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Check if object exists in JSON

I need to know if an object exists in a JSON string and do different things depending on the existence of that object. If it doesn't exist, I want to omit the object because it throws a NullPonterException. I tried using if but no time ... Can anyone tell me how I can check for the existence of an object?

Thank you in advance!

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4 answers


Try the following:



String jsonString = yourJsonString;
String nameOfObjectInQuestion = "yourObjectInQuestion";
JSONObject json = null;
JSONObject objectInQuestion = null;
try { 
    json = new JSONObject(jsonString); 
    objectInQuestion = json.getJSONObject(nameOfObjectInQuestion);
} 
catch (JSONException ignored) {}

if (objectInQuestion == null) {
    // Stomp your feet
}
else {
    // Clap your hands
}
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You can use isNull () function in JSONObjects.

"boolean isNull (string name) Returns true if this object has no mapping for name or has a mapping that is NULL."



JSONObject contact = venueitem.getJSONObject("contact");

if (contact.isNull("formattedPhone") == false)
    venue.phone = contact.getString("formattedPhone");
else
    {
    ...
    }

Source: http://developer.android.com/reference/org/json/JSONObject.html#isNull(java.lang.String)

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Use JSONObject.has (String).

 JSONObject MyObject = null;
 if(JSONObject.has("ObjectName")){
        MyObject = JSONObject.getJSONObject("ObjectName");
 }

 if(MyObject != null){
  // do stuff
 }

http://developer.android.com/reference/org/json/JSONObject.html#has(java.lang.String)

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Or .. more concise ...

myJSONObject.isNull("myfield")?"":myJSONObject.getString("myfield")
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