JsonHelper

This is a helper class for Javas GSON based JSON class.

Introduction

Dealing with JSON on Java is often a very complicated task. The google project GSON comes in very handy but needs a lot of additional validation checking when dealing with remote content.

For example:

{
  "dogs": [
    {
      "name": "Rex",
      "breed": "German shepherd"
    },
    {
      "name": "Fifi",
      "breed": "Boxer"
    }
  ]
}

Lets print all dog names with their breeds:

try {
  JsonElement json = new JsonParser().parse(jsonContent);
  
  if (json.isJsonObject() && json.getAsJsonObject().has("dogs") && json.getAsJsonObject().get("dogs").isJsonArray()) {
    JsonArray dogs = json.getAsJsonObject().getAsJsonArray("dogs");
    for (final JsonElement dog : dogs) {
      String name;
      String breed;
      
      if (dog.isJsonObject() && dog.getAsJsonObject().has("name") && dog.getAsJsonObject().get("name").isJsonPrimitive()  && dog.getAsJsonObject().getAsJsonPrimitive("name").isString()) {
        name = dog.getAsJsonObject().getAsJsonPrimitive("name").getAsString();
      }
      
      if (dog.isJsonObject() && dog.getAsJsonObject().has("breed") && dog.getAsJsonObject().get("breed").isJsonPrimitive()  && dog.getAsJsonObject().getAsJsonPrimitive("breed").isString()) {
        breed = dog.getAsJsonObject().getAsJsonPrimitive("breed").getAsString();
      }
      
      if (name != null && breed != null) {
        System.out.println("Name: " + name + " Breed: " + breed);
      }
    }
  }
}
catch (Exception e) {
  // handle exeptions...
}

As you can can see this is very complicated and not very readable. With my JsonHelper class the same code can be executed in a way more elegant way:

JsonHelper json = new JsonHelper(jsonContent);

for (JsonHelper dog: json.get("dogs")) {
  String name = dog.get("name").stringValue();
  String breed = dog.get("breed").stringValue();
  
  if (name != null && breed != null) {
    System.out.println("Name: " + name + " Breed: " + breed);
  }
}

Additionally you can use the basic iterator pattern in order to iterate over JsonObjects and a toString method which returns a JSON string:

JsonHelper json = new JsonHelper(jsonContent);

for (Map.Entry<String, JsonHelper> element: json.entrySet()) {
  System.out.println("Key: " + element.getKey() + " Value: " + element.getValue());
}

System.out.println(json.toString()); // => "{ \"dogs\": ...
System.out.println(json.get("dogs").get(0).get("name").toString()); // => Rex

The cool thing is that you don't need to worry about non existing keys or indexes:

JsonHelper json = new JsonHelper(jsonContent);

json.get("cats").get(0).get("name").stringValue(); // null
json.get("dogs").get(99999).get("name").stringValue(); // null
json.get("dogs").get(0).get(1).get("name").stringValue(); // null
json.get("dogs").get(0).get("name").boolValue(); // null
json.get("dogs").get(0).get("age").intValue(); // null

for (JsonHelper dog: json.get("cats")) {
  // not executed
}

for (Map.Entry<String, JsonHelper> element: json.get("dogs").entrySet()) {
  // not executed
}

License

See the LICENSE file for license rights and limitations.