java - Bind property to ObjectProperty's property -

i trying make line points node in property:

objectproperty<node> pointedtonode = new simpleobjectproperty(); 

i want line point so:

line.endxproperty().bind(pointedtonode.get().layoutxproperty()); 

the problem when pointedtonode changes, binded value (pointedtonode.get()) has changed, , layoutxproperty() no longer valid.

i need line invisible if value of pointedtonode null.

i tried custom double bindings no success.

using plain api:

changelistener<number> xlistener = (obs, oldx, newx) ->      line.setendx(newx.doublevalue()); pointedtonode.addlistener((obs, oldnode, newnode) -> {     if (oldnode != null) {         oldnode.layoutxproperty().removelistener(xlistener);     }     if (newnode != null) {         newnode.layoutxproperty().addlistener(listener);     } }); 

or, using easybind framework:

line.endxproperty().bind(     easybind.select(pointedtonode)     .selectobject(node::layoutxproperty)     .orelse(-1)); // value if pointedtonode null 

you can try using bindings.select (standard) api, looks bit easybind has several disadvantages: doesn't deal elegantly null values in "chain" (i.e. if pointedtonode.get() null); not typesafe; , prone premature garbage collection.

line.endxproperty().bind(bindings.selectdouble(pointedtonode, "layoutx")); 

i recommend easybind approach, or, if don't want use third-party library reason, use "by hand" listener approach in first code block.

for visibility, do

line.visibleproperty().bind(pointedtonode.isnull());