Java - 为什么 mouseClicked 方法在执行完成后不会永久重置变量？

Question

我有一个单元格对象的二维数组，其中包含其“tileCode”的字符串变量，当我使用键盘设置 Activity 图 block 代码，然后单击二维数组中所需的单元格时，它应该更改该单元格的tileCode到当前 Activity 图 block 。但是，当我单击该图 block 后，它立即切换回之前的图 block 代码和图像。

默认情况下，每个图 block 都设置为一个地板。

public static JFrame frame = new JFrame("Tool");
public static Panel panel;

public Image wall, floor;

public int rows = 50;
public int cols = 50;
public int xCoor = 20;
public int yCoor = 20;

String activeKey = "f";
Image activeImage = floor;

//Arrays
Rectangle[][] recs = new Rectangle[rows][cols];
Cell[][] cells = new Cell[rows][cols];
public Set <Integer> keysDown = new HashSet<>();

public LevelDesignTool() {
    loadImages();
    panel = new Panel();
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.setSize(1400, 1100);
    frame.setFocusable(true);
    frame.requestFocus();
    frame.setVisible(true);
    frame.getContentPane().add(panel);

    KeyboardFocusManager manager = KeyboardFocusManager.getCurrentKeyboardFocusManager();
    manager.addKeyEventDispatcher(this);
    addMouseListener(this);

    myThread thread = new myThread();
    thread.start();
}

class Panel extends JPanel {

    public void paintComponent(Graphics g) {

        Graphics2D g2D = (Graphics2D)g;

        //Loading array of Tile Types
        ArrayList<String> TileTypes = new ArrayList<>();
        try {
            Scanner TileFileScanner = new Scanner(new File("TileTypes"));

            while(TileFileScanner.hasNext()) {
                TileTypes.add(TileFileScanner.nextLine());
            }

        }
        catch(FileNotFoundException e) {
            System.err.println("Tile Type file not found.");
        }


        g.setFont(new Font("Italic",Font.PLAIN, 25));
        g.drawString("Press Enter to save to file.", 1050, 50);

        //Tile Type key on the rigt side of the screen
        int y = 550;
        for(int i = 0; i < TileTypes.size(); i++) {
            g.drawString(TileTypes.get(i), 1050, y);
            y += 30;
        }

        //Creating 2D array of Rectangles
        xCoor = 20;
        for(int r = 0; r < rows; r++) {
            yCoor = 20;
            for(int c = 0; c < cols; c++) {
                recs[r][c] = new Rectangle(xCoor, yCoor, 18, 18);
                yCoor += 19;
            }
            xCoor += 19;
        }
        //Creating 2D array of cells
        for(int r = 0; r < rows; r++) {

            for(int c = 0; c < cols; c++) {

                cells[r][c] = new Cell(recs[r][c], "f", activeImage);
                xCoor += 21;
            }
            xCoor = 0;
            yCoor += 21;
        }
        //Drawing cells
        for(int r = 0; r < rows; r++) {

            for(int c = 0; c < cols; c++) {

                g.fillRect((int)cells[r][c].r.getX(), (int)cells[r][c].r.getY(), (int)cells[r][c].r.getWidth(), (int)cells[r][c].r.getHeight());
                g.setColor(Color.BLACK);
            }
        }
        //Drawing the images stored in each cell object
        for(int r = 0; r < rows; r++) {

            for(int c = 0; c < cols; c++) {

                cells[r][c].image = floor;
                g.drawImage(cells[r][c].getImage(), cells[r][c].getX(), cells[r][c].getY(), this);
            }
        }


        addMouseListener(new MouseAdapter() { 

            @Override
            public void mouseReleased(MouseEvent e) {

                for(int r = 0; r < rows; r++) {

                    for(int c = 0; c < cols; c++) {

                        if (cells[r][c].getRect().contains(e.getX(), e.getY())) {
                            cells[r][c].tileCode = activeKey;
                            cells[r][c].image = activeImage;
                            //System.out.println("click registered");
                        }
                    }
                }
            }
        }); 
    }
}

//Must have these implemeted because they are from an interface
@Override
public void mouseClicked(MouseEvent e) {}
@Override
public void mouseEntered(MouseEvent e) {}
@Override
public void mouseExited(MouseEvent e) {}
@Override
public void mousePressed(MouseEvent e) {}
@Override
public void mouseReleased(MouseEvent e) {}


public void update() throws Exception {

    //System.out.println(cells[0][0].getTileCode());
    //System.out.println(activeKey);
}

