Convert String into json array object...android

Question

I get from the server array of objects, and by this code I convert it to json:

public static ArrayList<bussListCubic> parseBussinessArray(String result) {
 ArrayList<bussListCubic> arr = new ArrayList<bussListCubic>();
 try {
 JSONArray jArray = new JSONArray(result);
 JSONObject json_data = null;
 for (int i = 0; i < jArray.length(); i++) {
 json_data = jArray.getJSONObject(i);
 bussListCubic userInfo = parseBussListCubic(json_data);
 arr.add(userInfo);
 }
 } catch (JSONException e) {
 // TODO Auto-generated catch block
 e.printStackTrace();
}
return arr;

}

Some times the app crashed and this is the error:

Caused by: java.lang.NullPointerException at
org.json.JSONTokener.nextCleanInternal(JSONTokener.java:116) at
org.json.JSONTokener.nextValue(JSONTokener.java:94) at
org.json.JSONArray.<init>(JSONArray.java:87) at
org.json.JSONArray.<init>(JSONArray.java:103)

it is also point that the error with this line : JSONArray jArray = new JSONArray(result): line #4 in the above code...what does this error mean ?

thank you

• keyser: The error is the most common error there is. It means that something is null, and you're trying to use that object as if it wasn't.
• user3516596: ok, But how you explain that the app most of the time work perfect, and sometimes it crashed !!
• user2323471: Please Check the json before looping it. Check it if it contain data then only use it.
• keyser: Because sometimes it's null, and sometimes it isn't. There's nothing magic going on :p
• user3516596: so How could I check if the result contain data !!!

Answer 1

The crash is caused by an invalid String result

print the result passed to parseBussinessArray method and see what is its value when crash happens

• user3516596: actually I also try to send wrong result data"Just for test it", and the app doesn't crash, it just doesn't display anything!!!
• Silverstorm: If you use a try catch the error is masked, for this reason the app doesn't crash but doesn't show the values, with wrong input
• user3516596: actually now i just try to send null result to parseBussinessArray and I got the same error, so some times the app send null result !!
• Silverstorm: I don't know the way you pass result to this method but surely the issue is before, and when result is null cause this problem. You should manage the problem before invoking parseBussinessArray, adding the appropriate checks