getJSON vs. optJSON

问题

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?

回答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.

回答2:

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

回答3:

I'm using optJSONObject to my json file with key "sentences" and it return null but the correct result might JSONArray or String.

{
"sentences":[
  {
     "trans":"làm",
     "orig":"do",
     "translit":"",
     "src_translit":""
  }
]
}

来源：https://stackoverflow.com/questions/11316152/getjson-vs-optjson