Java constructor should use setter?

I have a simple Java model Class called Person which have a constructor that receives a JSONObject. In that constructor I get the values from the JSONObject and put in my instance variables. This is just a simple question but which way is best?

public Person(JSONObject personJsonObject) {
    // Without setter
    this.name = personJsonObject.getString("name");
    // With setter passing String
    setName(personJsonObject.getString("name"));
    // With setter passing JSONObject
    setName(personJsonObject);
}

And when my setter isn't just a simple attribution but a evaluation, which one should I use?

public Person(JSONObject personJsonObject) {
    // Without setter
    this.fullName = personJsonObject.getString("name") + personJsonObject.getString("lastName");
    // With setter passing String
    setFullName(personJsonObject.getString("name"), personJsonObject.getString("lastName"));
    // With setter passing JSONObject
    setFullName(personJsonObject);
    // Or should I put this logic in the getFullName method? The caveat is if there is a huge calculation in the getter method. It wouldn't be efficient.
}

Thanks for your answer.