@Override
public boolean dispatchKeyEvent(KeyEvent event) {

    if(event.getID() == KeyEvent.KEY_PRESSED){
        keysDown.add(event.getKeyCode());
        if(event.getKeyCode() == KeyEvent.VK_F) {
            activeKey = "f";
            activeImage = floor;
        }
        if(event.getKeyCode() == KeyEvent.VK_E) {
            activeKey = "e";
        }
        if(event.getKeyCode() == KeyEvent.VK_W) {
            activeKey = "w";
            activeImage = wall;
        }
    }
    if(event.getID() == KeyEvent.KEY_RELEASED) 
        keysDown.remove(event.getKeyCode());

    return false;
}

class myThread extends Thread {
    public void run() {
        while(true) {
            try {
                Thread.sleep(15);
                frame.repaint();
                update();   //update any game state changes for the next frame
            }
            catch(Exception e) {
                System.out.println(e);
            }
        }
    }
}

private void loadImages() {
    floor = new ImageIcon("images/Floor.png").getImage();
    wall = new ImageIcon("images/Wall.png").getImage();
}

//Runs code
public static void main(String[] args) {
    new LevelDesignTool();
}

}

单击某个单元格后，其图像应更改为 Activity 图像，并且图 block 代码应更改为 Activity 图 block 代码。

Answer 1

问题是您在每次调用paintComponent时都初始化数据(并添加新的mouseListener)。每次重新绘制时，都会将所有数据重置为“floor”，这会覆盖您在鼠标监听器中所做的任何更改。另外，请注意，在“绘制单元格”循环中，您在绘制图像之前将图像重置为地板 (cells[r][c].image = Floor;)。这将再次重置您在鼠标监听器中设置的数据。

解决方案是将 mouseListener 和初始化代码移至 Panel 的构造函数中，如下所示:

class Panel extends JPanel {
    ArrayList<String> TileTypes = new ArrayList<String>();
    public Panel() {
        //Loading array of Tile Types
        try {
            Scanner TileFileScanner = new Scanner(new File("TileTypes"));
            while(TileFileScanner.hasNext()) {
                TileTypes.add(TileFileScanner.nextLine());
            }
        } catch(FileNotFoundException e) {
            System.err.println("Tile Type file not found.");
        }

        //Creating 2D array of Rectangles
        xCoor = 20;
        for(int r = 0; r < rows; r++) {
            yCoor = 20;
            for(int c = 0; c < cols; c++) {
                recs[r][c] = new Rectangle(xCoor, yCoor, 18, 18);
                yCoor += 19;
            }
            xCoor += 19;
        }

        //Creating 2D array of cells
        for(int r = 0; r < rows; r++) {
            for(int c = 0; c < cols; c++) {
                cells[r][c] = new Cell(recs[r][c], "f", activeImage);
                cells[r][c].image = floor;
                xCoor += 21;
            }
            xCoor = 0;
            yCoor += 21;
        }

        addMouseListener(new MouseAdapter() { 
            @Override
            public void mouseReleased(MouseEvent e) {
                for(int r = 0; r < rows; r++) {
                    for(int c = 0; c < cols; c++) {
                        if (cells[r][c].getRect().contains(e.getX(), e.getY())) {
                            cells[r][c].tileCode = activeKey;
                            cells[r][c].image = activeImage;
                            //System.out.println("click registered");
                        }
                    }
                }
            }
        }); 
    }

    public void paintComponent(Graphics g) {
        Graphics2D g2D = (Graphics2D)g;
        g.setFont(new Font("Italic",Font.PLAIN, 25));
        g.drawString("Press Enter to save to file.", 1050, 50);

        //Tile Type key on the rigt side of the screen
        int y = 550;
        for(int i = 0; i < TileTypes.size(); i++) {
            g.drawString(TileTypes.get(i), 1050, y);
            y += 30;
        }

        //Drawing cells
        for(int r = 0; r < rows; r++) {
            for(int c = 0; c < cols; c++) {
                g.fillRect((int)cells[r][c].r.getX(), (int)cells[r][c].r.getY(),
                           (int)cells[r][c].r.getWidth(), (int)cells[r][c].r.getHeight());
                g.setColor(Color.BLACK);
            }
        }
        //Drawing the images stored in each cell object
        for(int r = 0; r < rows; r++) {
            for(int c = 0; c < cols; c++) {
                g.drawImage(cells[r][c].getImage(), cells[r][c].getX(), cells[r][c].getY(), this);
            }
        }
    }
}

另外，这不是您问题的一部分，但您正在丢弃线程中的中断异常。改为这样做:

public void run() {
    while (!Thread.interrupted()) {
        try {
            Thread.sleep(15);
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }
}