get value of positions [x] [y] in array of buttons added to gridpane

Question

I have a doubt in the calculation of positions in a two-dimensional array of buttons added in a gridpane

class Position [lin,col]

public class Position {

    private int lin;
    private char col;

    public Position(int lin, char col) {
        this.col = col;
        this.lin = lin;
    }

    @Override
    public String toString() {
        return col + "" + lin;
    }
}

class GridPaneArrayButton

public class GridPaneArrayButton extends Application {

    @Override
    public void start(Stage primaryStage) {

        Image[][] img1 = new Image[9][9];
        Image[][] img2 = new Image[9][9];

        GridPane root = new GridPane();
        root.setPadding(new Insets(5));
        root.setAlignment(Pos.CENTER);

        Label label = new Label("CHESS TABLE 8X8");
        label.setFont(Font.font("Cambria", FontWeight.BOLD, 18));
        GridPane.setColumnSpan(label, 10);
        GridPane.setRowSpan(label, 2);
        root.add(label, 0, 0);
        GridPane.setHalignment(label, HPos.CENTER);

        TextArea text = new TextArea();
        GridPane.setColumnSpan(text, 10);
        GridPane.setRowSpan(text, 2);
        root.setVgap(1);
        root.add(text, 0, 25);
        GridPane.setHalignment(text, HPos.CENTER);
        text.getStyleClass().add("text-area");

        Button[][] btn = new Button[8][8];

        boolean changeColor = false;

        for (int i = 0; i < btn.length; i++) {

            for (int j = 0; j < btn.length; j++) {


                btn[i][j] = new Button("", new ImageView(img1[i][j]));

                btn[1][j] = new Button("", new ImageView(img1[0][8]));

                btn[6][j] = new Button("", new ImageView(img2[7][8]));

                btn[7][j] = new Button("", new ImageView(img2[i][j]));

                if (changeColor == false) {
                    btn[i][j].getStyleClass().add("btn_color_lightgrey");
                } else {
                    btn[i][j].getStyleClass().add("btn_color_grey");
                }
                btn[i][j].setPrefSize(65, 65);
                root.add(btn[i][j], j, i + 2);
                btn[i][j].setOnMouseClicked((MouseEvent e) -> {

                    StringBuilder str = new StringBuilder();

                    str.append("Position Gridpane X: ").append(e.getX()).append("\n");
                    str.append("Position Gridpane Y: ").append(e.getY()).append("\n");

                    int x = (int) e.getX();
                    int y = (int) e.getY();

                    int rx = ((int) e.getX() % 8);
                    int ry = ((int) e.getY() % 8);

                    int lin = (x - rx) / 8;
                    int col = (y - ry) / 8;

                    str.append("Line X: ").append(lin).append("\n");
                    str.append("Col Y: ").append(convCol(col)).append("\n");
                    str.append("Position XY : ").append(new Position(lin, convCol(col))).append("\n");
                    str.append("\n-----------------------------------------------------------------------------\n\n");

                    text.appendText(str.toString());
                });
                changeColor = !changeColor;
            }
            changeColor = !changeColor;
        }

        Scene scene = new Scene(root, 900, 900);
       scene.getStylesheets().add(this.getClass().getResource("styles.css").toExternalForm());

        primaryStage.setTitle("Grid Pane Example");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

    public static char convCol(int col) {
        switch (col) {
            case 1:
                return 'A';
            case 2:
                return 'B';
            case 3:
                return 'C';
            case 4:
                return 'D';
            case 5:
                return 'E';
            case 6:
                return 'F';
            case 7:
                return 'G';
            case 8:
                return 'H';
            default:
                return ' ';
        }
    }

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

After running, I got this result and it is incorrect

and the goal is to follow this logic

Any suggestions? I would appreciate.

Answer 1

Consider storing the position of the button in the button itself, using Node.setUserData() , and eliminate determining it depending on mouse click coordinates:

// store the position
btn[i][j].setUserData( new Position( btn.length - i, convCol( j + 1 ) ) );

// get it on mouse click
btn[i][j].setOnMouseClicked( ( MouseEvent e ) -> {
    StringBuilder str = new StringBuilder();
    str.append( "Position XY : " ).append( (( Node ) e.getSource()).getUserData() ).append( "\n" );
    text.appendText( str.toString() );
} );