swing - Progress bars in Java -

i have code 2 methods.

public void fondo() { ... }        //gathers jframe background , system time public void recuperardatosinternet() {...} //connects url , gets data. 

when jframe running, @ beginning takes 4 or 5 seconds perform operations of methods.

while it's loading, frame displays totally empty 3 or 4 seconds until methods complete, frame shows , it's right.

how can make progress bar shows user it's loading? don't mean progressbar predetermined take "4000 ms". referring progressbar can take whatever takes, , bar doesn't reach 100% until methods complete.

if run heavy task in the event dispatch thread it's gonna freeze until finish avoid can execute download in thread using swingworker. follow link see complete example progressbar , special attention setprogress() publish() , process().

example:

public class myworker extends swingworker<integer, string> {    @override   protected integer doinbackground() throws exception {     // start     publish("start download");     setprogress(1);      // more work done     publish("more work done");     setprogress(10);      // complete     publish("complete");     setprogress(100);     return 1;   }    @override   protected void process(list< string> chunks) {     // messages received doinbackground() (when invoking publish() method)   } } 

and in client code:

    swingworker worker = new myworker();     worker.addpropertychangelistener(new myprogresslistener());     worker.execute();     class myprogresslistener implements propertychangelistener {       @override       public void propertychange(final propertychangeevent event) {         if(event.getpropertyname().equalsignorecase("progress")) {           downloadprogressbar.setindeterminate(false);           downloadprogressbar.setvalue((integer) event.getnewvalue());         }                }      }