Although above there is a huge solution pool, no one mentioned com.koushikdutta.ion: https://github.com/koush/ion
It's also asynchronous and very simple to use:
Ion.with(context).load("http://example.com/thing.json").asJsonObject().setCallback(new FutureCallback<JsonObject>() { @Override public void onCompleted(Exception e, JsonObject result) { // do stuff with the result or error }});