Cookbooks
Java
Chapter 10. Data Formats and Serialization
Working with YAML

Java:
Working with YAML

How to:

In Java, you can work with YAML files using third-party libraries since the Java Standard Edition does not include built-in support for YAML. One popular library is SnakeYAML, which allows for parsing and generating YAML data easily.

Setting up SnakeYAML

First, include SnakeYAML in your project. If you’re using Maven, add the following dependency to your pom.xml:

<dependency>
    <groupId>org.yaml</groupId>
    <artifactId>snakeyaml</artifactId>
    <version>1.30</version>
</dependency>

Reading YAML 

import org.yaml.snakeyaml.Yaml;
import java.io.InputStream;
import java.util.Map;

public class ReadYamlExample {
    public static void main(String[] args) {
        Yaml yaml = new Yaml();
        try (InputStream inputStream = ReadYamlExample.class
                .getClassLoader()
                .getResourceAsStream("config.yml")) {
            Map<String, Object> data = yaml.load(inputStream);
            System.out.println(data);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Assuming config.yml looks like this:

name: Example
version: 1.0
features:
  - login
  - signup

The output will be:

{name=Example, version=1.0, features=[login, signup]}

Writing YAML

To generate a YAML from Java objects, use the dump method provided by SnakeYAML:

import org.yaml.snakeyaml.Yaml;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.Map;

public class WriteYamlExample {
    public static void main(String[] args) {
        Map<String, Object> data = new LinkedHashMap<>();
        data.put("name", "Example");
        data.put("version", 1.0);
        data.put("features", Arrays.asList("login", "signup"));

        Yaml yaml = new Yaml();
        String output = yaml.dump(data);
        System.out.println(output);
    }
}

This will generate and print the following YAML content:

name: Example
version: 1.0
features:
- login
- signup

By leveraging SnakeYAML, Java developers can easily integrate YAML parsing and generation into their applications, benefiting from YAML’s readability and simplicity for configuration and data exchange purposes.

Working with XML