Why can't I unwrap the root node and deserialize an array of objects?

Question

Why am I not able to deserialize an array of objects by unwrapping the root node?

import java.io.IOException;
import java.util.Arrays;
import java.util.List         


        

Answer 1

This code worked for me:

import org.codehaus.jackson.map.ObjectMapper;
import org.junit.Assert;
import org.junit.Test;

import java.io.IOException;
import java.util.List;

public class RootNodeTest extends Assert {

public static class CustomerMapping {
    public List customer;

    public List getCustomer() {
        return customer;
    }

    public static class Customer {
        public String email;

        public String getEmail() {
            return email;
        }
    }

}

@Test
public void testUnwrapping() throws IOException {
    String json = "{\"customer\":[{\"email\":\"hello@world.com\"},{\"email\":\"john.doe@example.com\"}]}";
    ObjectMapper mapper = new ObjectMapper();
    CustomerMapping customerMapping = mapper.readValue(json, CustomerMapping.class);
    List customers = customerMapping.getCustomer();
    for (CustomerMapping.Customer customer : customers) {
        System.out.println(customer.getEmail());
    }
  }
}

First of all you need a java object for the whole json object. In my case this is CustomerMapping. Then you need a java object for your customer key. In my case this is the inner class CustomerMapping.Customer. Because customer is a json array you need a list of CustomerMapping.Customer objects. Also, you do not need to map the json array to a java array and convert it then to a list. Jackson already does it for you. Finally, you just specify the variable email of type String and print it to the console.