我不清楚如何在现有代码中重新绘制 JPanel。我也不明白paintComponent 是如何被调用的。首先，我只想清除 JPanel，但我什至不能这样做。
我希望能够按下“下一步移动”按钮并重新绘制 JPanel，因为我正在从中读取颜色的网格发生变化。我无法通过调用 revalidate()、removeAll() 和 repaint() 将 JPanel 更改为我的图块 JPanel。
我称这些为俄罗斯方块网格（图块）下方的现有JPanel（如图）没有任何反应。
在下面的代码中，我有一个扩展 JPanel 的嵌套类，并且 setup 函数创建了一个采用 2d arraylist 网格并构造原始网格的窗口。
我如何至少清除 JPanel 甚至更好地用新网格重绘......我在想一种方法：
public void redraw(Grid g) {
removeAll();
getColor(); //gets new grid of tiles
repaint();
revalidate();
}
在嵌套的 JPanel 类中，但这似乎根本没有改变 JPanel，甚至没有清除当前的绘图。
public class BoardGraphics {
public ArrayList<ArrayList<Color>> colours;
private final int width;
private int height;
private JFrame display;
private TetrisSquares tiles;
private Container c;
public BoardGraphics(int width, int height,
ArrayList<ArrayList<Integer>> grid) {
this.width = width;
this.height = height;
colours = new ArrayList<ArrayList<Color>>(width);
setColor(grid);
setup();
}
public void setup() {
System.out.println("Let the Tetris Begin");
display = new JFrame("Tetris Agent");
final TextArea welcome = new TextArea("Welcome to Tetris", 2, 10,
TextArea.SCROLLBARS_NONE);
welcome.setBackground(Color.black);
welcome.setForeground(Color.red);
welcome.setFont(new Font("monospaced", 0, 11));
welcome.setEditable(false);
Button btnStart = new Button("Next Move");
btnStart.setFocusable(false);
tiles = new TetrisSquares(TetrisBoard.BOARD_WIDTH, height);
c = new Container();
c.setLayout(new BorderLayout());
c.add(welcome, BorderLayout.NORTH);
c.add(tiles);
c.add(btnStart,BorderLayout.SOUTH);
btnStart.addActionListener(new ActionListener()
{
public void actionPerformed(ActionEvent e)
{
tiles.removeAll();
tiles.revalidate();
}
});
final Container main = new Container();
main.setLayout(new GridLayout(1, 2));
display.add(c);
display.pack();
display.addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
display.setVisible(true);
}
public ArrayList<ArrayList<Color>> getBoard() {
return colours;
}
public void setColor(ArrayList<ArrayList<Integer>> grid) {
ListIterator<Integer> li;
for (int i = 0; i < width; i++) {
colours.add(new ArrayList<Color>());
li = grid.get(i).listIterator();
for (int j = 0; j <= height; j++) {
int n = 0;
if(li.hasNext()) {
n = li.next();
}
switch (n) {
case 1:
colours.get(i).add(Color.red);
break;
case 2:
colours.get(i).add(Color.pink);
break;
case 3:
colours.get(i).add(Color.orange);
break;
case 4:
colours.get(i).add(Color.yellow);
break;
case 5:
colours.get(i).add(Color.green);
break;
case 6:
colours.get(i).add(Color.cyan);
break;
case 7:
colours.get(i).add(Color.blue);
break;
default:
colours.get(i).add(Color.gray);
break;
}
}
}
}
public class TetrisSquares extends JPanel {
public int width;
public int height;
public TetrisSquares(int width, int height) {
this.width = width;
this.height = width;
this.setPreferredSize(new Dimension(width * 20, height * 20));
}
public void redraw() {
removeAll();
//add your elements
//revalidate();
//repaint();
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D graphics = (Graphics2D) g;
graphics.setColor(Color.BLACK);
/*
* tiles.width = getSize().width / width; tiles.height =
* getSize().height / 800;
*
* insets.left = (getSize().width - width * tiles.width) / 2;
* insets.right = insets.left; insets.top = 0; insets.bottom =
* getSize().height - height * tiles.height;
*/
Dimension size = getSize();
Insets insets = getInsets();
int w = size.width - insets.left - insets.right;
int h = size.height - insets.top - insets.bottom;
int tileWidth = w / width;
int tileHeight = w / width;
ListIterator<Color> li;
for (int i = 0; i < width; i++) {
li = colours.get(i).listIterator();
int n = 20;
while(li.hasNext()) {
--n;
int x = (int) (i * tileWidth);
int y = (int) (n * tileHeight);
graphics.setColor(li.next());
graphics.fillRect(x, y, tileWidth, tileHeight);
graphics.setColor(Color.black);
graphics.drawRect(x, y, tileWidth, tileHeight);
}
}
}
}
}