java - SequentialTransition 重复次数超过循环次数

Question

我可能会写出故障，但我知道我即将被带到学校学习 Javafx 的一个我不知道存在的功能。

当我使用 PauseTransition 和 SequentialTransition 的组合来制作由按钮网格组成的连接四个游戏时，按钮一个按钮地向下 float 。在一个非常具体的用例下，我得到了一个非常意想不到的结果。

这里是运行和复制错误所需的所有代码，已编辑为独立且简约，同时仍保留基本的游戏逻辑。

import javafx.animation.PauseTransition;
import javafx.animation.SequentialTransition;
import javafx.application.Application;
import javafx.event.Event;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.GridPane;
import javafx.stage.Stage;
import javafx.util.Duration;

public class ConnectFourApplication extends Application {
    public static final int NUM_COLUMNS = 8;
    public static final int NUM_ROWS = 8;
    private Button[][] buttons;
    private int row =0;
    private int column = 0;
    private PauseTransition buttonGravityPause;
    private Scene scene;
    private BorderPane border;
    private ConnectEnum turnColor=ConnectEnum.RED;

    public enum ConnectEnum{
        RED ("Red"), BLACK ("Black");
        private String turn;
        ConnectEnum( String value) {
            this.turn = value;
        }
    }

    @Override
    public void start(Stage primaryStage) {
        buttons = new Button[NUM_ROWS][NUM_COLUMNS];
        GridPane gridpane = new GridPane();
        Button turn = new Button("Take turn");
        for(int i=0; i<NUM_ROWS; i++){
            for(int j = 0; j<NUM_COLUMNS; j++){
                buttons[i][j] = new Button("Empty");
                buttons[i][j].setMinHeight(20);
                buttons[i][j].setMaxWidth(Double.MAX_VALUE);
                buttons[i][j].setOnAction(new ButtonHandler<>(i,j));
                gridpane.add(buttons[i][j], j, (NUM_ROWS-1)-i);
            }
        }

        buttonGravityPause = new PauseTransition(new Duration(700));
        buttonGravityPause.setOnFinished(event-> {
            if (this.row>0) {
                buttons[this.row - 1][this.column].setStyle("-fx-background-color:blue");
                buttons[this.row][this.column].setStyle("");
                this.row = this.row - 1;
            }else System.out.println("THis should never happen, row is: "+this.row);
        });

        SequentialTransition s = new SequentialTransition(buttonGravityPause);
        s.setOnFinished(floatDown-> {
            System.out.println("The button " +row+ " " +column+" has been chosen");
            buttons[this.row][this.column].setText(""+getTurn());
            buttons[this.row][this.column].setStyle("-fx-background-color:"+getTurn());
            changeTurn();
        });

        turn.setOnAction(e->{
            System.out.println("The button " +row+ " " +column+" has been chosen");
            int i =0;
            while(this.row-i>0 && buttons[this.row-(i+1)][this.column].getText().equals("Empty"))i++;
            s.setCycleCount(i);
            System.out.println("i is: "+i+"  but cycle count is: "+s.getCycleCount());
            if(i>0)s.play(); else{
                System.out.println("The button " +row+ " " +column+" has been chosen");
                buttons[this.row][this.column].setText(""+getTurn());
                buttons[this.row][this.column].setStyle("-fx-background-color:"+getTurn());
                changeTurn();
            }
        });

        border = new BorderPane();
        border.setCenter(gridpane);
        border.setBottom(turn);
        scene = new Scene(border, 510, 380);

        primaryStage.setTitle("Connect Four");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
    private ConnectEnum getTurn(){return this.turnColor;}
    private void changeTurn(){this.turnColor = this.turnColor==ConnectEnum.RED? ConnectEnum.BLACK:ConnectEnum.RED;}
    private void setRowColumn(int row, int column){
        this.row=row;
        this.column=column;
    }
    private int getRow(){
        return this.row;
    }
    private int getColumn(){
        return this.column;
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

    class ButtonHandler<T extends Event> implements EventHandler<T> {
        private int row;
        private int col;

        ButtonHandler(int row, int column){
            this.row=row;
            this.col=column;
        }

        @Override
        public void handle(T event){
            if (buttons[getRow()][getColumn()].getText().equals("Empty")) buttons[getRow()][getColumn()].setStyle("");
            if (buttons[this.row][this.col].getText().equals("Empty")) {
                setRowColumn(this.row, this.col);
                buttons[row][col].setStyle("-fx-background-color:blue");
            }else System.out.println("This space is occupied");
        }
    }
}

除了我的情况外，它在所有情况下都能正确运行 1. 选择一个紧邻已放置按钮上方的按钮，然后 2. 下一个选择，如果将其放置在几个空白点上方，将导致以下控制台输出(包括前几个表现良好和预期的语句):

The button2 1has been choseni is: 2  but cycle count is: 2The button 0 1 has been chosenfalseThe button1 1has been choseni is: 0  but cycle count is: 0falseThe button4 2has been choseni is: 4  but cycle count is: 4THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0THis should never happen, row is: 0......The button 0 2 has been chosen

重现错误/竞争条件:1. 选择任意按钮，按轮流。2. 选择紧邻当前彩色按钮顶部的按钮，然后按“轮流”。3. 选择一个不在底行按钮中的按钮，然后观看奇迹发生。

以前这会导致数组越界，但我添加了一个 if 语句，这样我就可以避免错误并尝试阐明正在发生的情况。

如果有人对 JavaFX 这方面有任何经验，我将非常感激，因为我不知所措。

Answer 1

使 SequentialTransition 成为一个字段，并在单击 turn 时构造一个新字段(而不是重用同一实例)，解决了问题:

    turn.setOnAction(e->{
        int i = 0;
        while(row-i>0 && buttons[row-(i+1)][column].getText().equals("Empty")) {
            i++;
        }

        if(i>0) {
            s = new SequentialTransition(buttonGravityPause);
            s.setAutoReverse(false);
            s.setOnFinished(floatDown-> {
                buttons[row][column].setText(""+getTurn());
                buttons[row][column].setStyle("-fx-background-color:"+getTurn());
                changeTurn();
            });
            s.setCycleCount(i);
            s.play();
        } else{
            buttons[row][column].setText(""+getTurn());
            buttons[row][column].setStyle("-fx-background-color:"+getTurn());
            changeTurn();
        }
    });

我不确定为什么重用 SequentialTransition 实例会导致问题。
希望有了解的 friend 可以补充一下。
可以从here复制工作演示代码