How to convert a Java Object to a JSONObject?

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);

    }
}

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.

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);