i need to convert a POJO to a JSONObject (org.json.JSONObject)
I know how to convert it to a file:
ObjectMapper mapper = new ObjectMapper();
try {
mapper.writeValue(new File(file.toString()), registrationData);
} catch (JsonGenerationException e) {
e.printStackTrace();
} catch (JsonMappingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
But I dont want a file this time.
5 Answers
If we are parsing all model classes of server in GSON format then this is a best way to convert java object to JSONObject.In below code SampleObject is a java object which gets converted to the JSONObject.
SampleObject mSampleObject = new SampleObject();
String jsonInString = new Gson().toJson(mSampleObject);
JSONObject mJSONObject = new JSONObject(jsonInString);
If it's not a too complex object, you can do it yourself, without any libraries. Here is an example how:
public class DemoObject {
private int mSomeInt;
private String mSomeString;
public DemoObject(int i, String s) {
mSomeInt = i;
mSomeString = s;
}
//... other stuff
public JSONObject toJSON() {
JSONObject jo = new JSONObject();
jo.put("integer", mSomeInt);
jo.put("string", mSomeString);
return jo;
}
}
In code:
DemoObject demo = new DemoObject(10, "string");
JSONObject jo = demo.toJSON();
Of course you can also use Google Gson for more complex stuff and a less cumbersome implementation if you don't mind the extra dependency.
The example below was pretty much lifted from mkyongs tutorial. Instead of saving to a file you can just use the String json as a json representation of your POJO.
import java.io.FileWriter;
import java.io.IOException;
import com.google.gson.Gson;
public class GsonExample {
public static void main(String[] args) {
YourObject obj = new YourOBject();
Gson gson = new Gson();
String json = gson.toJson(obj); //convert
System.out.println(json);
}
}
Here is an easy way to convert Java object to JSON Object (not Json String)
import com.fasterxml.jackson.databind.ObjectMapper;
import org.json.simple.parser.JSONParser;
JSONObject jsonObject = (JSONObject) JSONValue.parse(new ObjectMapper().writeValueAsString(JavaObject));
How to get JsonElement from Object:
import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.gson.*;
final ObjectMapper objectMapper = new ObjectMapper();
final Gson gson = new Gson();
String json = objectMapper.writeValueAsString(source);
JsonElement result = gson.fromJson(json, JsonElement.class);
