What does or should "public function create(): Node" return exactly?

Question

Seit gegrüsst
I playing around with javafx for a project, evaluating this technology.
When I'm displaying things on the screen through "CustomNodes" I have to override the "public function create(): Node" method.
In examples found on google, there's often created a new Group or something like that and than be returned.
Why can't I just return "this"?
What does or should "public function create(): Node" return exactly? And why is this so?
thx for response
carpe noctem
livevil
Edited by: livevil on Oct 14, 2008 4:28 PM
Edited by: livevil on Oct 14, 2008 4:29 PM

Answer 1

"public function create(): Node" method should return a graphic
representation of the class.
For example, FunctionGraph class below draws a mathematical functiuon:
import javafx.scene.*;
import javafx.scene.paint.*;
import javafx.scene.geometry.*;
import javafx.scene.transform.*;
import javafx.ext.swing.*;
import java.lang.Math;
import java.lang.System;
public class FunctionGraph extends CustomNode{
    attribute scale:Number = 1;
    attribute xMin: Number;
    attribute xMax: Number;
    attribute dx: Number = 1;
    attribute color: Color;
    attribute func: function(a: Number):Number;
    public function create():Node{
      var n = (xMax - xMin) / dx;
      var polyline = Polyline{ stroke: color };
      for(i in [0..n]){
        var x = xMin + i * dx;
        var y =  (this.func)(x);
        insert(   x * scale ) into polyline.points;
        insert( - y * scale ) into polyline.points;  
      return Group{ content: [ polyline] };
var w = 300;
var h = 300;
var xMin = -7;
var xMax = 7;
var dx = 0.05;
var scale = 20;
SwingFrame{
    width:  300
    height: 300
    title: "Function Graph"
    content: Canvas{
      content:  Group{
            transform: Translate.translate(w/2, h/2)
            content: FunctionGraph {
                xMin: xMin
                xMax: xMax
                scale: scale
                dx: dx
                color: Color.BLUE
                func: function(x:Number):Number{ return Math.sin(x); }               
    visible: true
}