在国际象棋游戏的 Gridpane 中交换节点

Question

我无法单击一个按钮，然后单击另一个按钮与之前单击的按钮交换。然后将第一个点击的按钮设为空白按钮。

我想不出该怎么做。我只是尝试使用 if 语句，例如

If button = this{                 //this should find the first button
    if button = that{             //this should find the second button
       that = this                //this swaps the buttons
    }
   this = blank                  //and ends with making the first button 
blank
}

这不起作用，因为它直接通过了第二个 if 语句，并使第一个按钮空白而不交换任何内容。

不需要太多代码，这只是测试代码来找出这个单一的动作

public class SimpleButtonSwapper extends Application {

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

    @Override
    public void start(Stage stage) {

        GridPane pane = new GridPane();
        pane.setPadding(new Insets(50, 50, 50, 50));           //creates 50 pixel padding
        pane.setVgap(2);
        pane.setHgap(2);

        Scene scene = new Scene(pane);

        Canvas canvas = new Canvas(50, 400);
        GraphicsContext graphics = canvas.getGraphicsContext2D();
        pane.getChildren().add(canvas);

        stage.setTitle("Chess");

        Button[] buttons = new Button[6];

        for (int i = 0; i < 6; i++) {
            buttons[i] = new Button();
            buttons[i].setText("banana " + i);
        }

        for (int i = 0; i < 6; i++) {
            pane.add(buttons[i], i, 0);
        }

        for (int i = 0; i < 6; i++) {

            buttons[i].setOnAction(new EventHandler<ActionEvent>() {

                @Override
                public void handle(ActionEvent event) {

                }
            });
        }

        stage.setScene(scene);

        stage.show();
    }
}

Answer 1

以下是mre 在GridPane 中交换两个按钮：

import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.Pane;
import javafx.scene.layout.VBox;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class FxMain extends Application {

    private static final int COLS = 5, ROWS = 5;
    private int clickCounter = 0;
    private GridPane grid;
    private Button first, second;

    @Override
    public void start(Stage primaryStage){

        VBox root = new VBox(10);
        root.setPadding(new Insets(10));
        root.getChildren().addAll(makeGrid(), new Text("Click 2 buttons to swap them"));
        primaryStage.setScene(new Scene(root));
        primaryStage.sizeToScene();
        primaryStage.show();
    }

    private Pane makeGrid() {

        grid = new GridPane();
        for(int rowIndex = 0; rowIndex < ROWS ; rowIndex++) {
            //an array to hold buttons of one row 
            Node[] nodes = new Node[COLS];
            for(int colIndex = 0; colIndex < COLS ; colIndex++) {
                Button node= new Button(rowIndex+""+colIndex);
                node.setOnAction(e->buttonCliked(e.getSource())); //add action listener 
                node.prefHeight(100); node.prefWidth(100);
                nodes[colIndex]= node;
            }
            grid.addRow(rowIndex, nodes);
        }
        return grid;
    }

    private void buttonCliked(Object source) {

        if(!(source instanceof Button)) return;
        Button button  = (Button)source;

        if(clickCounter == 0){
            first = button;
        }else{
            second = button;
            swap();
        }

        System.out.println(clickCounter + " " + ((Button)source).getText()    );
        clickCounter=  ++clickCounter %2 ;  // changes values between 0 1
    }

    private void swap() {
        int firstRow = GridPane.getRowIndex(first);
        int firstCol = GridPane.getColumnIndex(first);
        int secondRow = GridPane.getRowIndex(second);
        int secondCol = GridPane.getColumnIndex(second);
        grid.getChildren().removeAll(first, second);
        grid.add(first, secondCol, secondRow);
        grid.add(second, firstCol, firstRow);
    }

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

---

Answer 2

您可以创建一个属性来保存选定的按钮状态....但我认为“更改文本”并不能真正帮助您创建国际象棋游戏。我会有一个“ChessPiece”对象及其基础规则/属性...

 SimpleObjectProperty<Button> selectedButtonProperty = new SimpleObjectProperty<>();

 for (int i = 0; i < 6; i++)
 {

     buttons[i].setOnAction(new EventHandler<ActionEvent>()
     {
         @Override
         public void handle(ActionEvent event)
         {
             Button thisButton = (Button) event.getSource();
             if (selectedButtonProperty.get() == null)
             {
                selectedButtonProperty.set(thisButton);
             } else
             {
                 thisButton.setText(selectedButtonProperty.get().getText());
                 selectedButtonProperty.get().setText(null);
                 selectedButtonProperty.set(null);
             }

         }
     });

  }

Answer 3

我真的不知道这在国际象棋游戏中有何用处，但这是我在 gridPane 中交换两个按钮所做的操作

我为第一次单击的按钮创建了一个变量，该变量在您单击按钮之前将保持为“null”，因此第一次单击会将单击的按钮保存在“第一次”中，第二次单击将交换并删除内容'第一'

要交换它们，我必须检索它们在 gridPane 中的位置（我只保存了列索引，您可能还需要保存行索引）

//looping through the buttons
for (Button button : buttons) {
    //adding a listener
    button.setOnAction(e -> {
        if (first == null)
            first = button;
        else {
            if (first != button) {
                Button second = button;
                int index1 = GridPane.getColumnIndex(first);
                int index2 = GridPane.getColumnIndex(second);
                pane.getChildren().removeAll(first, second);
                pane.add(first, index2, 0);
                pane.add(second, index1, 0);
            }
            first = null;
        }
    });
}