swing - Setting up a progress bar in Java -

i have program , have tried implement progress bar code. bellow example of code currently. main gui in own class , instantiates other classes execute code within classes' methods. example follows:

class mainclass {     public javax.swing.jprogressbar progressbar;     private void combineactionperformed(java.awt.event.actionevent evt) {         combine combiner = new combine();         combiner.merge(folder);     } } 

it takes folder listing , goes combine class has following code:

public class combine extends swingworker<integer,integer>{     public void merge(folder []){ (for int i=0;i<folder.length;i++){         merge(folder[i]);      }     public void merge(folder[]){         output stream;     } } 

how implement swing worker in example make progress update mainclass progress bar each iteration of occurs?

to begin, worker missing methods should implement, such doinbackground() , done(). need constructor pass folder[].

public class combine extends swingworker<integer,integer>{      folder[] folders;        public combine (folder[] folders)     {   this.folders = folders; }             private void merge(folder [])     { (for int i=0;i<folder.length;i++)         {             merge(folder[i]);             //send message of progress here, executed             //from doinbackground()             setprogress(....);         }      }     private void merge(folder){         output stream;     }      protected integer doinbackground()     {         merge(folders);         return null;     }      protected void done()     { .... } } 

then call worker with

combine combiner = new combine(folders); combiner.execute(); 

to track progress, example swingworker api:

 combiner.addpropertychangelistener(      new propertychangelistener() {          public  void propertychange(propertychangeevent evt) {              if ("progress".equals(evt.getpropertyname())) {                  progressbar.setvalue((integer)evt.getnewvalue());              }          }      });