how to convert json into pojo where no param name is given

Kapil Sharma :

I am trying to convert JSON to java using Jackson. But not getting proper solution. I have JSON which does not have parameter name in it. I want to use PropertyOrder to map json fields to POJO.

I tried type reference in all possible ways but failed to get my desired result.

My JSON is like : {"1222": ["Joe", 26, 158],"1232": ["root", 29, 168] }

Below are the pojo:

public class Employee{
    int empId;
    EmployeeAtttribute employeeAttribute;
}

@JsonProertyOrder({"name", "seq", "height"})  
public class EmployeeAttribute{     
    String name;  
    int seq;  
    int height;  
}  

I am looking to get List of Employee class made using JSON.

Thanks in Advance.

TechFree :

Annotate EmployeeAttribute class as:

@JsonFormat(shape = JsonFormat.Shape.ARRAY)
@JsonPropertyOrder({"name", "seq", "height"})
public class EmployeeAttribute
{

    public String name;

    public int seq;

    public int height;

    @Override
    public String toString()
    {
        return "EmployeeAttribute [name=" + name + ", seq=" + seq + ", height=" + height + "]";
    }
}

You can use this code to convert your JSON to Object (map):

ObjectMapper mapper = new ObjectMapper();
String jsonInput = "{\"1222\": [\"Joe\", 26, 158],\"1232\": [\"root\", 29, 168] }";
TypeReference<Map<String, EmployeeAttribute>> typeRef =
    new TypeReference<Map<String, EmployeeAttribute>>()
    {
    };

Map<String, EmployeeAttribute> map = mapper.readValue(jsonInput, typeRef);
map.values().iterator().forEachRemaining(System.out::println);

Further convert this to a list of Employee:

 List<Employee> employee = new ArrayList<>();
 for (Map.Entry<String, EmployeeAttribute> entry : map.entrySet()) {
       employee.add(new Employee(Integer.valueOf(entry.getKey()), 
  entry.getValue()));
 }

To the extended requirement where the input JSON string contained 'emp_count' key, since the input is not really parseable to a Java Object model, this approach can be used which reads this element, and removes it, so that parsing as per the original logic would work as before and the 'emp_count' is still read/extracted. Optimize as required:

String jsonInput = "{\"1222\": [\"Joe\", 26, 158],\"1232\": [\"root\", 29, 168], \"emp_count\" : \"2\"}";
JsonNode node = mapper.readTree(jsonInput);
if (node.has("emp_count")) {
   int employeesInArray = ((ObjectNode) node).remove("emp_count").asInt();
   System.out.println("Num of employees in array: " + employeesInArray);
} else {
   System.out.println("Num of employees was not provided, missing emp_count element");
}

//updated JSON input String, that works as before
jsonInput = node.toString();