如何检查鼠标光标是否在 Java FX 的按钮上？

Question

I'm new to Java and I'm wondering if it is possible to check if mouse cursor is for example on the button? I mean not getting clicking events but just moving cursor on the button.

I had working code getting click and then printing something, but I want to change it a little and I can't find out why it doesn't work.

public class Main extends Application implements EventHandler<MouseEvent> {

Button button;
Stage window;
Scene scene;

@Override
public void start(Stage primaryStage) throws Exception {
    Parent root = FXMLLoader.load(getClass().getResource("sample.fxml"));
    primaryStage.setTitle("Where's the button?");
    button.setText("Click me!");
    button.setOnMouseMoved(this);

    StackPane layout = new StackPane();
    layout.getChildren().add(button);

    Scene scene = new Scene(layout, 300,350);
    primaryStage.setScene(scene);
    primaryStage.show();

}


public static void main(String[] args) {
    launch(args);
}

@Override
public void handle(MouseEvent actionEvent) {
    System.out.println("You clicked the button!");
}
}

Answer 1

I have made small code for you. Take a look. It prints in the console "Ho-Ho-Ho-Hovereed!" once you hover over your button.

 @Override
    public void start(Stage primaryStage) {
        Button btn = new Button();
        btn.setText("Hover over me.'");

        btn.hoverProperty().addListener((event)->System.out.println("Ho-Ho-Ho-Hovereeed!"));        

        StackPane root = new StackPane();
        root.getChildren().add(btn);

        Scene scene = new Scene(root, 300, 250);

        primaryStage.setTitle("Mouse manpulation example in JavaFX!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

Answer 2

i guess you can do that with event handler or css, like...

button.setOnMouseEntered(new EventHandler<MouseEvent>() {
        @Override
        public void handle(MouseEvent mouseEvent) {                
            System.out.println("Cursor Over Button");
        }
    });

or/with styles (css)

.button:hover{ -fx-background-color: red; }

Answer 3

Each Node provides a hover property to track whether the mouse cursor is hovering over it or not. By using a simple listener, you can detect when the mouse starts and stops hovering:

button.hoverProperty().addListener((observable, oldValue, newValue) -> {
    if (newValue) {
        System.out.println("Hovering...");
    } else {
        System.out.println("Retreating...");
    }
});

With this listener, newValue will always be true if the mouse is currently hovering over the button and change to false when the mouse leaves the area.

Answer 4

There is also a useful check on a Node - isHover() You can use it on MouseEvents to check if the mouse is hovering over the needed node. Such a tip ;)

Answer 5

button.setOnMouseEntered( (event ) -> {
        button.setTranslateX(button.getTranslateX() + 20);
        button.setTranslateY(button.getTranslateY() + 20);

    });`

Replace button.setOnMouseMoved(this); with my code. This will do!