getJSON vs. optJSON

Question

I was looking over the documentation for JSONObject when I noticed the two methods: getJSONObject(String key) and optJSONObject(String key). From the documentation, I figured they did nearly the same thing with one difference: If the key or value isn't found, then getJSONObject() throws a JSONException whereas optJSONObject() simply returns null.

1. Are there any other differences between getJSONObject() and optJSONObject()?
2. What are the advantages of get over opt and vice-versa?
3. Are there specific situations where I would want to use one over the other or where the use of one is strongly discouraged/prohibited?

Answer 1

A value in the JSON may be optional, so using optJSONObject is better because you just have to check if it is null or not and continue your function.

Answer 2

optString returns the empty string ("") if the key you specify doesn't exist. getString throws a JSONException.

Answer 3

1. Yes. getJSONObject() throws an exception when that object is not found. optJSONObject() returns null.
2. Honestly there aren't really any advantages to one over the other, it's really a matter of personal preference.
3. Only reason I can think of is for readability potentionally. For instance see how this code accomplishes the same thing

This option is a bit easier to read if you are doing a lot more when the object isn't present.

JSONObject object = jsonResponse.optJSONObject("object");

if(object == null)
{
    // handle not existing here
}

This option is a bit easier if you are only throwing another exception or doing something else that's one line.

JSONObject object = null;    

try
{
    object = jsonResponse.getJSONObject("object");
}
catch(JSONException je)
{
    // handle object not found here
}