java - Jackson throws JsonMappingException on deserialize; demands single-String constructor?

Question

Another question, but it relates to this one: Deserializing JSON with Jackson - Why JsonMappingException "No suitable constructor"?

This time I am getting a different error, namely that the Jackson deserializer complains that I do not have a "single-String constructor/factory method" in my class ProtocolContainer.

However, if I add a single-String constructor, like this:

public ProtocolContainer(String json) {}

the exception does indeed disappear, but the ProtocolContainer that I expected to be there is all "empty", i.e. all its properties are in their initial state, and not populated according to the JSON-string.

Why is that?

I'm pretty sure you shouldn't need a single-String constructor, and if you do that you should not have to populate the properties in that constructor, right?

=)

Answer 1

Oh, so once again I found out the answer AFTER I posted this question (even though I tried a lot of things before posting).

What I did to solve this was to use the @JsonCreator annotation. I simply annotated my static Create method, like this:

@JsonCreator
public static ProtocolContainer Create(String jsonString)
{

    ProtocolContainer pc = null;
    try {
        pc = mapper.readValue(jsonString, ProtocolContainer.class);
    } catch (JsonParseException|JsonMappingException|IOException e) {
        // handle
    }

    return pc;
}

And then problem solved.