ImmutableJson.java

public class ImmutableJson {


  private static final ObjectMapper MAPPER = new ObjectMapper();

  public static void main(String[] args) throws IOException {
    // create a student
    final Student student = new Student("John Doe", new Date(), true,
        new Course("Intro to Typing", Department.COMPUTER_SCIENCE, 101),
        new Course("Postmodern Deconstructionism", Department.ENGLISH, 201),
        new Course("Remedial Galois Field Arithmetic", Department.MATH, 51));

    System.out.printf("The original student object is: '%s'%n", student);

    // serialize the student to a JSON object
    final String serialized = MAPPER.writeValueAsString(student);
    System.out.printf("The serialized student is: '%s'%n", serialized);

    // parse the JSON back into a Java object
    final Student deserializedStudent = MAPPER.readValue(serialized, Student.class);
    System.out.printf("The deserialized student object is: '%s'%n", deserializedStudent);
  }


  public static enum Department {
    COMPUTER_SCIENCE("CS"),
    ENGLISH("ENG"),
    MATH("MATH");

    private final String shortName;

    private Department(String shortName) {
      this.shortName = shortName;
    }

    public String getShortName() {
      return shortName;
    }
  }

  public static class Course {

    private final Department department;
    private final String vanityName;
    private final long courseNumber;

    @JsonCreator
    public Course(@JsonProperty("vanityName") String vanityName,
                  @JsonProperty("department") Department department,
                  @JsonProperty("courseNumber") long courseNumber) {
      this.vanityName = vanityName;
      this.department = department;
      this.courseNumber = courseNumber;
    }

    public String getVanityName() {
      return vanityName;
    }

    public long getCourseNumber() {
      return courseNumber;
    }

    public Department getDepartment() {
      return department;
    }
  }

  public static class Student {

    private final String name;
    private final Date dateOfBirth;
    private final boolean enrolled;
    private final List<Course> courses;

    @JsonCreator
    public Student(@JsonProperty("name") String name,
                   @JsonProperty("dateOfBirth") Date dateOfBirth,
                   @JsonProperty("enrolled") boolean enrolled,
                   @JsonProperty("courses") Course ... courses) {
      this.name = name;
      this.dateOfBirth = dateOfBirth;
      this.enrolled = enrolled;
      this.courses = Collections.unmodifiableList(Arrays.asList(courses));
    }

    public String getName() {
      return name;
    }

    public Date getDateOfBirth() {
      return dateOfBirth;
    }

    public boolean isEnrolled() {
      return enrolled;
    }

    public List<Course> getCourses() {
      return courses;
    }
  }
}