如何将2d json数组映射到pojo类？

Question

I have a json structre as below

{
"components":
{
"metadata":[
   [
     {"component":2},{"component":9}
   ],
   [
     {"component":10},{"component":15}
   ]
 ]
}
}

And my POJO class is ()

public class Components {

private List<Metadata> metadata;
// Getters and setters
}

public class Metadata{  

private List<String> component;
// Getters and setters

}

I am getting error in ObjectMapper as below:

"Can not deserialize instance of com.sections.metadata.Metadata out of START_ARRAY token"

Can anyone help me correcting my POJO class structure ? Since the json is a 2D array, I have created two arrayLists, one in Component class and other in Metadata class.

Thanks in advance !

Answer 1

{
"components":
{
  "metadata":[
    [
      {"component":2},{"component":9}
    ],
    [
      {"component":10},{"component":15}
    ]
  ]
}
}

---

The above JSON doesnot correspond to the object structure that you specified.

• In the components, there is no Array of 'metadata'. Note that there are no '[]' around it.
• Inside metadata, there is an array of objects(or simply arrays) each of which has List of Strings, component

Answer 2

This is what you need:

public class ComponentsWrapper {

    private Components components;

    public Components getComponents() {
        return components;
    }

    public void setComponents(Components components) {
        this.components = components;
    }

    public static void main(String[] args) throws IOException, URISyntaxException {
        ObjectMapper objectMapper = new ObjectMapper();
        ComponentsWrapper components =
                objectMapper.readValue(<your JSON>),
                        ComponentsWrapper.class);


    }
}

class Components {

    private List<List<Component>> metadata;

    public List<List<Component>> getMetadata() {
        return metadata;
    }

    public void setMetadata(List<List<Component>> metadata) {
        this.metadata = metadata;
    }
}

class Component {

    private int component;

    public int getComponent() {
        return component;
    }

    public void setComponent(int component) {
        this.component = component;
    }
}