Parsing Yaml in Java

Question

I have the following YAML I want to parse using Jackson parser in Java.

android:
    "7.0":
        - nexus
        - S8
    "6.0":
        - s7
        - g5
ios:
    "10.0":
        - iphone 7
        - iphone 8

I created a created class which has getter and setter as Java Object for android. It works fine. But how do I do the same for 6.0 and 7.0? I'm usingJackson` Parser

Answer 1

No idea whether Jackson supports that; here's a solution with plain SnakeYaml (I will never understand why people use Jackson for parsing YAML when all it does is basically take away the detailed configuration possible with SnakeYaml which it uses as backend):

class AndroidValues {
     // showing what needs to be done for "7.0". "8.0" works similarly.
     private List<String> v7_0;

     public List<String> getValuesFor7_0() {
         return v7_0;
     }

     public void setValuesFor7_0(List<String> value) {
         v7_0 = value;
     }
}

// ... in your loading code:

Constructor constructor = new Constructor(YourRoot.class);
TypeDescription androidDesc = new TypeDescription(AndroidValues.class);
androidDesc.substituteProperty("7.0", List.class, "getValuesFor7_0", "setValuesFor7_0");
androidDesc.putListPropertyType("7.0", String.class);
constructor.addTypeDescription(androidDesc);
Yaml yaml = new Yaml(constructor);

// and then load the root type with it

Note: Code has not been tested.

Answer 2

I think that you should try annotation com.fasterxml.jackson.annotation.JsonProperty. I'll provide a short example below.

Sample YAML file:

---
"42": "some value"

Data transfer object class:

public class Entity {

    @JsonProperty("42")
    private String value;

    public String getValue() {
        return value;
    }

    public void setValue(String value) {
        this.value = value;
    }

}

Parser:

public class Parser {

    public static void main(String[] args) throws IOException {
        ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
        Entity entity = mapper.readValue(new File("src/main/resources/sample.yml"), Entity.class);
        System.out.println(entity.getValue());
    }

}

The console output should be: some value.

P.S. I tested it with the following dependencies:

    <dependency>
        <groupId>com.fasterxml.jackson.dataformat</groupId>
        <artifactId>jackson-dataformat-yaml</artifactId>
        <version>2.3.0</version>
    </dependency>
    <dependency>
        <groupId>com.fasterxml.jackson.core</groupId>
        <artifactId>jackson-databind</artifactId>
        <version>2.2.3</version>
    </dependency>