Module 3 - JSON Serialization

Learning Objectives

• Define the terms serialization and deserialization
  Serialization is the process of converting an object into a format that can be easily stored or transmitted, while deserialization is the reverse process of reconstructing an object from the serialized format.
• Explain why serialization is used to transfer data
  Serialization enables data exchange between different systems, platforms, or programming languages by converting objects into a standardized format that can be transmitted over networks or stored persistently. This facilitates interoperability and is essential for web services, microservices, and distributed systems.
• Implement code that serializes a class to JSON
  Using Jackson's ObjectMapper, you can convert Java objects into JSON strings with simple method calls, with options for formatting and customization.

  // Create a Java object
  User user = new User("john.doe", "John Doe", 30);
  
  // Create ObjectMapper instance
  ObjectMapper mapper = new ObjectMapper();
  
  // Serialize to JSON string
  String jsonString = mapper.writeValueAsString(user);
  
  // Serialize to JSON file
  mapper.writerWithDefaultPrettyPrinter()
    .writeValue(new File("user.json"), user);
  
• Implement code that deserializes a provided JSON string to an object of the class it represents
  Deserializing JSON strings back into Java objects involves using the ObjectMapper's readValue methods with the appropriate type information.

  // JSON string to deserialize
  String json = "{\"username\":\"john.doe\",\"name\":\"John Doe\",\"age\":30}";
  
  // Create ObjectMapper
  ObjectMapper mapper = new ObjectMapper();
  
  // Deserialize to User object
  User user = mapper.readValue(json, User.class);
  
  // Deserialize from file
  User userFromFile = mapper.readValue(new File("user.json"), User.class);
  
  // Deserialize to collection
  List<User> users = mapper.readValue(usersJson,
    mapper.getTypeFactory().constructCollectionType(List.class, User.class));