20. Solution: Jackson

Solution: Jackson

Main.java

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;

import java.nio.file.Files;
import java.nio.file.Path;
import java.time.Duration;
import java.time.Instant;
import java.time.ZoneId;

public final class Main {
  public static void main(String[] args) throws Exception {
    if (args.length != 1) {
      System.out.println("Usage: Main [file path]");
      return;
    }

    UdacisearchClient client =
        new UdacisearchClient(
            "CatFacts LLC",
            17,
            8000,
            5,
            Instant.now(),
            Duration.ofDays(180),
            ZoneId.of("America/Los_Angeles"),
            "555 Meowmers Ln, Riverside, CA 92501");

    Path outputPath = Path.of(args[0]);
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.registerModule(new JavaTimeModule());
    objectMapper.writeValue(Files.newBufferedWriter(outputPath), client);

    System.out.println("Wrote to " + outputPath.toAbsolutePath().toString());

    UdacisearchClient deserialized =
        objectMapper.readValue(Files.newBufferedReader(outputPath), UdacisearchClient.class);
    System.out.println("Deserialized " + deserialized);
  }
}

How does it work?

You may be wondering how Jackson works. After all, you didn't even have to change the UdacisearchClient like you did in the Java Object Serialization exercise!

The secret is sauce Java Reflection. Jackson uses Java's Reflection APIs to examine the UdacisearchClient class structure at run time, and make serialization/deserialization decisions based on what it finds. You'll learn more about Reflection in Lesson 4.