Toggle icons in runtime:
In addition to the responses here, I found that once you have assigned an Icon to your application by the first time you cannot toggle it by just adding a new icon to your stage (this would be helpful if you need to toggle the icon of your app from on/off enabled/disabled).
To set a new icon during run time use the getIcons().remove(0) before trying to add a new icon, where 0 is the index of the icon you want to override like is shown here:
//Setting icon by first time (You can do this on your start method).
stage.getIcons().add(new Image(getClass().getResourceAsStream("enabled.png")));
//Overriding app icon with a new status (This can be in another method)
stage.getIcons().remove(0);
stage.getIcons().add(new Image(getClass().getResourceAsStream("disabled.png")));
To access the stage from other methods or classes you can create a new static field for stage in you main class so can access it from out of the start() method by encapsulating in on a static method that you can access from anywhere in your app.
public class MainApp extends Application {
private static Stage stage;
public static Stage getStage() { return stage; }
@Override public void start(Stage primaryStage) {
stage = primaryStage
stage.getIcons().add(new Image(getClass().getResourceAsStream("enabled.png")));
}
}
public class AnotherClass {
public void setStageTitle(String newTitle) {
MainApp.getStage().setTitle(newTitle);
MainApp.getStage().getIcons().remove(0);
MainApp.getStage().getIcons().add(new Image(getClass().getResourceAsStream("disabled.png")));
}
}