How to check "isEmpty()" in Gson JsonObject?

You can use JsonObject#entrySet() to get the JSON object's set of name/value pairs (its members). That returns a Set which has the traditional isEmpty() method you're looking for.

For example,

JsonObject jsonObject = ...;
Set<Map.Entry<String,JsonElement>> members = jsonObject.entrySet();
if (members.isEmpty()) {
    // do something
}

Its more correct to use the Set.isEmpty() for this purpose

if (jsonObject.entrySet().isEmpty()) {

}