在Java for Android中解析JSON数据

Question

I hope someone might be able to help me. I am trying to parse following json file:

{"seminar":[
    {"categoryid": "1","cpe": "13","inventory":["Discussion","Value x","Value y"
    ],"teachers": [
    {
        "titel": "Dipl.-Ing.",
        "company": "XY",
        "name": "Test",
        "id": "3",
    }
    ],

},...

I am lost with parsing the teachers data in...

...
private static final String TAG_teachers = "teachers";
private static final String TAG_TITLE = "title";

for(int i = 0; i < seminar.length(); i++){
    JSONObject c = seminar.getJSONObject(i);
    ...
    teachers = c.getJSONArray(TAG_DOZENTEN);
    for(int z = 0; z < teachers.length(); z++){                 
    JSONObject d = teachers.getJSONObject(z);
    String title  = d.getString(TAG_TITLE);
    Log.d("JSONParsingActivity", title);

I get the error System.err(1010): org.json.JSONException: Value null at teachers of type org.json.JSONObject$1 cannot be converted to JSONArray.

What did I do wrong? As I understand from the JSON documentation, teachers is an JSON Array and not an Object. Is somebody able to help me?

Answer 1

You have an extra (trailing) comma in teachers (after "3"). Not allowed in JSON. Remove it and see if that helps.

Answer 2

If your JSON is really of the form:

{ ... }, { ... }, { ... }, ...

This is invalid JSON

The root enclosure must either be a single object (in {} ) or an array (in [] ).

If your intent is to send an array of objects, then simply wrap the entire thing with square brackets to make it an array and create a JSONArray object from it.

So it must be like this

[ { ... }, { ... }, { ... }, ... ]

You also need to make sure that you don;t have extra commas, unclosed brackets, etc. Use JSONLint or other similar JSON format checker to save yourself some time in finding syntax problems.