Convert JSON to YAML in Java [Complete Guide]

Method 1: Using Jackson (Recommended)

Jackson is the most popular JSON library for Java and supports YAML through the jackson-dataformat-yaml module. It's the recommended approach for most Java projects, especially those using Spring Boot. Prefer a different language? See our Python, JavaScript, or Go guides.

Step 1: Add Maven Dependencies

<!-- pom.xml -->
<dependencies>
    <!-- Jackson Core -->
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.16.1</version>
    </dependency>
    
    <!-- Jackson YAML Support -->
    <dependency>
        <groupId>com.fasterxml.jackson.dataformat</groupId>
        <artifactId>jackson-dataformat-yaml</artifactId>
        <version>2.16.1</version>
    </dependency>
</dependencies>

Step 2: Convert JSON to YAML

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;

public class JsonToYamlConverter {
    
    public static String convertJsonToYaml(String jsonString) throws Exception {
        // Parse JSON
        ObjectMapper jsonMapper = new ObjectMapper();
        Object jsonObject = jsonMapper.readValue(jsonString, Object.class);
        
        // Convert to YAML
        YAMLMapper yamlMapper = new YAMLMapper();
        return yamlMapper.writeValueAsString(jsonObject);
    }
    
    public static void main(String[] args) throws Exception {
        String json = """
            {
                "name": "My App",
                "version": "1.0.0",
                "database": {
                    "host": "localhost",
                    "port": 5432
                }
            }
            """;
        
        String yaml = convertJsonToYaml(json);
        System.out.println(yaml);
    }
}

Output:

---
name: "My App"
version: "1.0.0"
database:
  host: "localhost"
  port: 5432

Method 2: Using SnakeYAML

SnakeYAML is a lightweight YAML library. Use it with a JSON library like Gson or org.json for JSON to YAML conversion.

Maven Dependencies

<dependencies>
    <!-- SnakeYAML -->
    <dependency>
        <groupId>org.yaml</groupId>
        <artifactId>snakeyaml</artifactId>
        <version>2.2</version>
    </dependency>
    
    <!-- Gson for JSON parsing -->
    <dependency>
        <groupId>com.google.code.gson</groupId>
        <artifactId>gson</artifactId>
        <version>2.10.1</version>
    </dependency>
</dependencies>

Convert JSON to YAML with SnakeYAML

import com.google.gson.Gson;
import org.yaml.snakeyaml.DumperOptions;
import org.yaml.snakeyaml.Yaml;
import java.util.Map;

public class JsonToYamlSnakeYAML {
    
    public static String convertJsonToYaml(String jsonString) {
        // Parse JSON with Gson
        Gson gson = new Gson();
        Map<String, Object> data = gson.fromJson(jsonString, Map.class);
        
        // Configure YAML output
        DumperOptions options = new DumperOptions();
        options.setDefaultFlowStyle(DumperOptions.FlowStyle.BLOCK);
        options.setPrettyFlow(true);
        options.setIndent(2);
        
        // Convert to YAML
        Yaml yaml = new Yaml(options);
        return yaml.dump(data);
    }
    
    public static void main(String[] args) {
        String json = "{\"name\":\"Test\",\"enabled\":true,\"count\":42}";
        String yaml = convertJsonToYaml(json);
        System.out.println(yaml);
    }
}

Convert YAML to JSON in Java

Reverse the process to convert YAML to JSON in Java:

Jackson: YAML to JSON

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;

public class YamlToJsonConverter {
    
    public static String convertYamlToJson(String yamlString) throws Exception {
        // Parse YAML
        YAMLMapper yamlMapper = new YAMLMapper();
        Object yamlObject = yamlMapper.readValue(yamlString, Object.class);
        
        // Convert to JSON
        ObjectMapper jsonMapper = new ObjectMapper();
        return jsonMapper.writerWithDefaultPrettyPrinter()
                         .writeValueAsString(yamlObject);
    }
}

SnakeYAML: YAML to JSON

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import org.yaml.snakeyaml.Yaml;
import java.util.Map;

public class YamlToJsonSnakeYAML {
    
    public static String convertYamlToJson(String yamlString) {
        // Parse YAML
        Yaml yaml = new Yaml();
        Map<String, Object> data = yaml.load(yamlString);
        
        // Convert to JSON
        Gson gson = new GsonBuilder().setPrettyPrinting().create();
        return gson.toJson(data);
    }
}

Spring Boot Integration

Spring Boot uses Jackson by default. Add the YAML dependency and create a converter service. For quick conversions without writing Java code, try our online JSON to YAML converter.

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLMapper;
import org.springframework.stereotype.Service;

@Service
public class ConversionService {
    
    private final ObjectMapper jsonMapper;
    private final YAMLMapper yamlMapper;
    
    public ConversionService() {
        this.jsonMapper = new ObjectMapper();
        this.yamlMapper = new YAMLMapper();
    }
    
    public String jsonToYaml(String json) throws Exception {
        Object data = jsonMapper.readValue(json, Object.class);
        return yamlMapper.writeValueAsString(data);
    }
    
    public String yamlToJson(String yaml) throws Exception {
        Object data = yamlMapper.readValue(yaml, Object.class);
        return jsonMapper.writerWithDefaultPrettyPrinter()
                         .writeValueAsString(data);
    }
}

Jackson vs SnakeYAML Comparison

Error Handling

Always wrap conversion in try-catch blocks:

public String safeJsonToYaml(String json) {
    try {
        ObjectMapper jsonMapper = new ObjectMapper();
        YAMLMapper yamlMapper = new YAMLMapper();
        Object data = jsonMapper.readValue(json, Object.class);
        return yamlMapper.writeValueAsString(data);
    } catch (JsonProcessingException e) {
        throw new IllegalArgumentException("Invalid JSON: " + e.getMessage(), e);
    } catch (Exception e) {
        throw new RuntimeException("Conversion failed: " + e.getMessage(), e);
    }
}