在 JavaFX 中让棋子转到您想要的磁贴？

Question

我目前正在创建一个跳棋类型的游戏，虽然我可以让方块在您每次点击它们时向上、向下移动等，但当涉及到点击棋子然后点击方块时，我处于不知道如何让它发挥作用。

这是棋子和棋盘的事件处理程序

class CircleEventHandler implements EventHandler<MouseEvent>{
    int Crow;
    int Ccol;
    @Override
    public void handle(MouseEvent event) {
        System.out.println("Mouse Clicked");

        Circle c = (Circle)event.getSource();
        Crow = gp.getRowIndex(c);
        Ccol = gp.getColumnIndex(c);
        System.out.println("row is " + Crow + " & col is " + Ccol);

        gp.getChildren().remove(c);


    }

}

class RectangleEventHandler implements EventHandler<MouseEvent>{

    @Override
    public void handle(MouseEvent event) {

        Rectangle r = (Rectangle)event.getSource();
        int row = gp.getRowIndex(r);
        int col = gp.getColumnIndex(r);
        System.out.println("row is " + row + " & col is " + col);

        gp.add(c, row, col);


    }

}

运行这段代码会给我一个空指针异常，并指向矩形事件处理程序中的 "gp.add(c, row, col);"。我不确定如何让它工作，有人可以指出我正确的方向吗？

Answer 1

你可以，例如使这些处理程序类成为内部类并将数据保存在封闭的实例中以使其工作。

以下示例仅演示如何根据之前单击的圆圈的颜色重新着色矩形，但它应该演示如何传递信息。

public class Board {

    public Board(GridPane grid) {
        this.grid = grid;
    }

    private final GridPane grid;
    private Circle selectedCircle;

    public class CircleEventHandler implements EventHandler<MouseEvent> {

        @Override
        public void handle(MouseEvent event) {
            // store info about circle clicked in enclosing instance
            selectedCircle = (Circle) event.getSource();
        }

    }

    public class RectangleEventHandler implements EventHandler<MouseEvent> {

        @Override
        public void handle(MouseEvent event) {

            if (selectedCircle != null) {
                // use field of enclosing instance to retrieve color of the circle
                Rectangle r = (Rectangle) event.getSource();
                r.setFill(selectedCircle.getFill());
                selectedCircle = null;
            }

        }

    }

}

@Override
public void start(Stage primaryStage) {
    GridPane root = new GridPane();
    root.addRow(0, new Circle(50, Color.GREEN), new Circle(50, Color.YELLOW), new Circle(50, Color.RED));
    root.addRow(1, new Rectangle(50, 50), new Rectangle(50, 50), new Rectangle(50, 50));

    Board board = new Board(root);

    EventHandler<MouseEvent>[] handlers = new EventHandler[] {
        board.new CircleEventHandler(),
        board.new RectangleEventHandler()
    };

    for (Node n : root.getChildren()) {
        n.setOnMouseClicked(handlers[GridPane.getRowIndex(n)]);
    }

    Scene scene = new Scene(root);

    primaryStage.setScene(scene);
    primaryStage.show();
}

至于在您的代码中查找 NPE 的来源：没有更多信息这是不可能的，因为没有关于为什么 gp 为空的信息。

在 JavaFX 中让棋子转到您想要的磁贴？

Having a checker piece go to the tile you want it to in JavaFX?

java

events

javafx

handler

eventhandler