java - track change of nodes bound in javafx -

i want same thing asked in post track changes of nodes bound in javafx

i have : (edited) sscce:

public class floatcircle {  node node;   circle rectangle; bounds localtoscreen; static arraylist<objectbinding> list = new arraylist<>(); private objectbinding<bounds> boundsinscene ; pane root ;  public floatcircle(node node,pane root) {     this.node = node;    this.root =root;     this.rectangle = new circle();     this.rectangle.setmanaged(false);      initsetting();  }    public circle getfloatcircle() {     return rectangle; }  public void initsetting() {     boundsinscene = bindings.createobjectbinding(             () -> node.localtoscene(node.getboundsinlocal()),             node.localtoscenetransformproperty(),             node.boundsinlocalproperty());     boundsinscene.addlistener(new changelistener<bounds>() {          @override         public void changed(observablevalue<? extends bounds> observable, bounds oldvalue, bounds newvalue) {              setlocation(newvalue);             system.err.println("changed!!!!!!");         }      });     localtoscreen = node.localtoscene(node.getboundsinlocal());     setlocation(localtoscreen);     addcircle(); }  public void setlocation(bounds localtoscreen) {     int r = 10;             rectangle.setcenterx(localtoscreen.getminx() - r);             rectangle.setcentery(localtoscreen.getminy() - 5);             rectangle.setradius(r);      //    return rect;  }  public void addcircle(){             root.getchildren().add(rectangle);  }  }     public class selfcontained extends application {  arraylist<node> nodes = new arraylist<>();  @override public void start(stage primarystage) {     button btn = new button();      stackpane root = new stackpane();     root.getchildren().add(btn);     nodes.add(btn);      scene scene = new scene(root, 300, 250);      primarystage.settitle("hello world!");     primarystage.setscene(scene);     primarystage.show();      (int = 0; < nodes.size(); i++) {         node n = nodes.get(i);         floatcircle floatcircle = new floatcircle(n, root);      } }  /**  * @param args command line arguments  */ public static void main(string[] args) {     launch(args); }  } 

but problem changed method doesn't called correctly...it called 1 time....if add code in changed method instead of old 1 called correctly...but very slow

           floatcircle fc = new floatcircle(node);            fc.rectangle = rectangle ;            fc.setlocation(newvalue, directionid, alignment); 

can me? thank's...

since button , circle in example in same parent pane, more (and efficiently) binding circle's location button's boundsinparentproperty(). assume doing way because have real application in 2 nodes in different parents.

it looks localtoscenetransformproperty() getting garbage collected prematurely (see this). can fix using listener instead of binding:

public static class floatcircle {      node node;      circle rectangle;     pane root;      public floatcircle(node node, pane root) {         this.node = node;         this.root = root;         this.rectangle = new circle();         this.rectangle.setmanaged(false);          initsetting();      }      public circle getfloatcircle() {         return rectangle;     }      public void initsetting() {          changelistener<object> updater = (obs, oldvalue, newvalue) ->              setlocation(node.localtoscene(node.getboundsinlocal()));         node.boundsinlocalproperty().addlistener(updater);         node.localtoscenetransformproperty().addlistener(updater);          setlocation(node.localtoscene(node.getboundsinlocal()));         addcircle();     }      public void setlocation(bounds localtoscreen) {         int r = 10;         rectangle.setcenterx(localtoscreen.getminx() - r);         rectangle.setcentery(localtoscreen.getminy() - 5);         rectangle.setradius(r);     }      public void addcircle() {         root.getchildren().add(rectangle);      }  }