MainActivity.java

gistfile1.txt

Call post(String url, Callback callback) throws IOException{
    RequestBody formBody = new FormBody.Builder()
            .add("To", mTo.getText().toString())
            .add("Body", mBody.getText().toString())
            .build();
    Request request = new Request.Builder()
            .url(url)
            .post(formBody)
            .build();
            
    Call response = mClient.newCall(request);
    response.enqueue(callback);
    return response;
}