java - DRY: a case with AsyncTasks -

i'm developing android app has lot of different requests web services. every request done in subclass of asynctask in manner:

(new asynctask<string, void, object1>() {     @override     protected object1 doinbackground(string... params) {         // network request , parsing object1         object1 obj = new object1();         obj1 = parser.parseobject1(httpclient.execute(...));         return obj1;     }      @override     protected object1 onpostexecute(object1... ret) {         return ret[0];     } }).execute(); 

object1 placeholder different objects (car, bicycle, truck...), each 1 in different asynctask.

what alternatives other returning output of httpclient in string , parsing in main thread (ui thread)? avoid parsing in ui thread sounds reasonable if it's going parse lot of data, right?

-= update =-

let me rephrase question: i'm asking more intelligent way develop application avoiding being repetitive (asynctask has lot of boilerplate code). way did creating 20+ subclasses of asynctask, not dry (do not repeat yourself).

in ios have lambda expressions callbacks done in web requests easy , succinct.

you can create classes contain of boilerplate code. e.g.

public class specialasynctask<t> extends asynctask<string, void, t> {      public interface resultprovider<t> {         t generateresultinbackground(string... params);     }      public interface resultconsumer<t> {         void handleresultinforeground(t result);     }      private final resultprovider<t> mprovider;     private final resultconsumer<t> mconsumer;     private specialasynctask(resultprovider<t> provider, resultconsumer<t> consumer) {         mprovider = provider;         mconsumer = consumer;     }      @override     protected t doinbackground(string... params) {         return mprovider.generateresultinbackground(params);     }      @override     protected void onpostexecute(t result) {         mconsumer.handleresultinforeground(result);     }      public static <t> void execute(resultprovider<t> provider, resultconsumer<t> consumer, string... params) {         new specialasynctask<t>(provider, consumer).execute(params);     } } 

is example how keep object1 generic parameter while being able specify object needs implement interface handle code otherwise have inside new asynctask instance.

with schema example define common code static content:

class providers {     public static final resultprovider<string> http_getter = new resultprovider<string>() {          @override         public string generateresultinbackground(string... params) {             return magichttplibrary.getcontentasstring(params[0]);         }      }; } 

and can use providers.http_getter parameter instead of implementing doinbackground. or create new class hierarchy of implement 1 of interfaces different methods access them (like factories example)

use of above example example below

class user extends activity implements resultconsumer<string> {      @override     protected void oncreate(bundle savedinstancestate) {         specialasynctask.execute(providers.http_getter, , "http://google.com");         specialasynctask.execute(providers.http_getter, , "http://yahoo.com");     }      @override     public void handleresultinforeground(string result) {         toast.maketext(this, result, toast.length_long).show();     } } 

and there more or less no repeated code besides different method calls. depends on how want use class , changes in code know how design that. identify parts need parametrized , move code repeats re-used place (inheritance / composition).