java - Does this design make sense? -

does below design you? design pattern? how improve if think needs refactoring?

  public class fruitfetcher {     public static void main(string[] args) {         fruitfetcher fetcher = new fruitfetcher();         apple apple = (apple) fetcher.fetch(new fetchapplerequest());     }       public fruit fetch(fetchfruitrequest request){         fruit fruit = null;          if(request.getfruitname().equals(fetchapplerequest.request_name)){             fruit = new apple();         }else if (request.getfruitname().equals(fetchbananarequest.request_name)){             fruit =  new banana();         }         return fruit;     }  }  abstract class fetchfruitrequest{      abstract public string getfruitname();   }  class fetchapplerequest extends fetchfruitrequest{     static string request_name = "fetch_apple";      @override     public string getfruitname() {         return request_name;     } }  class fetchbananarequest extends fetchfruitrequest{     static string request_name = "fetch_banana";      @override     public string getfruitname() {         return request_name;     } }  class fruit { }  class apple extends fruit{  }  class banana extends fruit{  }  

in code, clients of fruitfetcher need upcast fruit right type, think correct?

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edit: answer elite gentleman's question, modified code show reqeust needs type other simple string.

does getresponse() in paymentserver still kind of 'ugly'? how re-fector it?

   public class paymentserver {       public static void main(string[] args) {         paymentserver server = new paymentserver();         //set pin         setpinresponse setpinresponse = (setpinresponse) server.getresponse(new setpinrequest("apin"));         system.out.println(setpinresponse.issuccess());          //make payment         makepaymentresposne makepaymentresponse = (makepaymentresposne) server.getresponse(new makepaymentrequest(new money("5.00)"),"apin"));         system.out.println(makepaymentresponse.issuccess());     }         public response getresponse(request request){         response aresponse = null;          if(request.getrequestname().equals(setpinrequest.request_name)){             aresponse = new setpinresponse();         }else if (request.getrequestname().equals(makepaymentrequest.request_name)){             aresponse =  new makepaymentresposne();         }         return aresponse;     }  }  abstract class request{     abstract public string getrequestname();  }  class setpinrequest extends request{     static string request_name = "set_pin";     private string pin;      setpinrequest(string pin){     this.pin = pin;     }      @override     public string getrequestname() {         return request_name;     }      boolean setpin(){     //code set pin     return true;     } }  class makepaymentrequest extends request{     static string request_name = "make_payment";     private money amount;     private string pin;      makepayment(money amount, string pin){     this.amount = amount;     this.pin = pin;     }      @override     public string getrequestname() {         return request_name;     } }   abstract class response {     abstract protected boolean issuccess();  }  class setpinresponse extends response{      @override     protected boolean issuccess() {     return true;     }  }  class makepaymentresposne extends response{     @override     protected boolean issuccess() {     return false;     }  }  

thanks,

sarah

your design pretty close factory pattern. "fetcher" fruit factory, ask fruit of special type , fruit.

the "request" part looks bit complicated. consider using enums:

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public enum fruittype{   apple, banana } 

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public fruitfetcher {     public static fruit fetch(fruittype type) {      switch(type) {        case apple:  return new apple();        case banana: return new banana();      }    }    return null; } 

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edit - it's still pretty complicated. takes while understand, want achieve , indicator there must easier design.

first - if request , response classes offer nothing abstract method declarations, should refactor code code both types interfaces. 1 step towards improved readability.

second - getresponse methd can simplified. don't need (ugly) getname construct - check type of request object:

public response getresponse(request request){     response aresponse = null;      if(request instanceof setpinresponse) {         aresponse = new setpinresponse((setpinrequest) request);     } else if (request instanceof makepaymentresposne) {         aresponse =  new makepaymentresposne((makepaymentrequest) request);     }      return aresponse; }