How to test if JSON object is empty in Java

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The JSON object I'm receiving looks like this:

[{"foo1":"bar1", "foo2":"bar2", "problemkey": "problemvalue"}]

What I'm trying to test for is the existence of problemvalue. If problemvalue returns a JSON Object, I'm happy. If it doesn't, it will return as {}. How do I test for this condition? I've tried several things to no avail.

This is what I've tried thus far:

//      if (obj.get("dps") == null) {  //didn't work
//      if (obj.get("dps").equals("{}")) {  //didn't work
if (obj.isNull("dps")) {  //didn't work
    System.out.println("No dps key");
}

I expected one of these lines to print "No dps key" because {"dps":{}}, but for whatever reason, it's not. I'm using org.json. The jar file is org.json-20120521.jar.

obj.length() == 0

is what I would do.

How can we check if a JSON object is empty or not in Java?, How do you check if a JSON object is empty or not? A JSON is a lightweight data-interchange format and the format of JSON is a key with value pair. The JSONObject can parse a text from a String to produce a map-like object and supports java.util.Map interface. We can check whether the JSON object is empty or not in the below example. Example

If you're okay with a hack -

obj.toString().equals("{}");

Serializing the object is expensive and moreso for large objects, but it's good to understand that JSON is transparent as a string, and therefore looking at the string representation is something you can always do to solve a problem.

Properties isEmpty() method in Java with Examples, How do you check an object is empty or not in Java? 2 Answers 2. Neither of those two things are null; they are arrays. The result is exactly what you would expect. One of your arrays is empty, the other contains a single element that is null. If you want to know if an array is empty, you would need to get the array, then check its length.

If empty array:

.size() == 0

if empty object:

.length() == 0

Handling JSON null and empty arrays and objects, . Below programs show the implementation of int isEmpty() method. Check if an object is empty in JavaScript using Object.keys in es5+: In ECMAScript 5 Object.keys() method returns an array of an object’s own property names. So to check if an object is empty or not in Javascript we can check if Object.keys().length is zero or not as shown below.

A JSON notation {} represents an empty object, meaning an object without members. This is not the same as null. Neither it is string as you are trying to compare it with string "{}". I don't know which json library are you using, but try to look for method something like:

isEmptyObject() 

Introduction to JSON-Java, This page provides Java code examples for org.json.simple. STOPPED; JSONObject state = (JSONObject) value.get("State"); if (state != null) { boolean paused  The best way to check if an object is empty is by using a utility function like the one below. So if you have an empty object, you can check whether it is empty by using the above function. Alternatively, you can write the isEmpty function on the Object prototype. Then you can easily check if the object is empty like so.

Try:

if (record.has("problemkey") && !record.isNull("problemkey")) {
    // Do something with object.
}

Java Code Examples org.json.simple.JSONObject.isEmpty, If problemvalue returns a JSON Object, I'm happy. If it doesn't, it will return as {} . How do I test for this condition? I've tried several things to no  There are two common ways of making a plain Java object candidate for JSON deserialization: including an empty constructor or using Jackson annotations. The next two examples cover those scenarios. Jackson - Deserialize to simple Java object with Empty Constructor

java: How to test if JSON object is empty in Java, How to check if JSON object is empty in Java? JSONObject myJsonObject = new JSONObject("{\"null_object_1\":[],\"null_object_2\":[null]}"); if (myJsonObject. getJSONArray("null_object_1"). length() == 0) { } How to test if a JSONObject is null or doesn't exist. not parse JSON Object!"); convenient and less ambiguous to have a NULL object than to use Java's null

How to check if JSON object is empty in Java?, With JavaScript, it can be difficult to check whether an object is empty. With Arrays, you can easily check with myArray.length, but on the other  Following is a simple example to encode a JSON object using Java JSONObject which is a subclass of java.util.HashMap. No ordering is provided. If you need the strict ordering of elements, use JSONValue.toJSONString ( map ) method with ordered map implementation such as java.util.LinkedHashMap.

How to check if JavaScript Object is empty (Example), Using JSON.stringify. If we stringify the object and the result is simply an opening and closing bracket, we know the object is empty. function  If the property in the data object is not set (unset), then the property will not appear in the JSON data. Empty property The JSON empty concept applies for arrays and objects as shown below.

Comments
  • why don't you just System.err.println(obj.get("dps"))?
  • @djechlin, thx for the suggestion. It returns "{}", but for some reason, it doesn't hit my second if statement above. =( It doesn't include any extra spaces b/c i used this line to make sure System.out.println("this is what dps is:" + obj.get("dps") + "zzz");
  • The equals() method probably isn't working because when you're printing the object out to the console, Java is calling toString() on the object to generate the value "{}". But when you're calling .equals("{}"), you're comparing some Object that's probably not a String, to a String. As a workaround, you could do: obj.get("dps").toString().equals("{}"), but it is a hackish solution at best.
  • I suspect what it's returning is not the characters "{}" but an empty "object".
  • @CraigOtis i used your solution and since you were the first one to post it, i'll vote for ur soln if you make it an answer.
  • thx for your suggestion. i'm using org.json (jar file org.json-20120521.jar). it doesn't look like there's a method called isEmptyObject. =(
  • @Classified I am not familiar with org.json so this might not be the optimum way. An empty object has no member so therefore method keys() should return iterator with length zero. getJSONObject("problemkey").keys() - check the length of that.
  • which library do you use? I found org.json via a google search so I don't know how good/bad it is but it looked fairly popular. json.org/javadoc/org/json/JSONObject.html. thx again for your responses and help
  • At the moment Jackson. But this does not mean that org.json is bad, just different.
  • Another workaround would be to convert your problem value to JSON string and compare it with string "{}". Something like obj.get("dps").toString().equals("{}"). But check what does toString actualy return regarding to whitespaces.
  • thx for the suggestion. when I tried your code, it thinks {} is not null and prints my message, which is not what i want. i dont' know why it thinks {} is not null.
  • This is actually pretty clever. I wouldn't use it on something so small as this, but it's definitely not an empty-check I had thought of before.
  • Please look at How do I format my Code blocks? and then add some explanation to your answer.
  • thx for the suggestion. I checked and there are no extra spaces. =(
  • How would the cast go?