How to load YAML data and map to Java Objects in SnakeYAML?

In this tutorial, we will learn how to map YAML data to Java Objects in SnakeYAML.

Mapping to Java Object

src/main/resources/person.yml

name: Joe
phone: 111-111-11111
address: Park Dr, Charlie Hill

public class Person {
  private String name;
  private String phone;
  private String address;
    .............
}

public class LoadAsJavaObject {
  public static void main(String[] args) throws IOException {
      Yaml yaml = new Yaml();
      try (InputStream in = LoadAsJavaObject.class
              .getResourceAsStream("/person.yml")) {
          Person person = yaml.loadAs(in, Person.class);
          System.out.println(person);
      }
  }
}

Output

Person{name='Joe', phone='111-111-11111', address='Park Dr, Charlie Hill'}

Mapping to list of Java objects

src/main/resources/persons.yml

persons:
 - name: Joe
   phone: 111-111-1111
   address: Park Dr, Charlie Hill

 - name: Trish
   phone: 111-111-11111
   address: Small Vine, River Town

public class Persons {
  private List<Person> persons;
    .............
}

public class LoadAsJavaObjectList {

  public static void main(String[] args) throws IOException {
      Yaml yaml = new Yaml();
      try (InputStream in = LoadAsJavaObject.class.getResourceAsStream("/persons.yml")) {
          Persons persons = yaml.loadAs(in, Persons.class);
          for (Person person : persons.getPersons()) {
              System.out.println(person);
          }
      }
  }
}

Output

Person{name='Joe', phone='111-111-1111', address='Park Dr, Charlie Hill'}
Person{name='Trish', phone='111-111-11111', address='Small Vine, River Town'}

Load As Map

public class LoadAsMap {

  public static void main(String[] args) throws IOException {
      loadFromFile("/person.yml");
      loadFromFile("/persons.yml");
  }

  private static void loadFromFile(String path) throws IOException {
      System.out.printf("-- loading from %s --%n", path);
      Yaml yaml = new Yaml();
      try (InputStream in = LoadAsMap.class.getResourceAsStream(path)) {
          Iterable<Object> itr = yaml.loadAll(in);
          for (Object o : itr) {
              System.out.println("Loaded object type:" + o.getClass());
              System.out.println(o);
          }
      }
  }
}

Output

-- loading from /person.yml --
Loaded object type:class java.util.LinkedHashMap
{name=Joe, phone=111-111-11111, address=Park Dr, Charlie Hill}
-- loading from /persons.yml --
Loaded object type:class java.util.LinkedHashMap
{persons=[{name=Joe, phone=111-111-1111, address=Park Dr, Charlie Hill}, {name=Trish, phone=111-111-11111, address=Small Vine, River Town}]}

Example Project

Dependencies and Technologies Used:

• snakeyaml 1.18: YAML 1.1 parser and emitter for Java.
• JDK 1.8
• Maven 3.3.9