Question

我正在尝试仅使用Board类作为GUI，使用Game类来运行和测试游戏规则，将Pieces作为每个棋子的父类，使用Player类来指示谁来使用Java制作象棋游戏。我首先用8 x 8 = 64个按钮填充电路板。为了实现每个部件的有效运动，我需要获取每个按钮的地址或索引。最初我没有使用2d数组，但我认为将按钮放入2d数组并获取它们的索引来控制棋子的移动会更容易。到目前为止，这是我尝试过的操作，但我不知道为什么会出现NullPointer错误。

我会寻求任何帮助或建议。

import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;

public class Board extends Application {
    GridPane board = new GridPane();
    Scene s = new Scene(board);
    Button buttonArray[][];
    private void showBoard() {
        for (int i = 0; i < 8; i++) {
            for (int j = 0; j < 8; j++) {
                buttonArray[i][j] = new Button();


                buttonArray[i][j].setMinSize(70, 70);



                if ((i + j) % 2 == 0) { 
                    buttonArray[i][j].setStyle("-fx-background-color: #0e0f0f");
                } else {
                    buttonArray[i][j].setStyle("-fx-background-color: #ededed");
                }
                buttonArray[i][j].setOnAction(this::onSelect);

                board.add(buttonArray[i][j], i, j);
            }
        }
    }


    // event listener
    private void onSelect(ActionEvent event) {
        Button b = (Button) event.getSource();
        System.out.println("get source" + b);
        b.setStyle("-fx-background-color: magenta");

    }

    @Override
    public void start(Stage stage) throws Exception {
        showBoard();
        stage.setScene(s);
        stage.show();
    }

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

}

//错误stackTrace

Exception in Application start method
java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
    at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at sun.launcher.LauncherHelper$FXHelper.main(Unknown Source)
Caused by: java.lang.RuntimeException: Exception in Application start method
    at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$154(LauncherImpl.java:182)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
    at Board.showBoard(Board.java:15)
    at Board.start(Board.java:45)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$161(LauncherImpl.java:863)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$174(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$172(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$173(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.lambda$null$147(WinApplication.java:177)
    ... 1 more
Exception running application Board

JavaFx如何使用2d数组向GridPane添加按钮？

0 个答案: