关于 GridLayout 和 paintComponent 方法的 Java Swing 问题

Question

在这个程序中，我们需要创建一个 8x8 的“LifeCell”小部件网格。讲师没有提到小部件必须是 Shape 的对象，所以我继续使用 GridLayout 类。 GridLayout 类工作正常(据我所知，因为没有视觉辅助来确认。)该程序的目的是玩生命游戏，用户可以点击其中一个LifeCell 小部件并在“活着”或“死亡”状态之间切换。

我的问题在很大程度上取决于如何绘制要绘制的单元格。这可能是我的代码有问题，但我不是 100% 确定。

程序2.java

public class Program2 extends JPanel implements ActionListener {
private LifeCell[][] board; // Board of life cells.
private JButton next; // Press for next generation.
private JFrame frame; // The program frame.

public Program2() {
    // The usual boilerplate constructor that pastes the main
    // panel into a frame and displays the frame. It should
    // invoke the "init" method before packing the frame
    frame = new JFrame("LIFECELL!");
    frame.setContentPane(this);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    this.init();
    frame.pack();
    frame.setVisible(true);
}
    public void init() {
    // Create the user interface on the main panel. Construct
    // the LifeCell widgets, add them to the panel, and store
    // them in the two-dimensional array "board". Create the
    // "next" button that will show the next generation.
    LifeCell[][] board = new LifeCell[8][8];
    this.setPreferredSize(new Dimension(600, 600));
    this.setBackground(Color.white);
    this.setLayout(new GridLayout(8, 8));
    // here is where I initialize the LifeCell widgets
    for (int u = 0; u < 8; u++) {
        for (int r = 0; r < 8; r++) {
            board[u][r] = new LifeCell(board, u, r);
            this.add(board[u][r]);
            this.setVisible(true);

        }
    }

生命细胞.java

 public class LifeCell extends JPanel implements MouseListener {
   private LifeCell[][] board; // A reference to the board array.
   private boolean alive;      // Stores the state of the cell.
   private int row, col;       // Position of the cell on the board.
   private int count;          // Stores number of living neighbors.

   public LifeCell(LifeCell[][] b, int r, int c) {
       // Initialize the life cell as dead.  Store the reference
       // to the board array and the board position passed as
       // arguments.  Initialize the neighbor count to zero.
       // Register the cell as listener to its own mouse events.
       this.board = b;
       this.row = r;
       this.col = c;
       this.alive = false;
       this.count = 0;
       addMouseListener(this);
   }   

这是 paintComponent 方法:

   public void paintComponent(Graphics gr) {
       // Paint the cell.  The cell must be painted differently
       // when alive than when dead, so the user can clearly see
       // the state of the cell.
           Graphics2D g = (Graphics2D) gr;
           super.paintComponent(gr);
           g.setPaint(Color.BLUE);
   }

我不需要确切的解决方案来修复它，但我无能为力地试图让它工作。

谢谢。

编辑:

我添加了更多的 Program2.java 类片段，明天我可以回来查看我要去 sleep 了，我感谢所有帮助的人。

编辑#2:

当我用 8x8 GridLayout 填充我的框架时，我真正感到困惑的是，由于缺少更好的词，每个单独的“单元格”都是 LifeCell 类型。如何为每个 LifeCell 涂上不同的颜色？如果这对你们有任何意义，我可以尝试尽可能多地修改它。还有 camickr，我会看看那个网站，谢谢。

可以找到赋值here以避免对我的问题和/或代码片段产生任何混淆。

Answer 1

JPanel 没有默认的首选大小或可见内容。您需要添加某种可见组件(例如 JLabel)或为其指定首选大小。

除此之外，如果您按如下方式设置，您的布局应该可以正常工作:

JFrame frame = new JFrame();
Container cp = frame.getContentPane();
cp.setLayout(new GridLayout(8, 8));
for (int i = 0; i < 8; i++)
    for (int j = 0; j < 8; j++)
        cp.add(new JLabel(i + "-" + j));
frame.pack();
frame.setVisible(true);