Check if JSON node is null

Question

I'm returning some JSON from an api, and one of the child nodes of the root object is item.

I want to check whether this value at this node is null. Here's what I'm trying, which is currently throwing a JSONException when the node actually is null:

if (response.getJSONObject("item") != null) {

// do some things with the item node

} else {

// do something else

}

Logcat

07-22 19:26:00.500: W/System.err(1237): org.json.JSONException: Value null at item of type org.json.JSONObject$1 cannot be converted to JSONObject

Note that the this item node isn't just a string value, but a child object. Thank you in advance!

Snoi Singla · Accepted Answer · 2020-07-16 06:47:53Z

10

To do a proper null check of a JsonNode field:

JsonNode jsonNode = response.get("item");

if(jsonNode == null || jsonNode.isNull()) { }

The item is either not present in response, or explicitly set to null .

answered Jul 16, 2020 at 6:47

Snoi Singla

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Comments

Nebu · Accepted Answer · 2014-07-22 23:57:46Z

8

OK, so if the node always exists, you can check for null using the .isNull() method.

if (!response.isNull("item")) {

// do some things with the item node

} else {

// do something else

}

answered Jul 22, 2014 at 23:57

Nebu

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2 Comments

Sky Kelsey Over a year ago

This is the correct answer. I wish they never included the has() method.

Anderson K Over a year ago

The method has("tag") is important for scenarios in which for one reason som expected "tag" is not returned(request from RestFull), by this method we can avoid exceptions!!!!

Dawid Czerwinski · Accepted Answer · 2014-07-23 00:35:55Z

1

I am assuming that your response is from httpClient right? If so, you can just check the length of it.

HttpResponse response = httpclient.execute(httppost);
String responseBody = EntityUtils.toString(response.getEntity());

String.valueOf(responseBody.length())

If you are getting anything should be greater than 0 I suppose :)

answered Jul 23, 2014 at 0:35

Dawid Czerwinski

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Comments

Anderson K · Accepted Answer · 2014-07-22 23:51:56Z

-2

First you can check if the key exists, using method has("");

if(response.has("item")) {

    if (response.getJSONObject("item") != null) {

        // do some things with the item node

    } else {

        // do something else

    }
}

edited Jul 22, 2014 at 23:51

answered Jul 22, 2014 at 23:46

Anderson K

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3 Comments

settheline Over a year ago

I'm afraid that won't work, because the response always returns the "item" node, but it looks like this "item":null sometimes. Hence, it would bypass the first if statement and then throw the exception at the second if statement.

Anderson K Over a year ago

An exception will be thrown without you perform this call response.getJSONObject ("Item"), and the key 'item' does not exist!

settheline Over a year ago

Sorry, I don't understand the meaning of your last comment. The key item will always be present in the Json Object. It's just a matter of whether the value is real data or null.

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