public void initialize() {


        TranslateTransition left_up, left_down, right_up, right_down;

        left_up = new TranslateTransition(new Duration(1000), leftPlayer);
        left_up.setByY(-500);
        left_down = new TranslateTransition(new Duration(1000), leftPlayer);
        left_down.setByY(500);
        right_up = new TranslateTransition(new Duration(1000), rightPlayer);
        right_up.setByY(-500);
        right_down = new TranslateTransition(new Duration(1000), rightPlayer);
        right_down.setByY(500);

        ball.setFocusTraversable(true);
        ball.requestFocus();
        ball.setOnKeyPressed(event -> {
            if (event.getCode().compareTo(KeyCode.W) == 0) {
                left_up.play();
                //leftPlayer.setLayoutY(0);
            } else if (event.getCode().compareTo(KeyCode.S) == 0) {
                left_down.play();
                //leftPlayer.setLayoutY(500-120);
            } else if (event.getCode().compareTo(KeyCode.UP) == 0) {
                //rightPlayer.setLayoutY(0);
            } else if (event.getCode().compareTo(KeyCode.DOWN) == 0) {
                //rightPlayer.setLayoutY(500-120);
            }
        });
        ball.setOnKeyReleased(event -> {
            if (event.getCode().compareTo(KeyCode.W) == 0) {
                left_up.stop();
            } else if (event.getCode().compareTo(KeyCode.S) == 0) {
                left_down.stop();
            }
        });
    }