Radoslaw Zubek

I have problem with some way of encapsulating boilerplate code. To avoid writing some part of code for http requests and responses each time, I decided to encapsulate it in one method. This method gets only query string and listener for response.

void performRequest(String queryString, ResponseListener listener) {...} ... interface ResponseListener { void httpResponse(int status) throws BaseException; }

My problem is, that I have to throw a various exceptions depends on 'status' variable and this exceptions are thrown through 'BaseException'.

public void doSomeWork(String params) throw DerivedException1, DerivedException2 { try { performRequest(params, new ResponseListener() { public void httpRequest(int status) throws BaseException { switch (status) { case 0: /* ok */ break; case 1: throw new DerivedException1(); case 2: throw new DerivedException2(); default: throw new RuntimeException("status: " + status); } } }); } catch (BaseException e) { if (e instanceof DerivedException1) { throw (DerivedException1) e; } if (e instanceof DerivedException2) { throw (DerivedException2) e; } } }

My question is how to avoid this ugly code for casting exceptions and encapsulate some boilerplate code.