Java SE (Java Platform, Standard Edition)

I am busying writing a simple application using JavaFX2. The goal is just to plot 2 nodes (the nodes are movable by dragging them) and then have a function to draw lines between these nodes. I finished the functions to add and move nodes (at the moment I am just using Ellipse shapes but I am going to replace it later with my own node class) but now I am struggling with the connecting lines. The actions to add a node or a line is from a dropdown menu and I have the following code on the line function:

 private void drawLine(MenuItem line) {

    final BooleanProperty lineActive = new SimpleBooleanProperty(false);
    final BooleanProperty clickOne = new SimpleBooleanProperty(false);
    final BooleanProperty clickTwo = new SimpleBooleanProperty(false);

    line.setOnAction(new EventHandler<ActionEvent>() {
        public void handle(ActionEvent t) {              
            lineActive.set(true);
        }
    });

    nodeGroup.setOnMousePressed(new EventHandler<MouseEvent>() {
        public void handle(final MouseEvent t1) {
            clickOne.set(true);

            if (lineActive.get()) {

                if (clickOne.get()) {
                    //get x and y of first node
                    x1 = ((Ellipse) t1.getTarget()).getCenterX();
                    y1 = ((Ellipse) t1.getTarget()).getCenterY();
                    clickOne.set(false);
                    clickTwo.set(true);
                }

                if (clickTwo.get()) {
                    nodeGroup.setOnMouseClicked(new EventHandler<MouseEvent>() {
                        public void handle(MouseEvent t2) {
                            //get x and y of second node
                            x2 = ((Ellipse) t2.getTarget()).getCenterX();
                            y2 = ((Ellipse) t2.getTarget()).getCenterY();

                            //draw line between nodes
                            final Line line = new Line();
                            line.setStartX(x1);
                            line.setStartY(y1);
                            line.setEndX(x2);
                            line.setEndY(y2);

                            canvas.getChildren().add(line);

                            clickTwo.set(false);
                            lineActive.set(false);                     
                        }
                    });
                }
            }
        }
    });
}

I just have the booleans to check for the first and second click to get the center of each node. My first question is when I click on the line function and add a line between 2 nodes, it doesn't seem to end the function, and any other nodes I click on gets a line to it. How can I prevent it from executing more than once.

And my second question is how can I "connect" the line to the nodes that if the node moves, the line stays in the center of the node?

Thanks.