How to compare null value from the JsonObject in java

For com.google.gson.JsonObject, I followed this :

boolean isIdNull = jsonObject.get("Id").isJsonNull();

In my json, I have :

"Id":null

if(jsonObject.isNull("parentId")){
    jsonObject.put("parentId", 0);
}

Use the following method of JsonObject to check if a value against any key is null

public boolean isNull(java.lang.String key)

This method is used to check Null against any key or if there is no value for the key.

check this in the documentation

Your Modified code should be like this

if(jsonObject.isNull("parentId"))
    {
        System.out.println("inside null");
        jsonObject.put("parentId", 0);
    }
    else
    {
        System.out.println("inside else part");
        //jsonObject.put("parentId", jsonObject.getInt("parentId"));
        jsonObject.put("parentId", 0);
    }