Если я понял суть вопроса, то можно сделать так:
interface OnResponseCallback {
void onResponse(int[] data);
}
class MainActivity implements OnResponseCallback {
public MainActivity() {
Response response = new Response(this);
}
@Override
public void onResponse(int[] data) {
//Обработка полученных данных
}
}
class Response {
OnResponseCallback mOnResponseComplete;
public Response(OnResponseCallback onResponseComplete) {
mOnResponseComplete = onResponseComplete;
returnDataToMainActivity();
}
void returnDataToMainActivity() {
mOnResponseComplete.onResponse(new int[] {1, 2, 3});
}
}