Yaml2Properties.java

package org.example;

import org.yaml.snakeyaml.Yaml;

import java.util.*;
import java.util.stream.IntStream;
import java.util.stream.Stream;

public class Yaml2Properties {

    private static Stream<Map.Entry<String, String>> processEntry(String prefix, Object o) {
        if (o instanceof ArrayList) {
            ArrayList list = (ArrayList) o;
            return IntStream.range(0, list.size())
                    .boxed()
                    .flatMap(i -> processEntry(prefix + "." + i, list.get(i)));
        } else if (o instanceof Map) {
            Map<String, ?> map = (Map) o;
            return map.entrySet()
                    .stream()
                    .flatMap(entry -> processEntry(prefix + "." + entry.getKey(), entry.getValue()));
        } else {
            String value = String.valueOf(o);
            return Stream.of(new AbstractMap.SimpleEntry<>(prefix, value));
        }
    }

    public static Properties yaml2props(Map<String, ?> map) {
        Stream<Map.Entry<String, String>> stream = map.entrySet()
                .stream()
                .flatMap(entry -> processEntry(entry.getKey(), entry.getValue()));
        Properties result = new Properties();
        stream.forEach(entry -> result.setProperty(entry.getKey(), entry.getValue()));
        return result;
    }

    public static void main(String[] args) {
        Yaml yaml = new Yaml();
        Map<String, ?> map = yaml.load(Yaml2Properties.class.getResourceAsStream("/test.yaml"));

        Properties props = yaml2props(map);
        props.list(System.out);

    }
}