 2A was answered correctly!
"infinite?" is an incorrect answer for question 2B.

Note that you should read all the questions from a file, like qqilihq suggested, instead of hard coding them into your program.

Also this isn't an optimized version by all means. Point was to just demonstrate how to solve the same problem with custom classes. You may want to look into visitor pattern for checking answers in an elegant and easy way and subclassing different types of answers for instance.