How to remove special characters from JSON stream, so that I can use gson API to convert JSON objects to JAVA objects?

Question

I am trying to use Google gson API to serialize JSON objects to java objects. I need to remove special characters from this stream for the serialization. How do I achieve t

Answer 1

It works perfectly as expected. There is no need to remove these special characters from JSON stream to convert it into Java object.

Please have a look at below sample code:

BufferedReader reader = new BufferedReader(new FileReader(new File("json.txt")));
MyJSONObject data = new Gson().fromJson(reader, MyJSONObject.class);
System.out.println(new GsonBuilder().setPrettyPrinting().create().toJson(data));

class MyJSONObject {
    private String color;
    private String imageUrl;
    private String styleId;
    private String originalPrice;
    private String price;
    private String productUrl;
    private String percentOff;
    // getter & setter
}

output: (I have deleted URLs from the output due to constrain of StackOverflow site)

{
  "color": "Arctic White",
  "styleId": "1788212",
  "originalPrice": "$64.95",
  "price": "$64.95",
  "percentOff": "0%"
}

---

You can try with JsonDeserializer to deserializer it as per your need.

I have already posted a sample code on it. Find it HERE

---

EDIT

Here is the sample code using JsonDeserializer.

Sample code :

BufferedReader reader = new BufferedReader(new FileReader(new File("resources/json29.txt")));

class MyJSONObject {
    private String color;
    private String imageUrl;
    private String styleId;
    private double originalPrice;
    private double price;
    private String productUrl;
    private double percentOff;
    // getter & setter
}

class MyJSONObjectDeserializer implements JsonDeserializer<MyJSONObject> {

    @Override
    public MyJSONObject deserialize(final JsonElement json, final Type typeOfT,
            final JsonDeserializationContext context) throws JsonParseException {

        JsonObject jsonObject = json.getAsJsonObject();

        MyJSONObject myJSONObject = new MyJSONObject();
        myJSONObject.setColor(jsonObject.get("color").getAsString());
        myJSONObject.setImageUrl(jsonObject.get("imageUrl").getAsString());
        myJSONObject.setStyleId(jsonObject.get("styleId").getAsString());
        myJSONObject.setProductUrl(jsonObject.get("productUrl").getAsString());

        try {
            String price = jsonObject.get("price").getAsString();
            String originalPrice = jsonObject.get("originalPrice").getAsString();
            String percentOff = jsonObject.get("percentOff").getAsString();

            myJSONObject.setPrice(Double.valueOf(price.substring(1)));
            myJSONObject.setOriginalPrice(Double.valueOf(originalPrice.substring(1)));
            myJSONObject.setPercentOff(Double.valueOf(percentOff.substring(0,
                    percentOff.length() - 1)));

        } catch (NumberFormatException e) {
            e.printStackTrace();
        }

        return myJSONObject;
    }
}

MyJSONObject data = new GsonBuilder()
        .registerTypeAdapter(MyJSONObject.class, new MyJSONObjectDeserializer()).create()
        .fromJson(reader, MyJSONObject.class);

System.out.println(new GsonBuilder().setPrettyPrinting().create().toJson(data));

Answer 2

The easiest way would be to turn the stream into a string, use a regex or something to replace the undesired characters, then invoke gson to convert the corrected string into the Java object you want.

Answer 3

As I understand it, your object's JSON representation contains a value such as "0%" (which is officially a String from JSON's point of view). This is certainly valid JSON, and GSON should accept it...if you were deserializing it to something that was designed to contain a String.

My guess is that you actually want the "0" to be deserialized into a numeric type. In this case, you can't rely on GSON to do what you want automatically, and you will need to write a custom deserializer.

The example in the link above shows how one might do this for a DateTime object:

private class DateTimeDeserializer implements JsonDeserializer<DateTime> {
  public DateTime deserialize(JsonElement json, Type typeOfT, JsonDeserializationContext context)
      throws JsonParseException {
    return new DateTime(json.getAsJsonPrimitive().getAsString());
  }
}

In your case, you will still need to do a getAsString(), but instead of passing it to the DateTime constructor, you would want to apply your own transformations (strip the "%", parse the numeric part, etc) and return the appropriate data type that corresponds to your object.