YAML for Java. A user-friendly OOP library.
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YAML for Java. A user-friendly OOP library. Based on spec 1.2.

From the specification: YAML™ is a human-friendly, cross language, Unicode based data serialization language.

To get the latest release, simply add the following to your pom.xml:


or download the fat jar.


The API of this library is clean, intuitive and generally close to the javax.json API that most developers are used to:


Since the library is quite young, it doesn't support all the features of YAML yet. For now, it only supports creating/parsing Block Style YAML, so use it if you have to read/create configuration files and such stuff. It doesn't yet implement features such as flow or recursive representation, aliases & anchors or document streams (more YAMLs separated by ---).

However, keep in mind that the library is based on interfaces and OOP best practices, so you can probably extend/decorate the objects in order to create the functionality you need!

If you have some time and like the library, please consider contributing.

Building and printing Yaml:

YamlMapping yaml = Yaml.createYamlMappingBuilder()
    .add("architect", "amihaiemil")

toString() methods are overriden to pretty-print the yaml, so the above yaml.toString() will print:

architect: amihaiemil
  - amihaiemil
  - salikjan
  - SherifWally
  - rultor
  - 0pdd


Reading a Yaml input is very straight-forward, as outlined bellow. There is one important aspect: the input has to be a valid (well-indented) Yaml, otherwise you will get an exception, at some point, when trying to work with the read object!

//createYamlInput is overloaded to accept also String InputStream
YamlMapping yamlMapping = Yaml.createYamlInput(new File("mapping.yml"))

YamlSequence yamlSequence = Yaml.createYamlInput(new File("sequence.yml"))

Parsing a Pojo:

Pojos can be parsed ("dumped") into Yaml as follows (attributes need to have getters and setters):

Map<String, Integer> grades = new HashMap<>();
grades.put("Math", 9);
grades.put("CS", 10);
YamlMapping studentYaml = new YamlObjectDump(
    new Student ("John", "Doe", 20, grades)

studentYaml.toString() will print:

age: 20
firstName: John
  CS: 10
  Math: 9
lastName: Doe

You can also parse maps (Map<Object, Object>) and collections (Collection<Object>) using YamlMapDump and YamlCollectionDump respecitvely


Contributors are welcome

  1. Open an issue regarding an improvement you thought of, or a bug you noticed, or ask to be assigned to an existing one.
  2. If the issue is confirmed, fork the repository, do the changes on a separate branch and make a Pull Request.
  3. After review and acceptance, the PR is merged and closed.
  4. You are automatically listed as a contributor on the repo and the project's site (to follow)

Make sure the maven build

$ mvn clean install -Pcheckstyle

passes before making a PR.