java - JavaFX Listview bind button to the index of the cell -

im trying build custom view javafx allows 2 buttons "edit user" , "view user" placed in cell.

i have adapter built having trouble assigning index button when cell created, problem when click button within cell null pointer excpetion.

edit 07/04/2014 : have updated program logic little still struggling find solution problem - index assigned correct, incorrect ( set log give me current index , fluctuates drastically, leads me conclude cell constructor unreliable)

i use following code : populatelistview():

public void populatelistview() {      // 0 index each time list view repopulated      // bind correct button     index = 0;      // refresh lists contents null     lstnotes.setitems(null);      // observable list containing items add     observablelist notes = populateobservable(thistenant.getnotes());      // set items returned populateobservable(t);     lstnotes.setitems(notes);     lstnotes.setfixedcellsize(50);      // use cell factory custom styling     lstnotes.setcellfactory(new callback<listview, listcell>() {         @override         public listcell call(listview listview) {             notecell ncell = new notecell(index, controller);             index++;             ncell.getstyleclass().add("border-bottom");             return ncell;         }     }); } 

the comments self explanatory here - observable list of items populated via method - populateobservable(notelist n):

public observablelist populateobservable(arraylist<note> notesarray) {      observablelist notes = fxcollections.observablearraylist();      // loop through users notes array , create listview item     for(int = 0; < notesarray.size(); i++) {         note thisnote = notesarray.get(i);         notes.add(thisnote.getmessage());     }      return notes; } 

finally custom view constructed in cell factory (the styling irrelevant question), should noted reference controller passed can access methods - within notecell class have method delete row @ given index (this produces skewed results)

 cross.setonmouseclicked(new eventhandler<mouseevent>() {       @override       public void handle(mouseevent mouseevent) {           screensframework.loggeneral.writetofile("i removing index " + string.valueof(thisindex));           if(thistenant.removenoteat(thisindex, true)){               controller.populatelistview();           } else {               controller.populatelistview();           }       }   }); 

the call populatelistview() there refresh contents of listview , rebuild dependent on tenant's updated note array.

the removenoteat() method sends delete query db , removes note tenants note array @ given index (but not correct index stated above, can't find effective way bind button listviews cell , feeble attempt @ passing index not seem work).

i hope update provides clearer scope question, please request if need more information clearer understanding of this.

edit: notecell code:

public class notecell extends listcell<string> { hbox hbox = new hbox(); hbox c = new hbox(); pane b = new hbox(); pane pane = new pane(); label msg = new label(); label date = new label(); button cross = new button(); tenant thistenant; int thisindex;  string lastitem;   public notecell(int index, userinfocontroller controller) {     super();      try{         thistenant = controller.gettenant();         note currnote = thistenant.getnoteat(index);         date = new label(currnote.getdate());         system.out.println(thistenant.getnotes());         thisindex = index;          date.setstyle("-fx-text-fill: #fff !important; -fx-font-family: helvetica; -fx-font-weight: bold; -fx-font-size: 12px; -fx-background-color: #f9246b; -fx-border-color: #fe246c; -fx-padding: 8 8 6 8; -fx-border-radius: 6; -fx-background-radius: 6");         b.setstyle("-fx-padding: 10px 5px 10px 5px");         msg.setstyle("-fx-text-fill: #fafafa; -fx-font-size: 14px; -fx-font-family: 'open sans light'; -fx-label-padding: 10px");         cross.getstyleclass().add("button_close");         cross.settranslatey(20);         msg.setalignment(pos.center_left);          pane.settranslatey(20);         b.getchildren().add(date);         c.getchildren().add(cross);         hbox.getchildren().addall(b, msg, pane, cross);         hbox.sethgrow(pane, priority.always);           // deletes note         cross.setonmouseclicked(new eventhandler<mouseevent>() {             @override             public void handle(mouseevent mouseevent) {                 screensframework.loggeneral.writetofile("i removing index " + string.valueof(thisindex));                 if(thistenant.removenoteat(thisindex, true)){                     controller.populatelistview();                 } else {                     controller.populatelistview();                 }             }         });      } catch (exception e) {         screensframework.logerror.writetofile(e.getmessage());     } }    @override protected void updateitem(string item, boolean empty) {      super.updateitem(item, empty);     settext(null);  // no text in label of super class     if (empty) {         lastitem = null;         setgraphic(null);     } else {         lastitem = item;         msg.settext(item!=null ? item : "<null>");         setgraphic(hbox);     } } 

}

edit: there way when creating listview cells pass current index of cell "cellfactory"?

regards, alex

every cell knows index:

public class demo extends application {      listview<string> list = new listview<string>();      observablelist<string> data = fxcollections.observablearraylist(             "chocolate", "salmon", "gold", "coral", "darkorchid",             "darkgoldenrod", "lightsalmon", "black", "rosybrown", "blue",             "blueviolet", "brown");      @override     public void start(stage stage) {         vbox box = new vbox();         scene scene = new scene(box, 200, 200);         stage.setscene(scene);         box.getchildren().addall(list);         vbox.setvgrow(list, priority.always);          list.setitems(data);          list.setcellfactory(new callback<listview<string>, listcell<string>>() {             @override             public listcell<string> call(listview<string> list) {                 return new buttoncell();             }         });         stage.show();     }      static class buttoncell extends listcell<string> {         @override         public void updateitem(string item, boolean empty) {             super.updateitem(item, empty);             if (item != null) {                 final button btn = new button(item + " index " + getindex());                 btn.setonaction(new eventhandler<actionevent>() {                     @override                     public void handle(actionevent event) {                         system.out.println("i " + getitem() + " index " + getindex());                     }                 });                 setgraphic(btn);             } else {                 setgraphic(null);             }         }     }      public static void main(string[] args) {         launch(args);     } }