Java exception handling (example with json)

Question

First, I would like to say I'm sorry for such an ambiguous title...

I would like to know how to handle exceptions in the following scenario... I have a Struts action that receives a string from a EJB:

try{       
  JSONObject data = new JSONObject(result);   //result is String 
  String gatewayId = data.getString("gatewayId");
  session.setAttribute("gatewayId", gatewayId);
}catch(Exception e){
  System.out.println(e.getMessage());
}

EDIT Imports are:

import org.apache.struts2.json.*;
import org.json.*;

In case A json is:

{"gatewayId":100, "mask":4}

In case B json is:

{"success":false, "errorDesc":"bla bla"}

If the gatewayId is in the JSON I have no problem, but the problem is that the JSON received from EJB can (but doesn't have to) have that key:value pair.

If there was a Boolean JsonObject.hasString() method I would have no exceptions thanks to checking the existance of the string first in if/else if statements, but this way I can't avoid exceptions...

The first thing I thought I could do was to have different catch blocks depending on the exception type, but it seems that all exceptions are of generic JSONException type and also I shouldn't put any JSON treating code in the catch block because that code could also be throwing it's exceptions.

Please, have in mind that I'm not looking for the exact solution of my JSON problem here, but rather a general explanation of how to solve this kind of problems when you don't have functions that help you avoid having exceptions...

I hope my question makes sense....

before putting into json object, could you display result and let me know what you have?? — Fahim Parkar
– Fahim Parkar, Commented Jun 11, 2012 at 10:37
Luigi, for completeness pls include the import statement that allows you to refer to JSONObject. Also it would be useful to have a simplified sample of the JSON string that you are processing. — Rob Kielty
– Rob Kielty, Commented Jun 11, 2012 at 10:58

Pankaj Singhal · Accepted Answer · 2012-06-11 10:30:36Z

3

try

data.has("gatewayId");

this would help.

answered Jun 11, 2012 at 10:30

Pankaj Singhal

16.2k9 gold badges52 silver badges88 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

luigi7up Over a year ago

Pankraj, thanks... that would be the solution of this concrete problem, but imagine that the library had no data.has() method. I know that would be a bad library then :) Exception would be thrown if json key is not found... Basically the question is could you be using catch blocks as a flow control? somehow? :)

Collectives™ on Stack Overflow

Java exception handling (example with json)

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related