Button color change in javafx

Question

This is my code for drawing bus seat. Each Button represents a seat drawn in the GridPane . I want to change the seat color from green to yellow when someone clicks on the seat. So far I have done this. If I click on the button it prints "hellow world" in output window. But button color doesn't change in the UI. Here is my code:

public static GridPane drawBus(int rows, int col, String ss){
    GridPane table = new GridPane();
    table.setHgap(5);
    table.setVgap(5);
    table.setAlignment(Pos.CENTER);
    String seatName;

    if(ss.equals("ROW WISE")||ss.equals("Row Wise")||ss.equals("row wise")){
    for(int i=0; i<rows; i++){

        for(int j=0;j<col; j++)
        {
        seat=new Button();
        seat.setAlignment(Pos.CENTER);
        seat.setPrefSize(80, 31);

        seatName=numToString(i+1)+(j+1);
        seat.setText(seatName);
        seat.setStyle("-fx-background-color: MediumSeaGreen");


        seat.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent event) {

            seat.setStyle("-fx-background-color: Yellow");
            System.out.println("Hello World!");

        }
        });

        busSeatList.put(seatName, 0);

        //add them to the GridPane
        table.add(seat, j, i); //  (child, columnIndex, rowIndex)

     }


    }
    }
    else
    {
      for(int i=0; i<rows; i++){

        for(int j=0;j<col; j++)
        {
        seat=new Button();
        seat.setAlignment(Pos.CENTER);
        seat.setPrefSize(80, 31);

        seatName=(i+1)+numToString(j+1);
        seat.setText(seatName);
        seat.setStyle("-fx-background-color: MediumSeaGreen");


        seat.setOnAction(new EventHandler<ActionEvent>() {
        @Override
        public void handle(ActionEvent event) {
            System.out.println("Hello World!");
            //seat.setStyle("-fx-background-color: Yellow");

        }
        });



        busSeatList.put(seatName, 0);
        //add them to the GridPane
        table.add(seat, j, i); //  (child, columnIndex, rowIndex)


       }


    }


    }


    return table;
}

Answer 1

It's easier to use a class that already implements this functionality and use a stylesheet. ToggleButton is a class that suits your needs:

ToggleButton btn = new ToggleButton("Say 'Hello World'");
btn.setOnAction((ActionEvent event) -> {
    System.out.println("Hello World!");
});

...
scene.getStylesheets().add(getClass().getResource("style.css").toExternalForm());

style.css

.toggle-button {
    -fx-background-color: green;
}

.toggle-button:selected {
    -fx-background-color: yellow;
}

---

BTW: the issue in your code is probably using a field ( seat ) to store the button. This way if you press any button, the last one created will always be the one modified. Use a final local variable declared in the inner loop instead if you want to keep using your implementation.

Answer 2

My advice for dynamic style is to use custom PseudoClass and css:

Pseudo class in code:

public static final PseudoClass PSEUDO_CLASS_FOO = PseudoClass.getPseudoClass("foo");

// ... then in your creation method
// Note using java8 lambda is more concise:
seat.setOnAction(event->{
        System.out.println("Hello World!");
       seat.pseudoClassStateChanged(PSEUDO_CLASS_FOO, true);

    });

In your css:

Button:foo {
    -fx-background-color: yellow;
}