check value exist or not in JSON object to avoid JSON exception

Question

I am getting a JSONObject from a webservice call.

JSONObject result = ...........

When i am accessing like result.getString("fieldName");

If the fieldName exist in that JSONObject then it is working fine.If that is not exist i am getting exception JSONObject["fieldName"] not found.

I can use try catch for this.But i have nearly 20 fields like this.Am i need to use 20 try catch blocks for this or is there any alternative for this.Thanks in advance...

Answer 1

There is a method JSONObject#has(key) meant for exactly this purpose. This way you can avoid the exception handling for each field.

if(result.has("fieldName")) {
    // It exists, do your stuff
} else {
    // It doesn't exist, do nothing 
}

Also, you can use the JSONObject#isNull(str) method to check if it is null or not.

if(result.isNull("fieldName")) {
    // It doesn't exist, do nothing
} else {
    // It exists, do your stuff
}

You can also move the logic to a common method (for code reusability), where you can pass any JSONObject & the field name and the method will return if the field is present or not.