java - Is this a convenient way of running code in a background thread and return a result via a callback executed in the calling thread? -

in last days have found myself using approach asynchronously performing long operation (several seconds), , return value via callback must execute on caller thread, typically but not necessarily ui thread.

public abstract class dosomethingcallback {     public abstract void done(object result); }  public void dosomething(final object param, final dosomethingcallback dosomethingcallback) {     // instantiate handler calling thread     final handler handler = new handler();      // start running long operation in thread     new thread(new runnable() {         @override         public void run() {             // long operation using "param" input...             object result = longoperation(param);              // return result via callback, run in caller thread             handler.post(new runnable() {                 @override                 public void run() {                     dosomethingcallback.done(clearbytes);                 }             });         }     }).start(); } 

this seems work pretty , simple use. however, somehow suspect might have problems i'm not aware of. question is, what potential issues of approach? better alternatives manually creating , running thread? i'm seeking simplicity , robustness.

the problem such approach breaks encapsulation: second thread not computes result, dictates caller thread should it. i'd better refactor code follows:

public abstract class dosomethingcallback {     final handler handler = new handler();      public void post(final object result) {         handler.post(new runnable() {             @override             public void run() {                 dosomethingcallback.done(result);             }         });     }      public abstract void done(object result); }  public void dosomething(final object param, final dosomethingcallback dosomethingcallback) {     // instantiate handler calling thread    final dosomethingcallback handler = new dosomethingcallback () {       void done(object result) {         ...       }    };     // start running long operation in thread    new thread(new runnable() {        @override        public void run() {            // long operation using "param" input...            object result = longoperation(param);             // return result via callback, run in caller thread            handler.post(result);         });       }     }).start();  }