Can't rotate a shape in Javafx - javafx

Question

I'm having trouble rotating a shape in JavaFX. Here's some code in which I want the arrowhead to point in the same direction as the line (yes, I will be adding a translation later, to put it on the end of the line, but one thing at a time).
The println statement is showing me that theta is updating correctly as I move the start and end points around, but the arrowhead stays stubbornly at the original angle. Is there another step I have to do in order to get shape to rotate, or should I be doing it a different way?
package application.view;
public class Connector extends Group {
private final DoubleProperty startX;
private final DoubleProperty startY;
private final DoubleProperty endX;
private final DoubleProperty endY;
public Connector(Line line, Polygon arrowhead, Preferences prefs) {
arrowhead.setStroke(Color.BLACK);
arrowhead.setStrokeWidth(1);
arrowhead.setFill(Color.CORNFLOWERBLUE);
startX = new SimpleDoubleProperty();
startY = new SimpleDoubleProperty();
endX = new SimpleDoubleProperty();
endY = new SimpleDoubleProperty();
thetaBinding = new DoubleBinding() {
{
super.bind(startX, startY, endX, endY);
}
#Override
protected double computeValue() {
return Math.atan2(getEndY() - getStartY(), getEndX() - getStartX());
}
};
theta = new SimpleDoubleProperty();
theta.bind(thetaBinding);
theta.addListener(new ChangeListener<Number>() {
#Override
public void changed(ObservableValue<? extends Number> observable,
Number oldValue, Number newValue) {
System.out.println(newValue);
arrowhead.rotateProperty().set((Double)newValue);
}
});
lineLength = new DoubleBinding() {
{
super.bind(startX, startY, endX, endY);
}
#Override
protected double computeValue() {
return Math.hypot(getEndX() - getStartX(), getEndY() - getStartY()) - prefs.getDouble("CONNECTOR_ARROW_LENGTH", Defaults.CONNECTOR_ARROW_LENGTH);
}
};
lineEndX = new DoubleBinding() {
{
super.bind(startX, lineLength, theta);
}
#Override
protected double computeValue() {
return startX.get() + lineLength.get() * Math.cos(theta.get());
}
};
lineEndY = new DoubleBinding() {
{
super.bind(startY, lineLength, theta);
}
#Override
protected double computeValue() {
return startY.get() + lineLength.get() * Math.sin(theta.get());
}
};
arrowhead.getPoints().setAll(new Double[] {
0.0, 0.0,
0.0, prefs.getDouble("CONNECTOR_ARROW_HALF_WIDTH", Defaults.CONNECTOR_ARROW_HALF_WIDTH),
prefs.getDouble("CONNECTOR_ARROW_LENGTH", Defaults.CONNECTOR_ARROW_LENGTH), 0.0,
0.0, -prefs.getDouble("CONNECTOR_ARROW_HALF_WIDTH", Defaults.CONNECTOR_ARROW_HALF_WIDTH),
});
line.startXProperty().bind(startX);
line.startYProperty().bind(startY);
line.endXProperty().bind(lineEndX);
line.endYProperty().bind(lineEndY);
getChildren().addAll(line, arrowhead);
}
public final DoubleBinding thetaBinding;
public final DoubleProperty theta;
public final DoubleBinding lineLength;
public final DoubleBinding lineEndX;
public final DoubleBinding lineEndY;
public double getStartX() {
return startX.get();
}
public void setStartX(double value) {
startX.set(value);
}
public DoubleProperty startXProperty() {
return startX;
}
public double getStartY() {
return startY.get();
}
public void setStartY(double value) {
startY.set(value);
}
public DoubleProperty startYProperty() {
return startY;
}
public double getEndX() {
return endX.get();
}
public void setEndX(double value) {
endX.set(value);
}
public DoubleProperty endXProperty() {
return endX;
}
public double getEndY() {
return endY.get();
}
public void setEndY(double value) {
endY.set(value);
}
public DoubleProperty endYProperty() {
return endY;
}
}